Programs & Examples On #Rule

Rule might refer to various things: business rules, JUnit rules, a rule of thumb, rules engines, rules in Makefiles ...

Getting all files in directory with ajax

Javascript which runs on the client machine can't access the local disk file system due to security restrictions.

If you want to access the client's disk file system then look into an embedded client application which you serve up from your webpage, like an Applet, Silverlight or something like that. If you like to access the server's disk file system, then look for the solution in the server side corner using a server side programming language like Java, PHP, etc, whatever your webserver is currently using/supporting.

Invalid hook call. Hooks can only be called inside of the body of a function component

If all the above doesn't work, especially if having big size dependency (like my case), both building and loading were taking a minimum of 15 seconds, so it seems the delay gave a false message "Invalid hook call." So what you can do is give some time to ensure the build is completed before testing.

How to style components using makeStyles and still have lifecycle methods in Material UI?

Hi instead of using hook API, you should use Higher-order component API as mentioned here

I'll modify the example in the documentation to suit your need for class component

import React from 'react';
import PropTypes from 'prop-types';
import { withStyles } from '@material-ui/styles';
import Button from '@material-ui/core/Button';

const styles = theme => ({
  root: {
    background: 'linear-gradient(45deg, #FE6B8B 30%, #FF8E53 90%)',
    border: 0,
    borderRadius: 3,
    boxShadow: '0 3px 5px 2px rgba(255, 105, 135, .3)',
    color: 'white',
    height: 48,
    padding: '0 30px',

class HigherOrderComponentUsageExample extends React.Component {
    const { classes } = this.props;
    return (
      <Button className={classes.root}>This component is passed to an HOC</Button>

HigherOrderComponentUsageExample.propTypes = {
  classes: PropTypes.object.isRequired,

export default withStyles(styles)(HigherOrderComponentUsageExample);

React Hook "useState" is called in function "app" which is neither a React function component or a custom React Hook function

React components (both functional as well as class) must begin with a capital letter. Like

const App=(props)=><div>Hey</div>

class App extends React.Component{
     return <div>Hey</div>

React identifies user-defined components by following this semantic. React's JSX transpiles to React.createElement function which returns an object representation of the dom node. The type property of this object tells whether it is a user-defined component or a dom element like div. Therefore it is important to follow this semantics

Since useState hook can only be used inside the functional component(or a custom hook) this is the reason why you are getting the error because react is not able to identify it as a user-defined component in the first place.

useState can also be used inside the custom hooks which is used for the reusability and the abstraction of logic. So according to the rules of hooks, the name of a custom hook must begin with a "use" prefix and must be in a camelCase

Can't perform a React state update on an unmounted component

The solution from @ford04 didn't worked to me and specially if you need to use the isMounted in multiple places (multiple useEffect for instance), it's recommended to useRef, as bellow:

  1. Essential packages
  "react": "17.0.1",
"devDependencies": { 
  "typescript": "4.1.5",

  1. My Hook Component
export const SubscriptionsView: React.FC = () => {
  const [data, setData] = useState<Subscription[]>();
  const isMounted = React.useRef(true);

  React.useEffect(() => {
    if (isMounted.current) {
      // fetch data
      // setData (fetch result)

      return () => {
        isMounted.current = false;

Why do I keep getting Delete 'cr' [prettier/prettier]?

I know this is old but I just encountered the issue in my team (some mac, some linux, some windows , all vscode).

solution was to set the line ending in vscode's settings:


    "files.eol": "\n",

How to compare oldValues and newValues on React Hooks useEffect?

Incase anybody is looking for a TypeScript version of usePrevious:

In a .tsx module:

import { useEffect, useRef } from "react";

const usePrevious = <T extends unknown>(value: T): T | undefined => {
  const ref = useRef<T>();
  useEffect(() => {
    ref.current = value;
  return ref.current;

Or in a .ts module:

import { useEffect, useRef } from "react";

const usePrevious = <T>(value: T): T | undefined => {
  const ref = useRef<T>();
  useEffect(() => {
    ref.current = value;
  return ref.current;

WARNING: API 'variant.getJavaCompile()' is obsolete and has been replaced with 'variant.getJavaCompileProvider()'

Updating gradle to gradle:3.3.0

The default 'assemble' task only applies to normal variants. Add test variants as well.

android.testVariants.all { variant ->
    tasks.getByName('assemble').dependsOn variant.getAssembleProvider()

also comment apply fabric

//apply plugin: 'io.fabric'

Handling back button in Android Navigation Component

My Opinion requireActivity().onBackPressed()


Android design support library for API 28 (P) not working

if you want to solve this problem without migrating to AndroidX (I don't recommend it)

this manifest merger issue is related to one of your dependency using androidX.

you need to decrease this dependency's release version. for my case :

I was using google or firebase

api ''

I have to decrease it 15.0.1 to use in support library.

Failed to resolve:

From the docs:-

Your app gradle file now has to explicitly list as a dependency for Firebase services to work as expected.


 implementation ''

and in top level gradle file use the latest version of google play services:

classpath ''


You need to add the google() repo in the top level gradle file, as specified in the firebase docs and also it should be before jcenter():

 buildscript {
  repositories {

dependencies {
  classpath ''
  classpath ''

allprojects {
     repositories {

task clean(type: Delete) {
  delete rootProject.buildDir

Could not find module "@angular-devkit/build-angular"

Just update the angular version and add the below dependency:

ng update

npm update

npm i @angular-devkit/build-angular

Error : Program type already present:$Behavior

I know it's a late answer but I had the same problem and my solution was just adding implementation ' or any above support design libraries !!

VSCode single to double quote automatic replace

Install prettier extension and paste below code in your VSCode settings.json file

 "prettier.useEditorConfig": false,
 "prettier.singleQuote": true

this will ignore your .editorconfig file setting.

Error:Cannot fit requested classes in a single dex file.Try supplying a main-dex list. # methods: 72477 > 65536

In build:app

apply plugin: ''
android {
compileSdkVersion 28
defaultConfig {
    applicationId "com.proyecto.marketdillo"
    minSdkVersion 14
    targetSdkVersion 28
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner ""
    multiDexEnabled true
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), ''
dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation ''
implementation ''
implementation ''
implementation ''
implementation ''
implementation ''
implementation 'com.squareup.picasso:picasso:2.5.2'
testImplementation 'junit:junit:4.12'
androidTestImplementation ''
androidTestImplementation ''
implementation ''
implementation ''
apply plugin: ''

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

I found the solution as Its problem with Android Studio 3.1 Canary 6

My backup of Android Studio 3.1 Canary 5 is useful to me and saved my half day.

Now My build.gradle:

apply plugin: ''

android {
    compileSdkVersion 27
    buildToolsVersion '27.0.2'
    defaultConfig {
        applicationId "com.example.demo"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner ""
        vectorDrawables.useSupportLibrary = true
    dataBinding {
        enabled true
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), ''
    productFlavors {

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation "${rootProject.ext.supportLibVersion}"
    implementation "${rootProject.ext.supportLibVersion}"
    implementation "${rootProject.ext.supportLibVersion}"
    implementation "${rootProject.ext.supportLibVersion}"
    implementation "${rootProject.ext.supportLibVersion}"
    implementation "com.squareup.retrofit2:retrofit:2.3.0"
    implementation ""
    implementation ""
    implementation "com.squareup.retrofit2:converter-gson:2.3.0"
    implementation "com.squareup.okhttp3:logging-interceptor:3.6.0"
    implementation "com.squareup.picasso:picasso:2.5.2"
    implementation "com.dlazaro66.qrcodereaderview:qrcodereaderview:2.0.3"
    compile 'com.github.elevenetc:badgeview:v1.0.0'
    annotationProcessor 'com.github.elevenetc:badgeview:v1.0.0'
    testImplementation "junit:junit:4.12"
    androidTestImplementation("", {
        exclude group: "", module: "support-annotations"

and My gradle is:

classpath ''

and its working finally.

I think there problem in Android Studio 3.1 Canary 6

Thank you all for your time.

Could not resolve in Android Studio new project

This issue seems to like the following.

How to resolve repository certificate error in Gradle build

Below steps may help:

1. Add certificate to keystore-

Import some certifications into Android Studio JDK cacerts from Android Studio’s cacerts.

Android Studio’s cacerts may be located in


I used the following import command.

$ keytool -importkeystore -v -srckeystore {src cacerts} -destkeystore {dest cacerts}

2. Add modified cacert path to{your-android-studio-directory}\\jre\\jre\\lib\\security\\cacerts

Ref :

No provider for HttpClient

In angular github page, this problem was discussed and found solution.

Failed to resolve: (Dependency Error)

If you are using Android Studio 3.0 or above make sure your project build.gradle should have content similar to-

buildscript {                 
    repositories {
    dependencies {            
        classpath ''


allprojects {
    repositories {

Note- position really matters add google() before jcenter()

And for below Android Studio 3.0 and starting from support libraries 26.+ your project build.gradle must look like this-

allprojects {
    repositories {
        maven {
            url ""

check these links below for more details-

1- Building Android Apps

2- Add Build Dependencies

3- Configure Your Build

Android Studio 3.0 Execution failed for task: unable to merge dex

I also got the similar error.

Problem :

enter image description here

Solution :

Main root cause for this issue ismultiDex is not enabled. So in the Project/android/app/build.gradle, enable the multiDex

For further information refer the documentation:

enter image description here

Unable to merge dex

In my case, Unfortunately, neither Michel's nor Suragch's solutions worked for me.

So I solved this issue by doing the following:

In gradle:3.0 the compile configuration is now deprecated and should be replaced by implementation or api. For more information you can read here You can read the official docs at Gradle Build Tool

The compile configuration still exists but should not be used as it will not offer the guarantees that the api and implementation configurations provide.

it's better to use implementation or api rather compile

just replace compile with implementation, debugCompile with debugImplementation, testCompile with testImplementation and androidtestcompile with androidTestImplementation

For example: Instead of this

compile ''
compile ''
compile 'com.github.bumptech.glide:glide:4.0.0'

use like this

implementation ''
implementation ''
implementation 'com.github.bumptech.glide:glide:4.0.0'

After that

  • Delete the .gradle folder inside your project ( Note that, in order to see .gradle, you need to switch to the "Project" view in the navigator on the top left )
  • Delete all the build folders and the gradle cache.
  • From the Build menu, press the Clean Project button.
  • After task completed, press the Rebuild Project button from the Build menu.

Hope it will helps !

Django - Reverse for '' not found. '' is not a valid view function or pattern name

Add store name to template like {% url 'app_name:url_name' %}

App_name = store

In, path('search', views.searched, name="searched"),

<form action="{% url 'store:searched' %}" method="POST">

Refused to load the font 'data:font/woff.....'it violates the following Content Security Policy directive: "default-src 'self'". Note that 'font-src'

In my case, I deleted src/registerServiceWorker file from create-react-app generated app. I added it and now it's all working.

Failed to resolve:

Can you control internet access ? If you dont have internet access, your ide doesnt download package then you encountered this problem.

ESLint not working in VS Code?

I use Use Prettier Formatter and ESLint VS Code extension together for code linting and formating.

enter image description here

enter image description here

now install some packages using given command, if more packages required they will show with installation command as an error in the terminal for you, please install them also.

npm i eslint prettier eslint@^5.16.0 eslint-config-prettier eslint-plugin-prettier eslint-config-airbnb eslint-plugin-node eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-react eslint-plugin-react-hooks@^2.5.0 --save-dev

now create a new file name .prettierrc in your project home directory, using this file you can configure settings of the prettier extension, my settings are below:

  "singleQuote": true

now as for the ESlint you can configure it according to your requirement, I am advising you to go Eslint website see the rules (

Now create a file name .eslintrc.json in your project home directory, using that file you can configure eslint, my configurations are below:

  "extends": ["airbnb", "prettier", "plugin:node/recommended"],
  "plugins": ["prettier"],
  "rules": {
    "prettier/prettier": "error",
    "spaced-comment": "off",
    "no-console": "warn",
    "consistent-return": "off",
    "func-names": "off",
    "object-shorthand": "off",
    "no-process-exit": "off",
    "no-param-reassign": "off",
    "no-return-await": "off",
    "no-underscore-dangle": "off",
    "class-methods-use-this": "off",
    "prefer-destructuring": ["error", { "object": true, "array": false }],
    "no-unused-vars": ["error", { "argsIgnorePattern": "req|res|next|val" }]

Android dependency has different version for the compile and runtime

    configurations.all {_x000D_
        //here put the library that made the error with the version you want to use_x000D_

add this to gradle (project) inside allprojects

ReactJS lifecycle method inside a function Component

If you need use React LifeCycle, you need use Class.


import React, { Component } from 'react';

class Grid extends Component {


 componentDidMount () { /* do something */ }

 render () { 
   return <h1>Hello</h1>


Setting up Gradle for api 26 (Android)

Appears to be resolved by Android Studio 3.0 Canary 4 and Gradle 3.0.0-alpha4.

More than one file was found with OS independent path 'META-INF/LICENSE'

For me below solution worked you may get help too, I wrote below line in app's gradle file

  packagingOptions {
        exclude 'META-INF/proguard/'

Android Studio - Failed to notify project evaluation listener error

I have met the similar problem.

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':app'.
> Failed to notify project evaluation listener.
   > org.gradle.api.tasks.compile.CompileOptions.setBootClasspath(Ljava/lang/String;)V

* Try:
Run with --stacktrace option to get the stack trace. Run with --debug option to get more log output. Run with --scan to get full insights.

* Get more help at

Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0.
Use '--warning-mode all' to show the individual deprecation warnings.

Build step 'Invoke Gradle script' changed build result to FAILURE
Build step 'Invoke Gradle script' marked build as failure
Finished: FAILURE

The key is you need to get a way to solve this kind of problems,not to solve this problem.

According to the log above,the most important information is:

Run with --stacktrace option to get the stack trace. Run with --debug option to get more log output. Run with --scan to get full insights.

Most of the building problems of Gradle will be solved because when you use the specific Gradle build command,you can get more detailed and useful information that are clear.

*clean project
./gradlew clean  

*build project
./gradlew build

*build for debug package
./gradlew assembleDebug or ./gradlew aD

*build for release package
./gradlew assembleRelease or ./gradlew aR

*build for release package and install
./gradlew installRelease or ./gradlew iR Release

*build for debug package and install
./gradlew installDebug or ./gradlew iD Debug

*uninstall release package
./gradlew uninstallRelease or ./gradlew uR

*uninstall debug package
./gradlew uninstallDebug or ./gradlew uD 

*all the above command + "--info" or "--debug" or "--scan" or "--stacktrace" can get more detail information.

And then I found the problem is related with the version of Gradle,when I have changed Gradle from 5.0 to 4.1,and then it's OK.

Error:Execution failed for task ':app:compileDebugKotlin'. > Compilation error. See log for more details

On Mac :

go to Android Studio > Preferences > Build, Execution, Deployment > Compiler

On Windows :

go to File > Settings > > Build, Execution, Deployment > Compiler

Now, in the Command-line Options field , add following three flags :

--stacktrace --info --scan

like shown below

enter image description here

Now , open the Build window from the bottom of Android studio enter image description here

Then, there is a button on the left side of the Build window:

enter image description here

press this button , you will see detailed logs with exact code that is preventing the project from compiling

Angular 4 default radio button checked by default

getting following error

It happens:  Error: 
      ngModel cannot be used to register form controls with a parent formGroup directive.  Try using
      formGroup's partner directive "formControlName" instead.  Example:

I am getting an "Invalid Host header" message when connecting to webpack-dev-server remotely

Hello React Developers,

Instead of doing this disableHostCheck: true, in webpackDevServer.config.js. You can easily solve 'invalid host headers' error by adding a .env file to you project, add the variables HOST= and DANGEROUSLY_DISABLE_HOST_CHECK=true in .env file. If you want to make changes in webpackDevServer.config.js, you need to extract the react-scripts by using 'npm run eject' which is not recommended to do it. So the better solution is adding above mentioned variables in .env file of your project.

Happy Coding :)

How to disable a ts rule for a specific line?


TS 3.9 introduces a new magic comment. @ts-expect-error will:

  • have same functionality as @ts-ignore
  • trigger an error, if actually no compiler error has been suppressed (= indicates useless flag)
if (false) {
  // @ts-expect-error: Let's ignore a single compiler error like this unreachable code 
  console.log("hello"); // compiles

// If @ts-expect-error didn't suppress anything at all, we now get a nice warning 
let flag = true;
// ...
if (flag) {
  // @ts-expect-error
  // ^~~~~~~~~~~~~~~^ error: "Unused '@ts-expect-error' directive.(2578)"


@ts-ignore and @ts-expect-error can be used for all sorts of compiler errors. For type issues (like in OP), I recommend one of the following alternatives due to narrower error suppression scope:

? Use any type

// type assertion for single expression
delete ($ as any).summernote.options.keyMap.pc.TAB;

// new variable assignment for multiple usages
const $$: any = $
delete $$.summernote.options.keyMap.pc.TAB;
delete $$.summernote.options.keyMap.mac.TAB;

? Augment JQueryStatic interface

// ./global.d.ts
interface JQueryStatic {
  summernote: any;

// ./main.ts
delete $.summernote.options.keyMap.pc.TAB; // works

In other cases, shorthand module declarations or module augmentations for modules with no/extendable types are handy utilities. A viable strategy is also to keep not migrated code in .js and use --allowJs with checkJs: false.

How to Install Font Awesome in Laravel Mix

Solution for Laravel 7

  1. Install font-awesome library.
npm install font-awesome --save
  1. After installing the library. Open the following file and paste given code


@import "~font-awesome/scss/font-awesome";
  1. Open the following file and paste given code


  1. As per your environment execute command.

npm run dev


npm run production

There is no need to copy and paste the font folder to the public folder, all will be handled automatically.

Draw horizontal rule in React Native

import {Dimensions} from 'react-native'

const { width, height } = Dimensions.get('window')

         borderBottomColor: '#1D3E5E',
         borderBottomWidth: 1,
         width : width , 

Gradle error: Minimum supported Gradle version is 3.3. Current version is 3.2

For Android Studion version 3.3.2

1) I updated the gradle distribution URL to distributionUrl=https\:// in file

2) Within the top-level build.gradle file updated the gradle plugin to version 3.3.2

dependencies {
    classpath ''
    classpath ''

Field 'browser' doesn't contain a valid alias configuration

In my case, it is due to a case-sensitivity typo in import path. For example,

Should be:

import Dashboard from './Dashboard/dashboard';

Instead of:

import Dashboard from './Dashboard/Dashboard';

Error:Cause: unable to find valid certification path to requested target

If you are running behind a corporate proxy with SSL interception, you will need to follow these steps to trust your proxy certificate for HTTPS:

  • In Android Studio, Open File -> Settings
    • In Tools -> Server Certificates
      • Tick ‘Accept non-trusted certificates automatically’
      • Also click the ‘+’ and manually add the corporate proxy root certificate.
    • In Appearance and Behaviour -> System Settings -> HTTP Proxy
      • Set your corporate proxy URL and port details
  • Download KeyStore Explorer:
  • In KeyStore Explorer (run as admin), open the Android Studio JRE certificate store: C:\Program Files\Android\Android Studio\jre\jre\lib\security\cacerts
    • The password should be ‘changeit’
    • Import the corporate proxy root certificate, and save.
  • In Android Studio, select File -> Invalidate Cache and Restart

In Typescript, what is the ! (exclamation mark / bang) operator when dereferencing a member?

non-null assertion operator

With the non-null assertion operator we can tell the compiler explicitly that an expression has value other than null or undefined. This is can be useful when the compiler cannot infer the type with certainty but we more information than the compiler.


TS code

function simpleExample(nullableArg: number | undefined | null) {
   const normal: number = nullableArg; 
    //   Compile err: 
    //   Type 'number | null | undefined' is not assignable to type 'number'.
    //   Type 'undefined' is not assignable to type 'number'.(2322)

   const operatorApplied: number = nullableArg!; 
    // compiles fine because we tell compiler that null | undefined are excluded 

Compiled JS code

Note that the JS does not know the concept of the Non-null assertion operator since this is a TS feature

"use strict";
function simpleExample(nullableArg) {
    const normal = nullableArg;
    const operatorApplied = nullableArg;

Disable eslint rules for folder

The previous answers were in the right track, but the complete answer for this is going to Disabling rules only for a group of files, there you'll find the documentation needed to disable/enable rules for certain folders (Because in some cases you don't want to ignore the whole thing, only disable certain rules). Example:

    "env": {},
    "extends": [],
    "parser": "",
    "plugins": [],
    "rules": {},
    "overrides": [
        "files": ["test/*.spec.js"], // Or *.test.js
        "rules": {
          "require-jsdoc": "off"
    "settings": {}

Error retrieving parent for item: No resource found that matches the given name 'android:TextAppearance.Material.Widget.Button.Borderless.Colored'

Solution for me (Android Studio) :

1) Use shortcut Ctrl+Shift+Alt+S or File -> Project Structure

2) and increase the level of SDK "Compile SDK Version".

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema

I had webpack version 3 so I installed webpack-dev-server version 2.11.5 according to current "Versions" page. And then the problem was gone.

enter image description here

Remove from the beginning of std::vector

Two suggestions:

  1. Use std::deque instead of std::vector for better performance in your specific case and use the method std::deque::pop_front().
  2. Rethink (I mean: delete) the & in std::vector<ScanRule>& topPriorityRules;

JUnit 5: How to assert an exception is thrown?

You can use assertThrows(), But with assertThrows your assertion will pass even if the thrown exception is of child type.

This is because, JUnit 5 checks exception type by calling Class.isIntance(..), Class.isInstance(..) will return true even if the exception thrown is of the child types.

The workaround for this is to assert on Class:

Throwable throwable =  assertThrows(Throwable.class, () -> {
assertEquals(FileNotFoundException.class, throwable.getClass());

Plugin with id '' not found

Go To Setting > Android SDK > SDK Tools > Google Play Services

enter image description here

Didn't find class ""?

This is due to MultiDex.

Steps to solve:

  1. In gradle->dependencies->(compile'') Add this in dependencies

  2. In your project application class extends MultiDexApplication like this (public class MyApplication extends MultiDexApplication)

  3. Run and check

How to beautifully update a JPA entity in Spring Data?

I have encountered this issue!
Luckily, I determine 2 ways and understand some things but the rest is not clear.
Hope someone discuss or support if you know.

  1. Use
    List<Person> person = this.PersonRepository.findById(0) person.setName("Neo");;
    this block code updated new name for record which has id = 0;
  2. Use @Transactional from javax or spring framework.
    Let put @Transactional upon your class or specified function, both are ok.
    I read at somewhere that this annotation do a "commit" action at the end your function flow. So, every things you modified at entity would be updated to database.

Make the size of a heatmap bigger with seaborn

I do not know how to solve this using code, but I do manually adjust the control panel at the right bottom in the plot figure, and adjust the figure size like:

f, ax = plt.subplots(figsize=(16, 12))

at the meantime until you get a matched size colobar. This worked for me.

React eslint error missing in props validation

It seems that the problem is in eslint-plugin-react.

It can not correctly detect what props were mentioned in propTypes if you have annotated named objects via destructuring anywhere in the class.

There was similar problem in the past

Numpy: Checking if a value is NaT

Very simple and surprisingly fast: (without numpy or pandas)

    str( myDate ) == 'NaT'            # True if myDate is NaT

Ok, it's a little nasty, but given the ambiguity surrounding 'NaT' it does the job nicely.

It's also useful when comparing two dates either of which might be NaT as follows:

   str( date1 ) == str( date1 )       # True
   str( date1 ) == str( NaT )         # False
   str( NaT )   == str( date1 )       # False

wait for it...

   str( NaT )   == str( Nat )         # True    (hooray!)

How to dynamically add and remove form fields in Angular 2

That is the HTML code. Anyone can use this:

<div class="card-header">Contact Information</div>
          <div class="card-body" formArrayName="funds">
            <div class="row">
              <div class="col-6" *ngFor="let contact of contactFormGroup.controls; let i = index;">
                <div [formGroupName]="i" class="row">
                  <div class="form-group col-6">
                    <label>Type of Contact</label>
                    <select class="form-control" formControlName="fundName" type="text">
                      <option value="01">Balance Fund</option>
                      <option value="02">Equity Fund</option>
                  <div class="form-group col-12">
                    <input class="form-control" formControlName="allocation" type="number">
                    <span class="text-danger" *ngIf="getContactsFormGroup(i).controls['allocation'].touched && 
                        Allocation % is required! </span>
                  <div class="form-group col-12 text-right">
                    <button class="btn btn-danger" type="button" (click)="removeContact(i)"> Remove </button>
          <button class="btn btn-primary m-1" type="button" (click)="addContact()"> Add Contact </button>

IE and Edge fix for object-fit: cover;

There is no rule to achieve that using CSS only, besides the object-fit (that you are currently using), which has partial support in EDGE1 so if you want to use this in IE, you have to use a object-fit polyfill in case you want to use just the element img, otherwise you have to do some workarounds.

You can see the the object-fit support here


You can use a simple JS snippet to detect if the object-fit is supported and then replace the img for a svg

//ES6 version
if ('objectFit' in === false) {
    document.addEventListener('DOMContentLoaded', () => {
        document.querySelectorAll('img[data-object-fit]').forEach(image => {
            (image.runtimeStyle || = `url("${image.src}") no-repeat 50%/${image.currentStyle ? image.currentStyle['object-fit'] : image.getAttribute('data-object-fit')}`
            image.src = `data:image/svg+xml,%3Csvg xmlns='' width='${image.width}' height='${image.height}'%3E%3C/svg%3E`

//ES5 version transpiled from code above with BabelJS
if ('objectFit' in === false) {
    document.addEventListener('DOMContentLoaded', function() {
        document.querySelectorAll('img[data-object-fit]').forEach(function(image) {
            (image.runtimeStyle || = "url(\"".concat(image.src, "\") no-repeat 50%/").concat(image.currentStyle ? image.currentStyle['object-fit'] : image.getAttribute('data-object-fit'));
            image.src = "data:image/svg+xml,%3Csvg xmlns='' width='".concat(image.width, "' height='").concat(image.height, "'%3E%3C/svg%3E");
img {
  display: inline-flex;
  width: 175px;
  height: 175px;
  margin-right: 10px;
  border: 1px solid red

[data-object-fit='cover'] {
  object-fit: cover

[data-object-fit='contain'] {
  object-fit: contain
<img data-object-fit='cover' src='//' />
<img data-object-fit='contain' src='//' />
<img src='//' />


1 - EDGE has now partial support for object-fit since version 16, and by partial, it means only works in img element (future version 18 still has only partial support)


Use virtualenv with Python with Visual Studio Code in Ubuntu

With the latest Python extension for Visual Studio Code, there is a venvPath Setting:

// Path to folder with a list of Virtual Environments (e.g. ~/.pyenv, ~/Envs, ~/.virtualenvs).
  "python.venvPath": "",

On Mac OS X, go to Code ? Preferences ? Settings and scroll down to Python Configuration.

Look for "python.venvPath: "", and click the pencil on the left-hand side to open up your user settings. Finally, add the path to where you store your virtual environments.

If you are using virtuanenvwrapper, or you have put all your virtual environment setting in one folder, this will be the one for you.

After you have configured "python.venvPath", restart Visual Studio Code. Then open the command palette and look for "Python: Select Interpreter". At this point, you should see the interpreter associated with the virtual environment you just added.

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformClassesWithDexForDebug'

you just change import; to import;

and extends AppCompatActivity

How to Validate on Max File Size in Laravel?

According to the documentation:

$validator = Validator::make($request->all(), [
    'file' => 'max:500000',

The value is in kilobytes. I.e. max:10240 = max 10 MB.

Firebase Permission Denied

Go to database, next to title there are 2 options:

Cloud Firestore, Realtime database

Select Realtime database and go to rules

Change rules to true.

Error:Conflict with dependency ''

In your app's build.gradle add the following:

android {
    configurations.all {
        resolutionStrategy.force ''

Enforces Gradle to only compile the version number you state for all dependencies, no matter which version number the dependencies have stated.

Android Studio - Failed to apply plugin [id '']

Whenever you update your Gradle files do not forget to check the compatible Gradle wrapper distibutionUrl, in your case it happened because of the same.


Checkbox value true/false

To return true or false depending on whether a checkbox is checked or not, I use this in JQuery

let checkState = $("#checkboxId").is(":checked") ? "true" : "false";

How do I turn off the mysql password validation?

If you want to make exceptions, you can apply the following "hack". It requires a user with DELETE and INSERT privilege for mysql.plugin system table.

uninstall plugin validate_password;
INSTALL PLUGIN validate_password SONAME '';

Bland security disclaimer: Consider, why you are making your password shorter or easier and perhaps consider replacing it with one that is more complex. However, I understand the "it's 3AM and just needs to work" moments, just make sure you don't build a system of hacks, lest you yourself be hacked

Making a flex item float right

You don't need floats. In fact, they're useless because floats are ignored in flexbox.

You also don't need CSS positioning.

There are several flex methods available. auto margins have been mentioned in another answer.

Here are two other options:

  • Use justify-content: space-between and the order property.
  • Use justify-content: space-between and reverse the order of the divs.

.parent {_x000D_
    display: flex;_x000D_
    justify-content: space-between;_x000D_
.parent:first-of-type > div:last-child { order: -1; }_x000D_
p { background-color: #ddd;}
<p>Method 1: Use <code>justify-content: space-between</code> and <code>order-1</code></p>_x000D_
<div class="parent">_x000D_
    <div class="child" style="float:right"> Ignore parent? </div>_x000D_
    <div>another child </div>_x000D_
<p>Method 2: Use <code>justify-content: space-between</code> and reverse the order of _x000D_
             divs in the mark-up</p>_x000D_
<div class="parent">_x000D_
    <div>another child </div>_x000D_
    <div class="child" style="float:right"> Ignore parent? </div>_x000D_

Android Error Building Signed APK: keystore.jks not found for signing config 'externalOverride'

File -> Invalidate Caches & Restart...

Build -> Build signed APK -> check the path in the dialog

Check the key store path

ESLint Parsing error: Unexpected token

I solved this issue by First, installing babel-eslint using npm

npm install babel-eslint --save-dev

Secondly, add this configuration in .eslintrc file


Numpy isnan() fails on an array of floats (from pandas dataframe apply)

Make sure you import csv file using Pandas

import pandas as pd

condition = pd.isnull(data[i][j])

Android- Error:Execution failed for task ':app:transformClassesWithDexForRelease'

I got this error When upgrading Google play services to 9.0 from 7.5

Having error with below one:

compile ''

When I changed to

compile ''

There is no error. Try this

How to make Bootstrap 4 cards the same height in card-columns?

You can either put the classes on the "row" or the "column"? Won't be visible on the cards (border) if you use it on the row.

<div class="container">
    <div class="row">
          <div class="col-lg-4 d-flex align-items-stretch">

Some of the other answers here seem 'wacky'. Why would use a min-height or even worse a fixed height?

I thought this issue (equal heights) was part of the reason for progression away from floating block divs?

Manifest Merger failed with multiple errors in Android Studio

  1. In AndroidManifest.xml:

    • At application, add tools:replace="android:icon, android:theme and
    • At the Manifest root, add xmlns:tools="
  2. In build.gradle:

    • At root, add useOldManifestMerger true

Error:Execution failed for task ':app:processDebugResources'. > Could not delete folder "" in android studio

In my case it was that you had the app installed and when you gave it react-native run-android I could not install the app since it was already previously installed

"No rule to make target 'install'"... But Makefile exists

I was receiving the same error message, and my issue was that I was not in the correct directory when running the command make install. When I changed to the directory that had my makefile it worked.

So possibly you aren't in the right directory.

ActivityCompat.requestPermissions not showing dialog box

Maybe this solution could help anyone rather than:

ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);

use :

ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);

so we add android. to Manifest.permission.WRITE_EXTERNAL_STORAGE

How can I have same rule for two locations in NGINX config?

Both the regex and included files are good methods, and I frequently use those. But another alternative is to use a "named location", which is a useful approach in many situations — especially more complicated ones. The official "If is Evil" page shows essentially the following as a good way to do things:

error_page 418 = @common_location;
location /first/location/ {
    return 418;
location /second/location/ {
    return 418;
location @common_location {
    # The common configuration...

There are advantages and disadvantages to these various approaches. One big advantage to a regex is that you can capture parts of the match and use them to modify the response. Of course, you can usually achieve similar results with the other approaches by either setting a variable in the original block or using map. The downside of the regex approach is that it can get unwieldy if you want to match a variety of locations, plus the low precedence of a regex might just not fit with how you want to match locations — not to mention that there are apparently performance impacts from regexes in some cases.

The main advantage of including files (as far as I can tell) is that it is a little more flexible about exactly what you can include — it doesn't have to be a full location block, for example. But it's also just subjectively a bit clunkier than named locations.

Also note that there is a related solution that you may be able to use in similar situations: nested locations. The idea is that you would start with a very general location, apply some configuration common to several of the possible matches, and then have separate nested locations for the different types of paths that you want to match. For example, it might be useful to do something like this:

location /specialpages/ {
    # some config
    location /specialpages/static/ {
        try_files $uri $uri/ =404;
    location /specialpages/dynamic/ {

Error: No toolchains found in the NDK toolchains folder for ABI with prefix: llvm

I navigated to, and in there the


line needs to be updated to where your ndk lies.

I was using Crystax NDK, and didn't realize the original Android NDK was still in use.

android: data binding error: cannot find symbol class

make all your packages name's in the project that you used in binding to lower case.

Turning off eslint rule for a specific file

To disable a specific rule for the file:

/* eslint-disable no-use-before-define */

Note there is a bug in eslint where single line comment will not work -

// eslint-disable max-classes-per-file
// This fails!

Check this post

Android Studio Gradle: Error:Execution failed for task ':app:processDebugGoogleServices'. > No matching client found for package

Open google-services.json in android studio we can see a json object, and contain following items in 'client' jsonarray

"client_id": "android:your package name", "package_name": "your package name",

Please verify your package and proceed.

HTTP 415 unsupported media type error when calling Web API 2 endpoint

After banging my head on the wall for a couple days with this issue, it was looking like the problem had something to do with the content type negotiation between the client and server. I dug deeper into that using Fiddler to check the request details coming from the client app, here's a screenshot of the raw request as captured by fiddler:

Fiddler capture of http request from client app

What's obviously missing there is the Content-Type header, even though I was setting it as seen in the code sample in my original post. I thought it was strange that the Content-Type never came through even though I was setting it, so I had another look at my other (working) code calling a different Web API service, the only difference was that I happened to be setting the req.ContentType property prior to writing to the request body in that case. I made that change to this new code and that did it, the Content-Type was now showing up and I got the expected success response from the web service. The new code from my .NET client now looks like this:

req.Method = "POST"
req.ContentType = "application/json"
lstrPagingJSON = JsonSerializer(Of Paging)(lPaging)
bytData = Encoding.UTF8.GetBytes(lstrPagingJSON)
req.ContentLength = bytData.Length
reqStream = req.GetRequestStream()
reqStream.Write(bytData, 0, bytData.Length)
'// Content-Type was being set here, causing the problem
'req.ContentType = "application/json"

That's all it was, the ContentType property just needed to be set prior to writing to the request body

I believe this behavior is because once content is written to the body it is streamed to the service endpoint being called, any other attributes pertaining to the request need to be set prior to that. Please correct me if I'm wrong or if this needs more detail.

Could not determine the dependencies of task ':app:crashlyticsStoreDeobsDebug' if I enable the proguard

I had the same issue a few days ago and I found this thread Twitter Developer Forum that points to some incompatibility with versions of gradle/build-tools/crashalics.

My problem was slightly different from yours as I'm not using alpha-3 I'm using 1.5. But on my update I also changed to the latest gradle distribution

So probably/maybe you can fix it by changing to the latest gradle version. But If it does not work, you'll really have to be patient and wait until build tools V2.0 is not in alpha anymore OR the Crashalitycs team, fix the incompatibility.

Eslint: How to disable "unexpected console statement" in Node.js?

My 2 cents contribution:

Besides removing the console warning (as shown above), it's best to remove yours logs from PROD environments (for security reasons). The best way I found to do so, is by adding this to nuxt.config.js

  build: {
   terser: {
      terserOptions: {
        compress: {
          //this removes console.log from production environment
          drop_console: true

How it works: Nuxt already uses terser as minifier. This config will force terser to ignore/remove all console logs commands during compression.

How to set adaptive learning rate for GradientDescentOptimizer?

If you want to set specific learning rates for intervals of epochs like 0 < a < b < c < .... Then you can define your learning rate as a conditional tensor, conditional on the global step, and feed this as normal to the optimiser.

You could achieve this with a bunch of nested tf.cond statements, but its easier to build the tensor recursively:

def make_learning_rate_tensor(reduction_steps, learning_rates, global_step):
    assert len(reduction_steps) + 1 == len(learning_rates)
    if len(reduction_steps) == 1:
        return tf.cond(
            global_step < reduction_steps[0],
            lambda: learning_rates[0],
            lambda: learning_rates[1]
        return tf.cond(
            global_step < reduction_steps[0],
            lambda: learning_rates[0],
            lambda: make_learning_rate_tensor(

Then to use it you need to know how many training steps there are in a single epoch, so that we can use the global step to switch at the right time, and finally define the epochs and learning rates you want. So if I want the learning rates [0.1, 0.01, 0.001, 0.0001] during the epoch intervals of [0, 19], [20, 59], [60, 99], [100, \infty] respectively, I would do:

global_step = tf.train.get_or_create_global_step()
learning_rates = [0.1, 0.01, 0.001, 0.0001]
steps_per_epoch = 225
epochs_to_switch_at = [20, 60, 100]
epochs_to_switch_at = [x*steps_per_epoch for x in epochs_to_switch_at ]
learning_rate = make_learning_rate_tensor(epochs_to_switch_at , learning_rates, global_step)

Error:Execution failed for task ':app:transformClassesWithDexForDebug'

just remove both build folder in /android and /android/app

and build again with react-native run-android

Gradle Error:Execution failed for task ':app:processDebugGoogleServices'

In my case when i was using firebase services the google.json file was mismatched check once that also

failed to find target with hash string android-23

The answer to this question.

Gradle gets stupid from time to time and wiping out the cache is the only solution that I've found. You'll find a hidden .gradle folder under your user home folder and another one wherever the checkout location is for osmdroid.

Execution Failed for task :app:compileDebugJavaWithJavac in Android Studio

I faced this issue after upgrading the Android studio to version 2.2.2, I solved it by using embedded JDK as recommended : enter image description here

Conflict with dependency ''. Resolved versions for app (23.1.0) and test app (23.0.1) differ

I was getting the same error today:

Error:Execution failed for task ':app:preDebugAndroidTestBuild'.> Conflict with dependency '' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ.

What I did:

  • I simply updated all my dependencies to 27.1.1 instead of 26.1.0
  • Also, updated my compileSdkVersion 27 and targetSdkVersion 27 which were 26 earlier

And error was gone!

For Ref:

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation ''
    implementation ''
    implementation ''
    testImplementation 'junit:junit:4.12'
    androidTestImplementation ''
    androidTestImplementation ''

Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug'

There may be different reason for reported issue, few days back also face this issue 'duplicate jar', after upgrading studio. From all stackoverflow I tried all the suggestion but nothing worked for me.

But this is for sure some duplicate jar is there, For me it was present in one library libs folder as well as project libs folder. So I removed from project libs folder as it was not required here. So be careful while updating the studio, and try to understand all the gradle error.

Cannot resolve symbol HttpGet,HttpClient,HttpResponce in Android Studio

For me, the below helped

Find org.apache.http.legacy.jar which is in Android/Sdk/platforms/android-23/optional, add it to your dependency.


Error:(23, 17) Failed to resolve: junit:junit:4.12

I had the same problem, but with another problem.

My other problem was that the Gradle build was too slow!

I resolved my problem by doing thisL

If you do like mdew you need to this any time you're creating your project to do this

So if you want to set default option to maven

Do this:

Go to the folder:

C:\Program Files\Android\Android Studio\plugins\android\lib\templates\gradle-projects\NewAndroidProject\root

Then open the build.gradle.ftl file with notepad++ or notepad and replace all jcenter() with mavenCentral().

EDIT: Why its going down voted? you don't like it?

WARNING: Exception encountered during context initialization - cancelling refresh attempt

  1. To closed ideas,
  2. To remove all folder and file C:/Users/UserName/.m2/org/*,
  3. Open ideas and update Maven project,(right click on project -> maven->update maven project)
  4. After that update the project.

Android appcompat v7:23

Ran into a similar issue using React Native

> Could not find

the Support Libraries are Local Maven repository for Support Libraries

enter image description here

Use .htaccess to redirect HTTP to HTTPs

Nothing of the above worked for me. But those lines solved the same problem on my WordPress site:

RewriteEngine On

RewriteCond %{HTTP:HTTPS} !on
RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

How to use ESLint with Jest

You can also set the test env in your test file as follows:

/* eslint-env jest */

describe(() => {
  /* ... */

Getting a 500 Internal Server Error on Laravel 5+ Ubuntu 14.04

I fixed this problem by this commands:

mv .env.example .env
php artisan cache:clear
composer dump-autoload
php artisan key:generate


php artisan serve

Laravel password validation rule

I have had a similar scenario in Laravel and solved it in the following way.

The password contains characters from at least three of the following five categories:

  • English uppercase characters (A – Z)
  • English lowercase characters (a – z)
  • Base 10 digits (0 – 9)
  • Non-alphanumeric (For example: !, $, #, or %)
  • Unicode characters

First, we need to create a regular expression and validate it.

Your regular expression would look like this:


I have tested and validated it on this site. Yet, perform your own in your own manner and adjust accordingly. This is only an example of regex, you can manipluated the way you want.

So your final Laravel code should be like this:

'password' => 'required|

Update As @NikK in the comment mentions, in Laravel 5.5 and newer the the password value should encapsulated in array Square brackets like

'password' => ['required', 

I have not testing it on Laravel 5.5 so I am trusting @NikK hence I have moved to working with c#/.net these days and have no much time for Laravel.


  1. I have tested and validated it on both the regular expression site and a Laravel 5 test environment and it works.
  2. I have used min:6, this is optional but it is always a good practice to have a security policy that reflects different aspects, one of which is minimum password length.
  3. I suggest you to use password confirmed to ensure user typing correct password.
  4. Within the 6 characters our regex should contain at least 3 of a-z or A-Z and number and special character.
  5. Always test your code in a test environment before moving to production.
  6. Update: What I have done in this answer is just example of regex password

Some online references

Regarding your custom validation message for the regex rule in Laravel, here are a few links to look at:

How do I find an array item with TypeScript? (a modern, easier way)

If you need some es6 improvements not supported by Typescript, you can target es6 in your tsconfig and use Babel to convert your files in es5.

When do I use path params vs. query params in a RESTful API?

The fundamental way to think about this subject is as follows:

A URI is a resource identifier that uniquely identifies a specific instance of a resource TYPE. Like everything else in life, every object (which is an instance of some type), have set of attributes that are either time-invariant or temporal.

In the example above, a car is a very tangible object that has attributes like make, model and VIN - that never changes, and color, suspension etc. that may change over time. So if we encode the URI with attributes that may change over time (temporal), we may end up with multiple URIs for the same object:

GET /cars/honda/civic/coupe/{vin}/{color=red}

And years later, if the color of this very same car is changed to black:

GET /cars/honda/civic/coupe/{vin}/{color=black}

Note that the car instance itself (the object) has not changed - it's just the color that changed. Having multiple URIs pointing to the same object instance will force you to create multiple URI handlers - this is not an efficient design, and is of course not intuitive.

Therefore, the URI should only consist of parts that will never change and will continue to uniquely identify that resource throughout its lifetime. Everything that may change should be reserved for query parameters, as such:

GET /cars/honda/civic/coupe/{vin}?color={black}

Bottom line - think polymorphism.

How do I enable logging for Spring Security?

Assuming you're using Spring Boot, another option is to put the following in your

This is the same for most other Spring modules as well.

If you're not using Spring Boot, try setting the property in your logging configuration, e.g. logback.

Here is the application.yml version as well:

        security: DEBUG

Execution failed for task 'app:mergeDebugResources' Crunching Cruncher....png failed

I fixed this issue by moving the project to the outer directory, and it then compiled successfully.

It was due to the long path of the project directory.

For example, I moved the project from:




ESLint - "window" is not defined. How to allow global variables in package.json

I'm aware he's not asking for the inline version. But since this question has almost 100k visits and I fell here looking for that, I'll leave it here for the next fellow coder:

Make sure ESLint is not run with the --no-inline-config flag (if this doesn't sound familiar, you're likely good to go). Then, write this in your code file (for clarity and convention, it's written on top of the file but it'll work anywhere):

/* eslint-env browser */

This tells ESLint that your working environment is a browser, so now it knows what things are available in a browser and adapts accordingly.

There are plenty of environments, and you can declare more than one at the same time, for example, in-line:

/* eslint-env browser, node */

If you are almost always using particular environments, it's best to set it in your ESLint's config file and forget about it.

From their docs:

An environment defines global variables that are predefined. The available environments are:

  • browser - browser global variables.
  • node - Node.js global variables and Node.js scoping.
  • commonjs - CommonJS global variables and CommonJS scoping (use this for browser-only code that uses Browserify/WebPack).
  • shared-node-browser - Globals common to both Node and Browser.


Besides environments, you can make it ignore anything you want. If it warns you about using console.log() but you don't want to be warned about it, just inline:

/* eslint-disable no-console */

You can see the list of all rules, including recommended rules to have for best coding practices.

Vertical rulers in Visual Studio Code

Visual Studio Code: Version 1.14.2 (1.14.2)

  1. Press Shift + Command + P to open panel
    • For non-macOS users, press Ctrl+P
  2. Enter "settings.json" to open setting files.
  3. At default setting, you can see this:

    // Columns at which to show vertical rulers
    "editor.rulers": [],

    This means the empty array won't show the vertical rulers.

  4. At right window "user setting", add the following:

    "editor.rulers": [140]

Save the file, and you will see the rulers.

Execution failed for task ':app:compileDebugAidl': aidl is missing

I am working with sdk 23.1.0 and gradle 1.3.1. I created a new project edited nothing and got the aidl error. I went into my project gradle file and changed tool to 22.0.1 instead of 23.1.0 and it worked:

   compileSdkVersion 23
   buildToolsVersion "22.0.1" //"23.1.0"

Java finished with non-zero exit value 2 - Android Gradle

Just in case if someone still struggling with this and have no clue why is this happening and how to fix. In fact this error

Error:Execution failed for task ':app:dexDebug'. > org.gradle.process.internal.ExecException: Process 'command 'C:\Program Files\Java\jdkx.x.x_xx\bin\java.exe'' finished with non-zero exit value 2

can have many reasons to happen but certainly not something related to your JDK version so don't wast your time in wrong direction. These are two main reasons for this to happen

  1. You have same library or jar file included several places and some of them conflicting with each other.
  2. You are about to or already exceeded 65k method limit

First case can be fixed as follows: Find out which dependencies you have included multiple times. In order to do this run following command in android studio terminal

gradlew -q dependencies yourProjectName_usually_app:dependencies --configuration compile

this will return all the dependencies but jar files that you include from lib folder try to get rid of duplication marked with asterisk (*), this is not always possible but in some cases you still can do it, after this try to exclude modules that are included many times, you can do it like this

compile (''){
    exclude module: 'support-v4'

For the second case when you exceeding method limit suggestion is to try to minimize it by removing included libraries (note sounds like first solution) if no way to do it add multiDexEnabled true to your defaultConfig

defaultConfig {
   multiDexEnabled true

this increases method limit but it is not the best thing to do because of possible performance issues IMPORTANT adding only multiDexEnabled true to defaultConfig is not enough in fact on all devices running android <5 Lollipop it will result in unexpected behavior and NoClassDefFoundError. how to solve it is described here

finished with non zero exit value

Make sure you choose to build a variant as 'Release' on Android Studio.

enter image description here

Plugin is too old, please update to a more recent version, or set ANDROID_DAILY_OVERRIDE environment variable to

set Environment variable ANDROID_DAILY_OVERRIDE to same value Example - b9471da4f76e0d1a88d41a072922b1e0c257745c

this works for me.

Android java.exe finished with non-zero exit value 1

After adding a jar file to a project's lib folder and after adding it to the build.gradle file as compile'path example' when you sync the gradle it add an additional line as compile files('libs/example.jar'). You just need to remove the line you previously added to the build.gradle file i.e. the compile'path example' after the gradle sync. You also need to remove the line compile fileTree(dir: 'libs', include: '*.jar')

Error:Execution failed for task ':ProjectName:mergeDebugResources'. > Crunching Cruncher *some file* failed, see logs

I was also stuck by this problem.But in my case I delete all .png images from drawable folder ,clean and rebuild application and then paste all .png images to my drawable, rebuild again. It worked fine for me.

Error:Execution failed for task ':app:dexDebug'.

It seems you have a jar file or a lib appearing multiple times.

So, remove the .jar file from the lib folder then:

Build > Rebuild

Laravel Eloquent - distinct() and count() not working properly together

Based on Laravel docs for raw queries I was able to get count for a select field to work with this code in the product model.

public function scopeShowProductCount($query)
    $query->select(DB::raw('DISTINCT pid, COUNT(*) AS count_pid'))
          ->orderBy('count_pid', 'desc');

This facade worked to get the same result in the controller:

$products = DB::table('products')->select(DB::raw('DISTINCT pid, COUNT(*) AS count_pid'))->groupBy('pid')->orderBy('count_pid', 'desc')->get();

The resulting dump for both queries was as follows:

#attributes: array:2 [
  "pid" => "1271"
  "count_pid" => 19
#attributes: array:2 [
  "pid" => "1273"
  "count_pid" => 12
#attributes: array:2 [
  "pid" => "1275"
  "count_pid" => 7

JsonParseException: Unrecognized token 'http': was expecting ('true', 'false' or 'null')

We have the following string which is a valid JSON ...

Clearly the JSON parser disagrees!

However, the exception says that the error is at "line 1: column 9", and there is no "http" token near the beginning of the JSON. So I suspect that the parser is trying to parse something different than this string when the error occurs.

You need to find what JSON is actually being parsed. Run the application within a debugger, set a breakpoint on the relevant constructor for JsonParseException ... then find out what is in the ByteArrayInputStream that it is attempting to parse.

How to resolve Value cannot be null. Parameter name: source in linq?

When you call a Linq statement like this:

// x = new List<string>();
var count = x.Count(s => s.StartsWith("x"));

You are actually using an extension method in the System.Linq namespace, so what the compiler translates this into is:

var count = Enumerable.Count(x, s => s.StartsWith("x"));

So the error you are getting above is because the first parameter, source (which would be x in the sample above) is null.

Gradle failed to resolve library in Android Studio

Solved by using "" instead of "".

repositories {
    jcenter( { url "" } )

Laravel 5 - redirect to HTTPS

You can use RewriteRule to force ssl in .htaccess same folder with your index.php
Please add as picture attach, add it before all rule others setting ssl .htaccess

Laravel 5 – Remove Public from URL

Let's say you placed all the other files and directories in a folder named 'locale'.

enter image description here

Just go to index.php and find these two lines:

require __DIR__.'/../bootstrap/autoload.php';

$app = require_once __DIR__.'/../bootstrap/app.php';

and change them to this:

require __DIR__.'/locale/bootstrap/autoload.php';

$app = require_once __DIR__.'/locale/bootstrap/app.php';

Laravel Unknown Column 'updated_at'

In the model, write the below code;

public $timestamps = false;

This would work.

Explanation : By default laravel will expect created_at & updated_at column in your table. By making it to false it will override the default setting.

Use Excel VBA to click on a button in Internet Explorer, when the button has no "name" associated

With the kind help from Tim Williams, I finally figured out the last détails that were missing. Here's the final code below.

Private Sub Open_multiple_sub_pages_from_main_page()

Dim i As Long
Dim IE As Object
Dim Doc As Object
Dim objElement As Object
Dim objCollection As Object
Dim buttonCollection As Object
Dim valeur_heure As Object

' Create InternetExplorer Object
Set IE = CreateObject("InternetExplorer.Application")
' You can uncoment Next line To see form results
IE.Visible = True

' Send the form data To URL As POST binary request
IE.navigate ""

' Wait while IE loading...
While IE.Busy

Set objCollection = IE.Document.getElementsByTagName("input")

i = 0
While i < objCollection.Length
    If objCollection(i).Name = "txtUserName" Then
        ' Set text for search
        objCollection(i).Value = "1234"
    End If
    If objCollection(i).Name = "txtPwd" Then
        ' Set text for search
        objCollection(i).Value = "password"
    End If

    If objCollection(i).Type = "submit" And objCollection(i).Name = "btnSubmit" Then ' submit button if found and set
        Set objElement = objCollection(i)
    End If
    i = i + 1
objElement.Click    ' click button to load page

' Wait while IE re-loading...
While IE.Busy

' Show IE
IE.Visible = True
Set Doc = IE.Document

Dim links, link

Dim j As Integer                                                                    'variable to count items
j = 0
Set links = IE.Document.getElementById("dgTime").getElementsByTagName("a")
n = links.Length
While j <= n                                    'loop to go thru all "a" item so it loads next page
    While IE.Busy
    '-------------Do stuff here:  copy field value and paste in excel sheet.  Will post another question for this------------------------
    IE.Document.getElementById("DetailToolbar1_lnkBtnSave").Click              'save
    Do While IE.Busy
        Application.Wait DateAdd("s", 1, Now)                                   'wait
    IE.Document.getElementById("DetailToolbar1_lnkBtnCancel").Click            'close
    Do While IE.Busy
        Application.Wait DateAdd("s", 1, Now)                                   'wait
    Set links = IE.Document.getElementById("dgTime").getElementsByTagName("a")
    j = j + 2
End Sub

Turning off eslint rule for a specific line

The general end of line comment, // eslint-disable-line, does not need anything after it: no need to look up a code to specify what you wish ES Lint to ignore.

If you need to have any syntax ignored for any reason other than a quick debugging, you have problems: why not update your delint config?

I enjoy // eslint-disable-line to allow me to insert console for a quick inspection of a service, without my development environment holding me back because of the breach of protocol. (I generally ban console, and use a logging class - which sometimes builds upon console.)

(Excel) Conditional Formatting based on Adjacent Cell Value

You need to take out the $ signs before the row numbers in the formula....and the row number used in the formula should correspond to the first row of data, so if you are applying this to the ("applies to") range $B$2:$B$5 it must be this formula


by using that "relative" version rather than your "absolute" one Excel (implicitly) adjusts the formula for each row in the range, as if you were copying the formula down

Laravel Rule Validation for Numbers

Laravel min and max validation do not work properly with a numeric rule validation. Instead of numeric, min and max, Laravel provided a rule digits_between.


Android Studio update -Error:Could not run build action using Gradle distribution

You can download the gradle you want from Gradle Service by reading the it ,unpack it where you like and then change your grandle configuration use local not the recommended.

How to include scripts located inside the node_modules folder?

I would use the path npm module and then do something like this:

var path = require('path');
app.use('/scripts', express.static(path.join(__dirname, 'node_modules/bootstrap/dist')));

IMPORTANT: we use path.join to make paths joining using system agnostic way, i.e. on windows and unix we have different path separators (/ and )

Is it possible to use vh minus pixels in a CSS calc()?

It does work indeed. Issue was with my less compiler. It was compiled in to:

.container {
  min-height: calc(-51vh);

Fixed with the following code in less file:

.container {
  min-height: calc(~"100vh - 150px");

Thanks to this link: Less Aggressive Compilation with CSS3 calc

Gradle DSL method not found: 'runProguard'

runProguard has been renamed to minifyEnabled in version 0.14.0 (2014/10/31) or more in Gradle.

To fix this, you need to change runProguard to minifyEnabled in the build.gradle file of your project.

enter image description here

Displaying the Error Messages in Laravel after being Redirected from controller

{!! Form::text('firstname', null !!}

    {{ $errors->first('firstname') }} 

Error inflating class

In the case of Xamarin in VS, you must add

Theme = "@style/MyThemesss"

to youractivity.cs.

I add this and go on.

Jquery Validate custom error message location

What you should use is the errorLabelContainer

jQuery(function($) {_x000D_
  var validator = $('#form').validate({_x000D_
    rules: {_x000D_
      first: {_x000D_
        required: true_x000D_
      second: {_x000D_
        required: true_x000D_
    messages: {},_x000D_
    errorElement : 'div',_x000D_
    errorLabelContainer: '.errorTxt'_x000D_
  border: 1px solid red;_x000D_
  min-height: 20px;_x000D_
<script type="text/javascript" src=""></script>_x000D_
<script type="text/javascript" src=""></script>_x000D_
<script type="text/javascript" src=""></script>_x000D_
<form id="form" method="post" action="">_x000D_
  <input type="text" name="first" />_x000D_
  <input type="text" name="second" />_x000D_
  <div class="errorTxt"></div>_x000D_
  <input type="submit" class="button" value="Submit" />_x000D_

If you want to retain your structure then

jQuery(function($) {_x000D_
  var validator = $('#form').validate({_x000D_
    rules: {_x000D_
      first: {_x000D_
        required: true_x000D_
      second: {_x000D_
        required: true_x000D_
    messages: {},_x000D_
    errorPlacement: function(error, element) {_x000D_
      var placement = $(element).data('error');_x000D_
      if (placement) {_x000D_
      } else {_x000D_
#errNm1 {_x000D_
  border: 1px solid red;_x000D_
#errNm2 {_x000D_
  border: 1px solid green;_x000D_
<script type="text/javascript" src=""></script>_x000D_
<script type="text/javascript" src=""></script>_x000D_
<script type="text/javascript" src=""></script>_x000D_
<form id="form" method="post" action="">_x000D_
  <input type="text" name="first" data-error="#errNm1" />_x000D_
  <input type="text" name="second" data-error="#errNm2" />_x000D_
  <div class="errorTxt">_x000D_
    <span id="errNm2"></span>_x000D_
    <span id="errNm1"></span>_x000D_
  <input type="submit" class="button" value="Submit" />_x000D_

How do I apply a style to all children of an element

Instead of the * selector you can use the :not(selector) with the > selector and set something that definitely wont be a child.

Edit: I thought it would be faster but it turns out I was wrong. Disregard.


.container > :not(marquee){

<div class="container">

Execute curl command within a Python script

You can use below code snippet

import shlex
import subprocess
import json

def call_curl(curl):
    args = shlex.split(curl)
    process = subprocess.Popen(args, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    stdout, stderr = process.communicate()
    return json.loads(stdout.decode('utf-8'))

if __name__ == '__main__':
    curl = '''curl - X
    POST - d
    '{"nw_src": "", "nw_dst": "", "nw_proto": "ICMP", "actions": "ALLOW", "priority": "10"}'
    http: // localhost: 8080 / firewall / rules / 0000000000000001 '''
    output = call_curl(curl)

PowerShell To Set Folder Permissions

$path = "C:\DemoFolder"
$acl = Get-Acl $path
$username = [System.Security.Principal.WindowsIdentity]::GetCurrent().Name
$Attribs = $username, "FullControl", "ContainerInherit,ObjectInherit", "None", "Allow"
$AccessRule = New-Object System.Security.AcessControl.FileSystemAccessRule($Attribs)
$acl | Set-Acl $path
Get-ChildItem -Path "$path" -Recourse -Force | Set-Acl -aclObject $acl -Verbose

Nginx: stat() failed (13: permission denied)

I've just had the same problem on a CentOS 7 box.

Seems I'd hit selinux. Putting selinux into permissive mode (setenforce permissive) has worked round the problem for now. I'll try and get back with a proper fix.

Nginx serves .php files as downloads, instead of executing them

Try this:

  1. Edit /etc/nginx/sites-available/default

  2. Uncomment both listen lines to make nginx listen on port 80 IPv4 and IPv6.

    listen   80; ## listen for ipv4; this line is default and implied
    listen   [::]:80 default_server ipv6only=on; ## listen for ipv6
  3. Leave server_name alone

    # Make site accessible (...)
    server_name localhost;
  4. Add index.php to the index line

    root /usr/share/nginx/www;
    index index.php index.html index.htm;
  5. Uncomment location ~ \.php$ {}

    # pass the PHP scripts to FastCGI server listening on (...)
    location ~ \.php$ {
            try_files $uri =404;
            fastcgi_split_path_info ^(.+\.php)(/.+)$;
            # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
            # With php5-cgi alone:
            # With php5-fpm:
            fastcgi_pass unix:/var/run/php5-fpm.sock;
            fastcgi_index index.php;
            include fastcgi_params;
  6. Edit /etc/php5/fpm/php.ini and make sure cgi.fix_pathinfo is set to 0

  7. Restart nginx and php5-fpm sudo service nginx restart && sudo service php5-fpm restart

I have just started using Linux a week ago, so I really hope to help you on this. I am using nano text editor to edit the files. run apt-get install nano if you don't have it. Google on it to know more.

Font from origin has been blocked from loading by Cross-Origin Resource Sharing policy

Add this rule to your .htaccess

Header add Access-Control-Allow-Origin "*" 

even better, as suggested by @david thomas, you can use a specific domain value, e.g.

Header add Access-Control-Allow-Origin ""

JavaScript Loading Screen while page loads

You can wait until the body is ready:

function onReady(callback) {_x000D_
  var intervalId = window.setInterval(function() {_x000D_
    if (document.getElementsByTagName('body')[0] !== undefined) {_x000D_
  }, 1000);_x000D_
function setVisible(selector, visible) {_x000D_
  document.querySelector(selector).style.display = visible ? 'block' : 'none';_x000D_
onReady(function() {_x000D_
  setVisible('.page', true);_x000D_
  setVisible('#loading', false);_x000D_
body {_x000D_
  background: #FFF url("") top left repeat-x;_x000D_
  font-family: 'Alex Brush', cursive !important;_x000D_
.page    { display: none; padding: 0 0.5em; }_x000D_
.page h1 { font-size: 2em; line-height: 1em; margin-top: 1.1em; font-weight: bold; }_x000D_
.page p  { font-size: 1.5em; line-height: 1.275em; margin-top: 0.15em; }_x000D_
#loading {_x000D_
  display: block;_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: 0;_x000D_
  z-index: 100;_x000D_
  width: 100vw;_x000D_
  height: 100vh;_x000D_
  background-color: rgba(192, 192, 192, 0.5);_x000D_
  background-image: url("");_x000D_
  background-repeat: no-repeat;_x000D_
  background-position: center;_x000D_
<link href="" rel="stylesheet"/>_x000D_
<link href="" rel="stylesheet">_x000D_
<div class="page">_x000D_
  <h1>The standard Lorem Ipsum passage</h1>_x000D_
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure_x000D_
    dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>_x000D_
<div id="loading"></div>

Here is a JSFiddle that demonstrates this technique.

Connection refused to MongoDB errno 111

I follow this tutorial's instructions for installation

How to Install MongoDB on Ubuntu 16.04

I had the same mistake. Finally, I found out that I needed to set the port number

The default port number for the mongo command is 27017

But the default port number in mongo.conf is 29999

Error:(1, 0) Plugin with id '' not found

I was using IntelliJ IDEA 13.1.5 and faced with the same problem after I changed versions of Picasso and Retrofit in dependencies in build.gradle file. I tried use many solutions, but without result. Then I cloned my project from remote git (where I pushed it before changing versions of dependencies) and it worked! After that I just closed current project and imported old project from Gradle file to IntelliJ IDEA again and it worked too! So, I think it was strange bug in intersection of IDEA, Gradle and Android plugin. I hope this information can be useful for IDEA-users or anyone else.

Android Studio : Failure [INSTALL_FAILED_OLDER_SDK]

Just go to build.gradle(Module:App) and change the minSdkVersion to whatever you are using with emulator.


defaultConfig {
        applicationId "com.example.raghu.sample"
        // Change the version in following line
        minSdkVersion 10 // <-- Whatever you are using with Emulator
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"

How to change default format at created_at and updated_at value laravel

You could use

protected $casts = [
    'created_at' => "datetime:Y-m-d\TH:iPZ",

in your model class or any format following this link

Validate date in dd/mm/yyyy format using JQuery Validate

This works fine for me.

$(document).ready(function () {
       $('#btn_move').click( function(){
           var dateformat = /^(0?[1-9]|[12][0-9]|3[01])[\/\-](0?[1-9]|1[012])[\/\-]\d{4}$/;
           var Val_date=$('#txt_date').val();
              var seperator1 = Val_date.split('/');
              var seperator2 = Val_date.split('-');

              if (seperator1.length>1)
                  var splitdate = Val_date.split('/');
              else if (seperator2.length>1)
                  var splitdate = Val_date.split('-');
              var dd = parseInt(splitdate[0]);
              var mm  = parseInt(splitdate[1]);
              var yy = parseInt(splitdate[2]);
              var ListofDays = [31,28,31,30,31,30,31,31,30,31,30,31];
              if (mm==1 || mm>2)
                  if (dd>ListofDays[mm-1])
                      alert('Invalid date format!');
                      return false;
              if (mm==2)
                  var lyear = false;
                  if ( (!(yy % 4) && yy % 100) || !(yy % 400))
                      lyear = true;
                  if ((lyear==false) && (dd>=29))
                      alert('Invalid date format!');
                      return false;
                  if ((lyear==true) && (dd>29))
                      alert('Invalid date format!');
                      return false;
              alert("Invalid date format!");

              return false;

Why cannot change checkbox color whatever I do?

Technically, it is possible to change the color of anything with CSS. As mentioned, you can't change the background-color or color but you can use CSS filters. For example:

input[type="checkbox"] { /* change "blue" browser chrome to yellow */
  filter: invert(100%) hue-rotate(18deg) brightness(1.7);

If you are really looking for design control over checkboxes though, your best bet is to do the "hidden" checkbox and style an adjacent element such as a div.

Apache Proxy: No protocol handler was valid

To clarify for future reference, a2enmod, as is suggested in several answers above, is for Debian/Ubuntu. Red Hat does not use this to enable Apache modules - instead it uses LoadModule statements in httpd.conf.

More here:

The resolution/correct answer is in the comments on the OP:

I think you need mod_ssl and SSLProxyEngine with ProxyPass – Deadooshka May 29 '14 at 11:35

@Deadooshka Yes, this is working. If you post this as an answer, I can accept it – das_j May 29 '14 at 12:04

How Can I Remove “public/index.php” in the URL Generated Laravel?

 RewriteEngine on

 RewriteCond %{REQUEST_FILENAME} !-f
 RewriteCond %{REQUEST_FILENAME} !-d

 RewriteRule ^(.*)$ index.php/$1 [L]

use this in .htaccess and restart the server

phpMyAdmin allow remote users

Just comment all lines in first Directory. Or you can remove these lines, but better to keep in case later you want to add some restrictions, you will uncomment.

#<Directory /usr/share/phpMyAdmin/>
#   <IfModule mod_authz_core.c>
#     # Apache 2.4
#     <RequireAny>
#       Require ip
#       Require ip ::1
#     </RequireAny>
#   </IfModule>
#   <IfModule !mod_authz_core.c>
#     # Apache 2.2
#     Order Deny,Allow
#     Deny from All
#     Allow from
#     Allow from ::1
#   </IfModule>

Laravel: Validation unique on update

From Laravel 5.7, this works great

use Illuminate\Validation\Rule;

Validator::make($data, [
    'email' => [

Forcing A Unique Rule To Ignore A Given ID:


I would be using laravel whereDoesntHave to achieve this.


The condition has length > 1 and only the first element will be used

Like sgibb said it was an if problem, it had nothing to do with | or ||.

Here is another way to solve your problem:

for (i in 1:nrow(trip)) {
  if(trip$Ref.y[i]=='G' & trip$Variant.y[i]=='T'|trip$Ref.y[i]=='C' & trip$Variant.y[i]=='A') {
    trip[i, 'mutType'] <- "G:C to T:A"
  else if(trip$Ref.y[i]=='G' & trip$Variant.y[i]=='C'|trip$Ref.y[i]=='C' & trip$Variant.y[i]=='G') {
    trip[i, 'mutType'] <- "G:C to C:G"
  else if(trip$Ref.y[i]=='G' & trip$Variant.y[i]=='A'|trip$Ref.y[i]=='C' & trip$Variant.y[i]=='T') {
    trip[i, 'mutType'] <- "G:C to A:T"
  else if(trip$Ref.y[i]=='A' & trip$Variant.y[i]=='T'|trip$Ref.y[i]=='T' & trip$Variant.y[i]=='A') {
    trip[i, 'mutType'] <- "A:T to T:A"
  else if(trip$Ref.y[i]=='A' & trip$Variant.y[i]=='G'|trip$Ref.y[i]=='T' & trip$Variant.y[i]=='C') {
    trip[i, 'mutType'] <- "A:T to G:C"
  else if(trip$Ref.y[i]=='A' & trip$Variant.y[i]=='C'|trip$Ref.y[i]=='T' & trip$Variant.y[i]=='G') {
    trip[i, 'mutType'] <- "A:T to C:G"

Forbidden :You don't have permission to access /phpmyadmin on this server

You need to follow the following steps:

Find line that read follows

Require ip

Replace with your workstation IP address:

Require ip

Again find the following line:

Allow from

Replace as follows:

Allow from

Also find deny from all and comment it in the entire file.

Save and close the file.Restart Apache httpd server:

# service httpd restart

Edit: Since this is the selected answer and gets best visibility ... please also make sure that PHP is installed, otherwise you get same Forbidden error.

python object() takes no parameters error

I too got this error. Incidentally, i typed __int__ instead of __init__.

I think, in many mistype cases the IDE i am using (IntelliJ) would have changed the color to the default set for Function definition. But, in my case __int__ being another dunder/magic method, color remained same as the one which IDE displays for __init__ (default Predefined item definition color), which took me some time in spotting the missing i.

INFO: No Spring WebApplicationInitializer types detected on classpath

Make sure that your log4j is configured correctly, there's probably an exception that is being thrown, but you're only seeing half of the picture.

Please see

How do Mockito matchers work?

Just a small addition to Jeff Bowman's excellent answer, as I found this question when searching for a solution to one of my own problems:

If a call to a method matches more than one mock's when trained calls, the order of the when calls is important, and should be from the most wider to the most specific. Starting from one of Jeff's examples:

when(foo.quux(anyInt(), anyInt())).thenReturn(true);
when(foo.quux(anyInt(), eq(5))).thenReturn(false);

is the order that ensures the (probably) desired result:

foo.quux(3 /*any int*/, 8 /*any other int than 5*/) //returns true
foo.quux(2 /*any int*/, 5) //returns false

If you inverse the when calls then the result would always be true.

Apache 2.4 - Request exceeded the limit of 10 internal redirects due to probable configuration error

Solved this by adding following

RewriteCond %{ENV:REDIRECT_STATUS} 200 [OR]
 RewriteCond %{REQUEST_FILENAME} -f [OR]
 RewriteCond %{REQUEST_FILENAME} -d
 RewriteRule ^ - [L]

Error: Configuration with name 'default' not found in Android Studio

If you want to use the same library folder for several projects, you can reference it in gradle to an external location like this:


include 'app', ':volley'
project(':volley').projectDir = new File('../libraries/volley')

in your app build.gradle

dependencies {
    compile project(':volley')

Configuration with name 'default' not found. Android Studio

compile fileTree(dir: 'libraries', include: ['Android-Bootstrap'])

Use above line in your app's gradle file instead of

compile project (':libraries:Android-Bootstrap')

Name [jdbc/mydb] is not bound in this Context

You need a ResourceLink in your META-INF/context.xml file to make the global resource available to the web application.

 <ResourceLink name="jdbc/mydb"
              type="javax.sql.DataSource" />

Conditionally formatting if multiple cells are blank (no numerics throughout spreadsheet )

The steps you took are not appropriate because the cell you want formatted is not the trigger cell (presumably won't normally be blank). In your case you want formatting to apply to one set of cells according to the status of various other cells. I suggest with data layout as shown in the image (and with thanks to @xQbert for a start on a suitable formula) you select ColumnA and:

HOME > Styles - Conditional Formatting, New Rule..., Use a formula to determine which cells to format and Format values where this formula is true::


Format..., select formatting, OK, OK.

SO22487695 example

where I have filled yellow the cells that are triggering the red fill result.

Laravel update model with unique validation rule for attribute

or what you could do in your Form Request is (for Laravel 5.3+)

public function rules()
        return [

            'email' => 'required|email|unique:users,email,'.$this->user, //here user is users/{user} from resource's route url

i've done it in Laravel 5.6 and it worked.

dplyr mutate with conditional values

With dplyr 0.7.2, you can use the very useful case_when function :

 text="V1 V2 V3 V4
 1  1  2  3  5
 2  2  4  4  1
 3  1  4  1  1
 4  4  5  1  3
 5  5  5  5  4")
x$V5 = case_when(x$V1==1 & x$V2!=4 ~ 1,
                 x$V2==4 & x$V3!=1 ~ 2,
                 TRUE ~ 0)

Expressed with dplyr::mutate, it gives:

x = x %>% mutate(
     V5 = case_when(
         V1==1 & V2!=4 ~ 1,
         V2==4 & V3!=1 ~ 2,
         TRUE ~ 0

Please note that NA are not treated specially, as it can be misleading. The function will return NA only when no condition is matched. If you put a line with TRUE ~ ..., like I did in my example, the return value will then never be NA.

Therefore, you have to expressively tell case_when to put NA where it belongs by adding a statement like$V1) |$V3) ~ NA_integer_. Hint: the dplyr::coalesce() function can be really useful here sometimes!

Moreover, please note that NA alone will usually not work, you have to put special NA values : NA_integer_, NA_character_ or NA_real_.

How can I open a .tex file?

I don't know what the .tex extension on your file means. If we are saying that it is any file with any extension you have several methods of reading it.

I have to assume you are using windows because you have mentioned notepad++.

  1. Use notepad++. Right click on the file and choose "edit with notepad++"

  2. Use notepad Change the filename extension to .txt and double click the file.

  3. Use command prompt. Open the folder that your file is in. Hold down shift and right click. (not on the file, but in the folder that the file is in.) Choose "open command window here" from the command prompt type: "type filename.tex"

If these don't work, I would need more detail as to how they are not working. Errors that you may be getting or what you may expect to be in the file might help.

Python circular importing?

I was able to import the module within the function (only) that would require the objects from this module:

def my_func():
    import Foo
    foo_instance = Foo()

Adding a rule in iptables in debian to open a new port

(I presume that you've concluded that it's an iptables problem by dropping the firewall completely (iptables -P INPUT ACCEPT; iptables -P OUTPUT ACCEPT; iptables -F) and confirmed that you can connect to the MySQL server from your Windows box?)

Some previous rule in the INPUT table is probably rejecting or dropping the packet. You can get around that by inserting the new rule at the top, although you might want to review your existing rules to see whether that's sensible:

iptables -I INPUT 1 -p tcp --dport 3306 -j ACCEPT

Note that iptables-save won't save the new rule persistently (i.e. across reboots) - you'll need to figure out something else for that. My usual route is to store the iptables-save output in a file (/etc/network/iptables.rules or similar) and then load then with a pre-up statement in /etc/network/interfaces).

Checkout another branch when there are uncommitted changes on the current branch

In case you don't want this changes to be committed at all do git reset --hard.

Next you can checkout to wanted branch, but remember that uncommitted changes will be lost.

php function mail() isn't working

I think you are not configured properly,

if you are using XAMPP then you can easily send mail from localhost.

for example you can configure C:\xampp\php\php.ini and c:\xampp\sendmail\sendmail.ini for gmail to send mail.

in C:\xampp\php\php.ini find extension=php_openssl.dll and remove the semicolon from the beginning of that line to make SSL working for gmail for localhost.

in php.ini file find [mail function] and change
sendmail_from = [email protected]
sendmail_path = "C:\xampp\sendmail\sendmail.exe -t"

(use the above send mail path only and it will work)

Now Open C:\xampp\sendmail\sendmail.ini. Replace all the existing code in sendmail.ini with following code

[email protected]
[email protected]

Now you have done!! create php file with mail function and send mail from localhost.


First, make sure you PHP installation has SSL support (look for an "openssl" section in the output from phpinfo()).

You can set the following settings in your PHP.ini:


iptables LOG and DROP in one rule

for china GFW:

sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j DROP
sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j LOG --log-prefix "drop rst"

sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j DROP
sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j LOG --log-prefix "drop rst"

sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j DROP
sudo iptables -I INPUT -s -p tcp --tcp-flags RST RST -j LOG --log-prefix "drop rst"

Error: [ng:areq] from angular controller

The error will be seen when your controller could not be found in the application. You need to make sure that you are correct using values in ng-app and ng-controller directives

Jquery validation plugin - TypeError: $(...).validate is not a function

It looks like the JavaScript error your getting is probably being caused by

password: {

As the [4.20] should be [4,20], which i'd guess is throwing off the validation code in additional-methods hence giving the type error's you posted.

Edit: As others have noted in the below comments rangelenght is also misspelled & jquery.validate.js library appears to be missing (assuming its not compiled in to one of your other assets)

numpy matrix vector multiplication

Simplest solution

Use or See the documentation here.

>>> a = np.array([[ 5, 1 ,3], 
                  [ 1, 1 ,1], 
                  [ 1, 2 ,1]])
>>> b = np.array([1, 2, 3])
>>> print
array([16, 6, 8])

This occurs because numpy arrays are not matrices, and the standard operations *, +, -, / work element-wise on arrays. Instead, you could try using numpy.matrix, and * will be treated like matrix multiplication.

Other Solutions

Also know there are other options:

  • As noted below, if using python3.5+ the @ operator works as you'd expect:

    >>> print(a @ b)
    array([16, 6, 8])
  • If you want overkill, you can use numpy.einsum. The documentation will give you a flavor for how it works, but honestly, I didn't fully understand how to use it until reading this answer and just playing around with it on my own.

    >>> np.einsum('ji,i->j', a, b)
    array([16, 6, 8])
  • As of mid 2016 (numpy 1.10.1), you can try the experimental numpy.matmul, which works like with two major exceptions: no scalar multiplication but it works with stacks of matrices.

    >>> np.matmul(a, b)
    array([16, 6, 8])
  • numpy.inner functions the same way as for matrix-vector multiplication but behaves differently for matrix-matrix and tensor multiplication (see Wikipedia regarding the differences between the inner product and dot product in general or see this SO answer regarding numpy's implementations).

    >>> np.inner(a, b)
    array([16, 6, 8])
    # Beware using for matrix-matrix multiplication though!
    >>> b = a.T
    >>>, b)
    array([[35,  9, 10],
           [ 9,  3,  4],
           [10,  4,  6]])
    >>> np.inner(a, b) 
    array([[29, 12, 19],
           [ 7,  4,  5],
           [ 8,  5,  6]])

Rarer options for edge cases

  • If you have tensors (arrays of dimension greater than or equal to one), you can use numpy.tensordot with the optional argument axes=1:

    >>> np.tensordot(a, b, axes=1)
    array([16,  6,  8])
  • Don't use numpy.vdot if you have a matrix of complex numbers, as the matrix will be flattened to a 1D array, then it will try to find the complex conjugate dot product between your flattened matrix and vector (which will fail due to a size mismatch n*m vs n).

Forbidden You don't have permission to access / on this server

Solution is just simple.

If you are trying to access server using your local IP address and you are getting error saying like Forbidden You don't have permission to access / on this server

Just open your httpd.conf file from (in my case C:/wamp/bin/apache/apache2.2.21/conf/httpd.conf)

Search for

<Directory "D:/wamp/www/"> .... ..... </Directory>

Replace Allow from


Allow from all

Save changes and restart your server.

Now you can access your server using your IP address

Htaccess: add/remove trailing slash from URL

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
## hide .html extension
# To externally redirect /dir/foo.html to /dir/foo
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+).html
RewriteRule ^ %1 [R=301,L]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s([^.]+)/\s
RewriteRule ^ %1 [R=301,L]

## To internally redirect /dir/foo to /dir/foo.html
RewriteCond %{REQUEST_FILENAME}.html -f
RewriteRule ^([^\.]+)$ $1.html [L]

<Files ~"^.*\.([Hh][Tt][Aa])">
order allow,deny
deny from all
satisfy all

This removes html code or php if you supplement it. Allows you to add trailing slash and it come up as well as the url without the trailing slash all bypassing the 404 code. Plus a little added security.

Excel VBA Run Time Error '424' object required

The first code line, Option Explicit means (in simple terms) that all of your variables have to be explicitly declared by Dim statements. They can be any type, including object, integer, string, or even a variant.

This line: Dim envFrmwrkPath As Range is declaring the variable envFrmwrkPath of type Range. This means that you can only set it to a range.

This line: Set envFrmwrkPath = ActiveSheet.Range("D6").Value is attempting to set the Range type variable to a specific Value that is in cell D6. This could be a integer or a string for example (depends on what you have in that cell) but it's not a range.

I'm assuming you want the value stored in a variable. Try something like this:

Dim MyVariableName As Integer
MyVariableName = ActiveSheet.Range("D6").Value

This assumes you have a number (like 5) in cell D6. Now your variable will have the value.

For simplicity sake of learning, you can remove or comment out the Option Explicit line and VBA will try to determine the type of variables at run time.

Try this to get through this part of your code

Dim envFrmwrkPath As String
Dim ApplicationName As String
Dim TestIterationName As String

Applying Comic Sans Ms font style

You need to use quote marks.

font-family: "Comic Sans MS", cursive, sans-serif;

Although you really really shouldn't use comic sans. The font has massive stigma attached to it's use; it's not seen as professional at all.

How to conditional format based on multiple specific text in Excel

You can use MATCH for instance.

  1. Select the column from the first cell, for example cell A2 to cell A100 and insert a conditional formatting, using 'New Rule...' and the option to conditional format based on a formula.

  2. In the entry box, put:

    =MATCH(A2, 'Sheet2'!A:A, 0)
  3. Pick the desired formatting (change the font to red or fill the cell background, etc) and click OK.

MATCH takes the value A2 from your data table, looks into 'Sheet2'!A:A and if there's an exact match (that's why there's a 0 at the end), then it'll return the row number.

Note: Conditional formatting based on conditions from other sheets is available only on Excel 2010 onwards. If you're working on an earlier version, you might want to get the list of 'Don't check' in the same sheet.

EDIT: As per new information, you will have to use some reverse matching. Instead of the above formula, try:

=SUM(IFERROR(SEARCH('Sheet2'!$A$1:$A$44, A2),0))

JNI and Gradle in Android Studio

In the module build.gradle, in the task field, I get an error unless I use:

def ndkDir = plugins.getPlugin('').sdkHandler.getNdkFolder()

I see people using

def ndkDir = android.plugin.ndkFolder


def ndkDir = plugins.getPlugin('').sdkHandler.getNdkFolder()

but neither of those worked until I changed it to the plugin I was actually importing.

ERROR 2013 (HY000): Lost connection to MySQL server at 'reading authorization packet', system error: 0

I use several mysql connections (connecting to different sets of databases) in localhost.

This happened to me after I shut my computer down and mysql was not properly shutdown. After starting my machine I was able to successfully connect to multiple db connections except one (I used this a lot before my machine shutdown). As per the instructions in this posts I doubled connect_timeout but I was not able to connect to that one database connection.

I restarted my machine and i can successfully connect now. This will help you unblock yourself but it'd be great if it can be fixed without restarting the machine.

Another concern is: connection_timeout seemed to me delay related problem but I was getting the error immediately in localhost when there is no network in the equation.

Import Google Play Services library in Android Studio

Try this once and make sure you are not getting any error in project Structure saying that "ComGoogleAndroidGmsPlay not added"

Open File > Project Structure and check for below all. If error is shown click on Red bulb marked and click on "Add to dependency".

GMS dependency

This is a bug in Android Studio and fixed for the next release(0.4.3)

How to use particular CSS styles based on screen size / device

Why not use @media-queries? These are designed for that exact purpose. You can also do this with jQuery, but that's a last resort in my book.

var s = document.createElement("script");

//Check if viewport is smaller than 768 pixels
if(window.innerWidth < 768) {
    s.type = "text/javascript";
    s.src = "";
}else { //Else we have a larger screen
    s.type = "text/javascript";
    s.src = "";

    $("head").append(s); //Inject stylesheet

How to open a specific port such as 9090 in Google Compute Engine

You need to:

  1. Go to

  2. Go to my Console

  3. Choose your Project

  4. Choose Networking > VPC network

  5. Choose "Firewalls rules"

  6. Choose "Create Firewall Rule"

  7. To apply the rule to select VM instances, select Targets > "Specified target tags", and enter into "Target tags" the name of the tag. This tag will be used to apply the new firewall rule onto whichever instance you'd like. Then, make sure the instances have the network tag applied.

  8. To allow incoming TCP connections to port 9090, in "Protocols and Ports" enter tcp:9090

  9. Click Create

I hope this helps you.

Update Please refer to docs to customize your rules.

How can I remove Nan from list Python/NumPy

Using your example where...

countries= [nan, 'USA', 'UK', 'France']

Since nan is not equal to nan (nan != nan) and countries[0] = nan, you should observe the following:

countries[0] == countries[0]


countries[1] == countries[1]
countries[2] == countries[2]
countries[3] == countries[3]

Therefore, the following should work:

cleanedList = [x for x in countries if x == x]

SPA best practices for authentication and session management

I would go for the second, the token system.

Did you know about ember-auth or ember-simple-auth? They both use the token based system, like ember-simple-auth states:

A lightweight and unobtrusive library for implementing token based authentication in Ember.js applications.

They have session management, and are easy to plug into existing projects too.

There is also an Ember App Kit example version of ember-simple-auth: Working example of ember-app-kit using ember-simple-auth for OAuth2 authentication.

JQuery Validate input file type

One the elements are added, use the rules method to add the rules

//bug fixed thanks to @Sparky
$('input[name^="fileupload"]').each(function () {
    $(this).rules('add', {
        required: true,
        accept: "image/jpeg, image/pjpeg"

Demo: Fiddle


var filenumber = 1;
$("#AddFile").click(function () { //User clicks button #AddFile
    var $li = $('<li><input type="file" name="FileUpload' + filenumber + '" id="FileUpload' + filenumber + '" required=""/> <a href="#" class="RemoveFileUpload">Remove</a></li>').prependTo("#FileUploader");

    $('#FileUpload' + filenumber).rules('add', {
        required: true,
        accept: "image/jpeg, image/pjpeg"

    return false;

Giving a border to an HTML table row, <tr>

adding border-spacing: 0rem 0.5rem; creates a space for each cell (td, th) items on its bottom while leaving no space between the cells{
        border-collapse: separate;
        border-spacing: 0rem 0.5rem;
    } thead tr.border-row the, tbody tr.border-row td, tbody tr.border-row th{
        border-top: 1px solid #EAEAEA;
        border-bottom: 1px solid #EAEAEA;
        vertical-align: middle;
        white-space: nowrap;
        font-size: 0.875rem;
    } thead tr.border-row th:first-child, tbody tr.border-row td:first-child{
        border-left: 1px solid #EAEAEA;
    } thead tr.border-row th:last-child, tbody tr.border-row td:last-child{
        border-right: 1px solid #EAEAEA;

OPTION (RECOMPILE) is Always Faster; Why?

To add to the excellent list (given by @CodeCowboyOrg) of situations where OPTION(RECOMPILE) can be very helpful,

  1. Table Variables. When you are using table variables, there will not be any pre-built statistics for the table variable, often leading to large differences between estimated and actual rows in the query plan. Using OPTION(RECOMPILE) on queries with table variables allows generation of a query plan that has a much better estimate of the row numbers involved. I had a particularly critical use of a table variable that was unusable, and which I was going to abandon, until I added OPTION(RECOMPILE). The run time went from hours to just a few minutes. That is probably unusual, but in any case, if you are using table variables and working on optimizing, it's well worth seeing whether OPTION(RECOMPILE) makes a difference.

Draw a curve with css

@Navaneeth and @Antfish, no need to transform you can do like this also because in above solution only top border is visible so for inside curve you can use bottom border.

.box {_x000D_
  width: 500px;_x000D_
  height: 100px;_x000D_
  border: solid 5px #000;_x000D_
  border-color: transparent transparent #000 transparent;_x000D_
  border-radius: 0 0 240px 50%/60px;_x000D_
<div class="box"></div>

"An attempt was made to access a socket in a way forbidden by its access permissions" while using SMTP

Windows Firewall was creating this error for me. SMTP was trying to post to GMAIL at port 587. Adding port 587 to the Outbound rule [Outbound HTTP/SMTP/RDP] resolved the issue.

fail to change placeholder color with Bootstrap 3

Bootstrap has 3 lines of CSS, within your bootstrap.css generated file that control the placeholder text color:

.form-control::-moz-placeholder {
  color: #999999;
  opacity: 1;
.form-control:-ms-input-placeholder {
  color: #999999;
.form-control::-webkit-input-placeholder {
  color: #999999;

Now if you add this to your own CSS file it won't override bootstrap's because it is less specific. So assmuning your form inside a then add that to your CSS:

form .form-control::-moz-placeholder {
  color: #fff;
  opacity: 1;
form .form-control:-ms-input-placeholder {
  color: #fff;
form .form-control::-webkit-input-placeholder {
  color: #fff;

Voila that will override bootstrap's CSS.

Bootstrap 3 navbar active li not changing background-color

in my case just removing background-image from nav-bar item solved the problem

.navbar-default .navbar-nav > .active > a:focus {

    background-image: none;

How can I override Bootstrap CSS styles?

To reset the styles defined for legend in bootstrap, you can do following in your css file:

legend {
  all: unset;


The all property in CSS resets all of the selected element's properties, except the direction and unicode-bidi properties that control text direction.

Possible values are: initial, inherit & unset.

Side note: clear property is used in relation with float (

SQLSTATE[42S22]: Column not found: 1054 Unknown column - Laravel

You don't have a field named user_email in the members table ... as for why, I'm not sure as the code "looks" like it should try to join on different fields

Does the Auth::attempt method perform a join of the schema? Run grep -Rl 'class Auth' /path/to/framework and find where the attempt method is and what it does.

Laravel blank white screen

It shows the problem it was the White spaces in App Name of .env file

Android Gradle plugin 0.7.0: "duplicate files during packaging of APK"

Files "LICENSE.txt" and "NOTICE.txt" are case sensitive. So for SPring android library I had to add

android {
    packagingOptions {
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/license.txt'
        exclude 'META-INF/notice.txt'

Permission denied: /var/www/abc/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable?

I had the same issue when I changed the home directory of one use. In my case it was because of selinux. I used the below to fix the issue:

selinuxenabled 0
setenforce 0

CSS property to pad text inside of div

I see a lot of answers here that have you subtracting from the width of the div and/or using box-sizing, but all you need to do is apply the padding the child elements of the div in question. So, for example, if you have some markup like this:

<div id="container">
    <p id="text">Find Agents</p>

All you need to do is apply this CSS:

#text {
    padding: 10px;

Here is a fiddle showing the difference:

Or, better yet, if you have multiple elements and don't feel like giving them all the same class, you can do something like this:

.container * {
    padding: 5px 10px;

Which will select all of the child elements and assign them the padding you want. Here is a fiddle of that in action:

nginx error:"location" directive is not allowed here in /etc/nginx/nginx.conf:76

Since your server already includes the sites-enabled folder ( notice the include /etc/nginx/sites-enabled/* line ), then you better use that.

  1. Create a file inside /etc/nginx/sites-available and call it whatever you want, I'll call it django since it's a djanog server

    sudo touch /etc/nginx/sites-available/django
  2. Then create a symlink that points to it

    sudo ln -s /etc/nginx/sites-available/django /etc/nginx/sites-enabled
  3. Then edit that file with whatever file editor you use, vim or nano or whatever and create the server inside it

    server {
        # hostname or ip or multiple separated by spaces
        server_name localhost; #change to your setting
        location / {
            root /home/techcee/scrapbook/local/lib/python2.7/site-packages/django/__init__.pyc/;
  4. Restart or reload nginx settings

    sudo service nginx reload

Note I believe that your configuration like this probably won't work yet because you need to pass it to a fastcgi server or something, but at least this is how you could create a valid server

How to getText on an input in protractor

below code works for me, for getting text from input

        console.log("--------" + text);

How to extract the decision rules from scikit-learn decision-tree?

I created my own function to extract the rules from the decision trees created by sklearn:

import pandas as pd
import numpy as np
from sklearn.tree import DecisionTreeClassifier

# dummy data:
df = pd.DataFrame({'col1':[0,1,2,3],'col2':[3,4,5,6],'dv':[0,1,0,1]})

# create decision tree
dt = DecisionTreeClassifier(max_depth=5, min_samples_leaf=1)[:,:2], df.dv)

This function first starts with the nodes (identified by -1 in the child arrays) and then recursively finds the parents. I call this a node's 'lineage'. Along the way, I grab the values I need to create if/then/else SAS logic:

def get_lineage(tree, feature_names):
     left      = tree.tree_.children_left
     right     = tree.tree_.children_right
     threshold = tree.tree_.threshold
     features  = [feature_names[i] for i in tree.tree_.feature]

     # get ids of child nodes
     idx = np.argwhere(left == -1)[:,0]     

     def recurse(left, right, child, lineage=None):          
          if lineage is None:
               lineage = [child]
          if child in left:
               parent = np.where(left == child)[0].item()
               split = 'l'
               parent = np.where(right == child)[0].item()
               split = 'r'

          lineage.append((parent, split, threshold[parent], features[parent]))

          if parent == 0:
               return lineage
               return recurse(left, right, parent, lineage)

     for child in idx:
          for node in recurse(left, right, child):
               print node

The sets of tuples below contain everything I need to create SAS if/then/else statements. I do not like using do blocks in SAS which is why I create logic describing a node's entire path. The single integer after the tuples is the ID of the terminal node in a path. All of the preceding tuples combine to create that node.

In [1]: get_lineage(dt, df.columns)
(0, 'l', 0.5, 'col1')
(0, 'r', 0.5, 'col1')
(2, 'l', 4.5, 'col2')
(0, 'r', 0.5, 'col1')
(2, 'r', 4.5, 'col2')
(4, 'l', 2.5, 'col1')
(0, 'r', 0.5, 'col1')
(2, 'r', 4.5, 'col2')
(4, 'r', 2.5, 'col1')

GraphViz output of example tree

Multiple files upload in Codeigniter

private function upload_files($path, $title, $files)
    $config = array(
        'upload_path'   => $path,
        'allowed_types' => 'jpg|gif|png',
        'overwrite'     => 1,

    $this->load->library('upload', $config);

    $images = array();

    foreach ($files['name'] as $key => $image) {
        $_FILES['images[]']['name']= $files['name'][$key];
        $_FILES['images[]']['type']= $files['type'][$key];
        $_FILES['images[]']['tmp_name']= $files['tmp_name'][$key];
        $_FILES['images[]']['error']= $files['error'][$key];
        $_FILES['images[]']['size']= $files['size'][$key];

        $fileName = $title .'_'. $image;

        $images[] = $fileName;

        $config['file_name'] = $fileName;


        if ($this->upload->do_upload('images[]')) {
        } else {
            return false;
    return true;

When to use Task.Delay, when to use Thread.Sleep?

if the current thread is killed and you use Thread.Sleep and it is executing then you might get a ThreadAbortException. With Task.Delay you can always provide a cancellation token and gracefully kill it. Thats one reason I would choose Task.Delay. see

I also agree efficiency is not paramount in this case.

Print page numbers on pages when printing html

   **@page {
            margin-top:21% !important; 
            content: element(header);


            @bottom-left {
            content: element(footer
 div.header {

            position: running(header);

            div.footer {

            position: running(footer);
            border-bottom: 2px solid black;

           .pagenumber:before {
            content: counter(page);
            .pagecount:before {
            content: counter(pages);
 <div class="footer" style="font-size:12pt; font-family: Arial; font-family: Arial;">
                <span>Page <span class="pagenumber"/> of <span class="pagecount"/></span>
            </div >**

jquery to validate phone number

Your code:

rules: {
    phoneNumber: {
        matches: "[0-9]+",  // <-- no such method called "matches"!

There is no such callback function, option, method, or rule called matches anywhere within the jQuery Validate plugin. (EDIT: OP failed to mention that matches is his custom method.)

However, within the additional-methods.js file, there are several phone number validation methods you can use. The one called phoneUS should satisfy your pattern. Since the rule already validates the length, minlength and maxlength are redundantly unnecessary. It's also much more comprehensive in that area codes and prefixes can not start with a 1.

rules: {
    phoneNumber: {
        phoneUS: true


If, for whatever reason, you just need the regex for use in another method, you can take it from here...

jQuery.validator.addMethod("phoneUS", function(phone_number, element) {
    phone_number = phone_number.replace(/\s+/g, "");
    return this.optional(element) || phone_number.length > 9 && 
}, "Please specify a valid phone number");

Compile throws a "User-defined type not defined" error but does not go to the offending line of code

Late Binding

This error can occur due to a missing reference. For example when changing from early binding to late binding, by eliminating the reference, some code may remain that references data types specific the the dropped reference.

Try including the reference to see if the problem disappears.

Maybe the error is not a compiler error but a linker error, so the specific line is unknown. Shame on Microsoft!

Apply .gitignore on an existing repository already tracking large number of files

If you added your .gitignore too late, git will continue to track already commited files regardless. To fix this, you can always remove all cached instances of the unwanted files.

First, to check what files are you actually tracking, you can run:

git ls-tree --name-only --full-tree -r HEAD

Let say that you found unwanted files in a directory like cache/ so, it's safer to target that directory instead of all of your files.

So instead of:

git rm -r --cached .

It's safer to target the unwanted file or directory:

git rm -r --cached cache/

Then proceed to add all changes,

git add .

and commit...

git commit -m ".gitignore is now working"


How to Clone Objects

a and b are just two references to the same Person object. They both essentially hold the address of the Person.

There is a ICloneable interface, though relatively few classes support it. With this, you would write:

Person b = a.Clone();

Then, b would be an entirely separate Person.

You could also implement a copy constructor:

public Person(Person src)
  // ... 

There is no built-in way to copy all the fields. You can do it through reflection, but there would be a performance penalty.

Remove menubar from Electron app

setMenu(null); is the best answer, autohidemenu will display on the start of the application

    function createWindow(){
        const win = new BrowserWindow({
            width: 1500,
            height: 800,
                nodeIntergration: true

jQuery Validation using the class instead of the name value

If you want add Custom method you can do it

(in this case, at least one checkbox selected)

<input class="checkBox" type="checkbox" id="i0000zxthy" name="i0000zxthy"  value="1" onclick="test($(this))"/>

in Javascript

var tags = 0;

$(document).ready(function() {   

    $.validator.addMethod('arrayminimo', function(value) {
        return tags > 0
    }, 'Selezionare almeno un Opzione');

    $.validator.addClassRules('check_secondario', {
        arrayminimo: true,



function validaFormRichiesta() {

function test(n) {
    if (n.prop("checked")) {
    } else {

Upgrading Node.js to latest version

All platforms (Windows, Mac & Linux)

Just go to and download the latest installer. It couldn't be any simpler honestly, and without involvement of any third-party stuff. It only takes a minute and does not require you to restart anything or clean out caches, etc.

I've done it via npm a few times before and have run into a few issues. Like for example with the n-package not using the latest stable release.

Could not connect to SMTP host:, port: 465, response: -1

You need to tell it that you are using SSL:

props.put("mail.smtp.socketFactory.class", "");

In case you miss anything, here is working code:

String  d_email = "[email protected]",
            d_uname = "Name",
            d_password = "urpassword",
            d_host = "",
            d_port  = "465",
            m_to = "[email protected]",
            m_subject = "Indoors Readable File: " + params[0].getName(),
            m_text = "This message is from Indoor Positioning App. Required file(s) are attached.";
    Properties props = new Properties();
    props.put("mail.smtp.user", d_email);
    props.put("", d_host);
    props.put("mail.smtp.port", d_port);
    props.put("mail.smtp.debug", "true");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.socketFactory.port", d_port);
    props.put("mail.smtp.socketFactory.class", "");
    props.put("mail.smtp.socketFactory.fallback", "false");

    SMTPAuthenticator auth = new SMTPAuthenticator();
    Session session = Session.getInstance(props, auth);

    MimeMessage msg = new MimeMessage(session);
    try {
        msg.setFrom(new InternetAddress(d_email));
        msg.addRecipient(Message.RecipientType.TO, new InternetAddress(m_to));

Transport transport = session.getTransport("smtps");
            transport.connect(d_host, Integer.valueOf(d_port), d_uname, d_password);
            transport.sendMessage(msg, msg.getAllRecipients());

        } catch (AddressException e) {
            return false;
        } catch (MessagingException e) {
            return false;

How to remove the first and the last character of a string

use .replace(/.*\/(\S+)\//img,"$1")

"/installers/services/".replace(/.*\/(\S+)\//img,"$1"); //--> services

"/services/".replace(/.*\/(\S+)\//img,"$1"); //--> services

sweet-alert display HTML code in text

I just applied the patch above and it starts working.

diff --git a/sweet-alert.js b/sweet-alert.js_x000D_
index ab6e1f1..d7eafaa 100755_x000D_
--- a/sweet-alert.js_x000D_
+++ b/sweet-alert.js_x000D_
@@ -200,7 +200,8 @@_x000D_
       confirmButtonColor: '#AEDEF4',_x000D_
       cancelButtonText: 'Cancel',_x000D_
       imageUrl: null,_x000D_
-      imageSize: null_x000D_
+      imageSize: null,_x000D_
+      html: false_x000D_
     if (arguments[0] === undefined) {_x000D_
@@ -224,6 +225,7 @@_x000D_
           return false;_x000D_
+        params.html               = arguments[0].html;_x000D_
         params.title              = arguments[0].title;_x000D_
         params.text               = arguments[0].text || params.text;_x000D_
         params.type               = arguments[0].type || params.type;_x000D_
@@ -477,11 +479,18 @@_x000D_
         $cancelBtn = modal.querySelector('button.cancel'),_x000D_
         $confirmBtn = modal.querySelector('button.confirm');_x000D_
+      console.log(params.html);_x000D_
     // Title_x000D_
-    $title.innerHTML = escapeHtml(params.title).split("\n").join("<br>");_x000D_
+    if(params.html)_x000D_
+      $title.innerHTML = params.title.split("\n").join("<br>");_x000D_
+    else_x000D_
+      $title.innerHTML = escapeHtml(params.title).split("\n").join("<br>");_x000D_
     // Text_x000D_
-    $text.innerHTML = escapeHtml(params.text || '').split("\n").join("<br>");_x000D_
+    if(params.html)_x000D_
+      $text.innerHTML = params.text.split("\n").join("<br>");_x000D_
+    else_x000D_
+      $text.innerHTML = escapeHtml(params.text || '').split("\n").join("<br>");_x000D_
     if (params.text) {_x000D_

Hibernate Delete query

The reason is that for deleting an object, Hibernate requires that the object is in persistent state. Thus, Hibernate first fetches the object (SELECT) and then removes it (DELETE).

Why Hibernate needs to fetch the object first? The reason is that Hibernate interceptors might be enabled (, and the object must be passed through these interceptors to complete its lifecycle. If rows are delete directly in the database, the interceptor won't run.

On the other hand, it's possible to delete entities in one single SQL DELETE statement using bulk operations:

Query q = session.createQuery("delete Entity where id = X");

Why not use Double or Float to represent currency?

This is not a matter of accuracy, nor is it a matter of precision. It is a matter of meeting the expectations of humans who use base 10 for calculations instead of base 2. For example, using doubles for financial calculations does not produce answers that are "wrong" in a mathematical sense, but it can produce answers that are not what is expected in a financial sense.

Even if you round off your results at the last minute before output, you can still occasionally get a result using doubles that does not match expectations.

Using a calculator, or calculating results by hand, 1.40 * 165 = 231 exactly. However, internally using doubles, on my compiler / operating system environment, it is stored as a binary number close to 230.99999... so if you truncate the number, you get 230 instead of 231. You may reason that rounding instead of truncating would have given the desired result of 231. That is true, but rounding always involves truncation. Whatever rounding technique you use, there are still boundary conditions like this one that will round down when you expect it to round up. They are rare enough that they often will not be found through casual testing or observation. You may have to write some code to search for examples that illustrate outcomes that do not behave as expected.

Assume you want to round something to the nearest penny. So you take your final result, multiply by 100, add 0.5, truncate, then divide the result by 100 to get back to pennies. If the internal number you stored was 3.46499999.... instead of 3.465, you are going to get 3.46 instead 3.47 when you round the number to the nearest penny. But your base 10 calculations may have indicated that the answer should be 3.465 exactly, which clearly should round up to 3.47, not down to 3.46. These kinds of things happen occasionally in real life when you use doubles for financial calculations. It is rare, so it often goes unnoticed as an issue, but it happens.

If you use base 10 for your internal calculations instead of doubles, the answers are always exactly what is expected by humans, assuming no other bugs in your code.

Get the data received in a Flask request

To get request.form as a normal dictionary , use request.form.to_dict(flat=False).

To return JSON data for an API, pass it to jsonify.

This example returns form data as JSON data.

@app.route('/form_to_json', methods=['POST'])
def form_to_json():
    data = request.form.to_dict(flat=False)
    return jsonify(data)

Here's an example of POST form data with curl, returning as JSON:

$ curl -d "name=ivanleoncz&role=Software Developer"
  "name": "ivanleoncz", 
  "role": "Software Developer"

COLLATION 'utf8_general_ci' is not valid for CHARACTER SET 'latin1'

Firstly run this query


You have character_set_server='latin1'

for eg if CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci replace it to CHARSET=latin1 and remove the collate

You are good to go

How to load a UIView using a nib file created with Interface Builder

Thank you all. I did find a way to do what I wanted.

  1. Create your UIView with the IBOutlets you need.
  2. Create the xib in IB, design it to you liking and link it like this: The File's Owner is of class UIViewController (No custom subclass, but the "real" one). The File Owner's view is connected to the main view and its class is declared as the one from step 1).
  3. Connect your controls with the IBOutlets.
  4. The DynamicViewController can run its logic to decide what view/xib to load. Once its made the decission, in the loadView method put something like this:

    NSArray* nibViews = [[NSBundle mainBundle] loadNibNamed:@"QPickOneView"
    QPickOneView* myView = [ nibViews objectAtIndex: 1];
    myView.question = question;

That's it!

The main bundle's loadNibNamed method will take care of initializing the view and creating the connections.

Now the ViewController can display a view or another depending on the data in memory, and the "parent" screen doesn't need to bother with this logic.

How to rename a file using svn?

This message will appear if you are using a case-insensitive file system (e.g. on a Mac) and you're trying to capitalize the name (or another change of case). In which case you need to rename to a third, dummy, name:

svn mv file-name file-name_
svn mv file-name_ FILE_Name
svn commit

How to convert string to char array in C++?

You could use strcpy(), like so:

strcpy(tab2, tmp.c_str());

Watch out for buffer overflow.

mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead


/* Database config */

$db_host        = 'localhost';
$db_user        = '~';
$db_pass        = '~';
$db_database    = 'banners'; 

/* End config */

$mysqli = new mysqli($db_host, $db_user, $db_pass, $db_database);
/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());


How can I send an HTTP POST request to a server from Excel using VBA?

You can use ServerXMLHTTP in a VBA project by adding a reference to MSXML.

  1. Open the VBA Editor (usually by editing a Macro)
  2. Go to the list of Available References
  3. Check Microsoft XML
  4. Click OK.

(from Referencing MSXML within VBA Projects)

The ServerXMLHTTP MSDN documentation has full details about all the properties and methods of ServerXMLHTTP.

In short though, it works basically like this:

  1. Call open method to connect to the remote server
  2. Call send to send the request.
  3. Read the response via responseXML, responseText, responseStream or responseBody

How do I force Postgres to use a particular index?

Check your random_page_cost

This problem typically happens when the estimated cost of an index scan is too high and doesn't correctly reflect reality. You may need to lower the random_page_cost configuration parameter to fix this. From the Postgres documentation:

Reducing this value [...] will cause the system to prefer index scans; raising it will make index scans look relatively more expensive.

You can do a quick test whether this will actually make Postgres use the index:

EXPLAIN <query>;              # Uses sequential scan
SET random_page_cost = 1;
EXPLAIN <query>;              # May use index scan now

You can restore the default value with SET random_page_cost = DEFAULT; again.


Index scans require non-sequential disk page fetches. Postgres uses random_page_cost to estimate the cost of such non-sequential fetches in relation to sequential fetches. The default value is 4.0, thus assuming an average cost factor of 4 compared to sequential fetches (taking caching effects into account).

The problem however is that this default value is unsuitable in the following important real-life scenarios:

1) Solid-state drives

As per the documentation:

Storage that has a low random read cost relative to sequential, e.g. solid-state drives, might be better modeled with a lower value for random_page_cost, e.g., 1.1.

This slide from a speak at PostgresConf 2018 also says that random_page_cost should be set to something between 1.0 and 2.0 for solid-state drives.

2) Cached data

If the required index data is already cached in RAM, an index scan will always be significantly faster than a sequential scan. The documentation says:

If your data is likely to be completely in cache, [...] decreasing random_page_cost can be appropriate.

The problem is that you of course can't easily know whether the relevant data is already cached. However, if a specific index is frequently used, and if the system has sufficient RAM, then data is likely to be cached eventually, and random_page_cost should be set to a lower value. You'll have to experiment with different values and see what works for you.

You might also want to use the pg_prewarm extension for explicit data caching.

Getting Django admin url for an object

I solved this by changing the expression to:

reverse( 'django-admin', args=["%s/%s/%s/" % (app_label, model_name, object_id)] )

This requires/assumes that the root url conf has a name for the "admin" url handler, mainly that name is "django-admin",

i.e. in the root url conf:

url(r'^admin/(.*)',, name='django-admin'),

It seems to be working, but I'm not sure of its cleanness.

How can I tell jaxb / Maven to generate multiple schema packages?

This is fixed in version 1.6 of the plugin.


Quick note though, I noticed that the first iteration output was being deleted. I fixed it by adding the following to each of the executions.


Here is my full working example with each iteration outputting correctly. BTW I had to do this due to a duplicate namespace problem with the xsd's I was given. This seems to resolve my problem.

                        <!-- <schemaFiles>getOrderStatusResponse.xsd,quoteShippingRequest.xsd,quoteShippingResponse.xsd,submitOrderRequest.xsd,submitOrderResponse.xsd</schemaFiles> -->
                        <!-- <schemaFiles>getOrderStatusResponse.xsd,quoteShippingRequest.xsd,quoteShippingResponse.xsd,submitOrderRequest.xsd,submitOrderResponse.xsd</schemaFiles> -->


How to make remote REST call inside Node.js? any CURL?

I use node-fetch because it uses the familiar (if you are a web developer) fetch() API. fetch() is the new way to make arbitrary HTTP requests from the browser.

Yes I know this is a node js question, but don't we want to reduce the number of API's developers have to memorize and understand, and improve re-useability of our javascript code? Fetch is a standard so how about we converge on that?

The other nice thing about fetch() is that it returns a javascript Promise, so you can write async code like this:

let fetch = require('node-fetch');

fetch('http://localhost', {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: '{}'
}).then(response => {
  return response.json();
}).catch(err => {console.log(err);});

Fetch supersedes XMLHTTPRequest. Here's some more info.

JQuery/Javascript: check if var exists

You can use typeof:

if (typeof pagetype === 'undefined') {
    // pagetype doesn't exist

How to get a DOM Element from a JQuery Selector

I needed to get the element as a string.


Which will give you something like:

<input type="text" id="bob" value="hello world" /> a string rather than a DOM element.

Unable to resolve host "<URL here>" No address associated with host name

I had the same issue. My virtual device was showing a crossed-out WiFi icon at the top bar of the device. I rebooted the virtual device and everything was back to normal.

Set the table column width constant regardless of the amount of text in its cells?

I found KAsun's answer works better using vw instead of px like so:

<td><div style="width: 10vw" >...............</div></td>

This was the only styling I needed to adjust the column width

SQL Bulk Insert with FIRSTROW parameter skips the following line

I don't think you can skip rows in a different format with BULK INSERT/BCP.

When I run this:


BULK INSERT so1029384
FROM 'C:\Data\test\so1029384.txt'

SELECT * FROM so1029384

I get:

col1                                               col2                                               col3
-------------------------------------------------- -------------------------------------------------- --------------------------------------------------
0000001234               SSNV                                               00013893-03JUN09
0000005678                                         ABCD                                               00013893-03JUN09
0000009112                                         0000                                               00013893-03JUN09
0000009112                                         0000                                               00013893-03JUN09

It looks like it requires the '|' even in the header data, because it reads up to that into the first column - swallowing up a newline into the first column. Obviously if you include a field terminator parameter, it expects that every row MUST have one.

You could strip the row with a pre-processing step. Another possibility is to select only complete rows, then process them (exluding the header). Or use a tool which can handle this, like SSIS.

How can I create numbered map markers in Google Maps V3?

How about this? (year 2015)

1) Get a custom marker image.

var imageObj = new Image();
    imageObj.src = "/markers/blank_pin.png"; 

2) Create a canvas in RAM and draw this image on it

imageObj.onload = function(){
    var canvas = document.createElement('canvas');
    var context = canvas.getContext("2d");
    context.drawImage(imageObj, 0, 0);

3) Write anything above it

context.font = "40px Arial";
context.fillText("54", 17, 55);

4) Get raw data from canvas and provide it to Google API instead of URL

var image = {
    url: canvas.toDataURL(),
 new google.maps.Marker({
    position: position,
    map: map,
    icon: image

enter image description here

Full code:

function addComplexMarker(map, position, label, callback){
    var canvas = document.createElement('canvas');
    var context = canvas.getContext("2d");
    var imageObj = new Image();
    imageObj.src = "/markers/blank_pin.png";
    imageObj.onload = function(){
        context.drawImage(imageObj, 0, 0);

        //Adjustable parameters
        context.font = "40px Arial";
        context.fillText(label, 17, 55);

        var image = {
            url: canvas.toDataURL(),
            size: new google.maps.Size(80, 104),
            origin: new google.maps.Point(0,0),
            anchor: new google.maps.Point(40, 104)
        // the clickable region of the icon.
        var shape = {
            coords: [1, 1, 1, 104, 80, 104, 80 , 1],
            type: 'poly'
        var marker = new google.maps.Marker({
            position: position,
            map: map,
            labelAnchor: new google.maps.Point(3, 30),
            icon: image,
            shape: shape,
            zIndex: 9999
        callback && callback(marker)

How to find the default JMX port number?

Now I need to connect that application from my local computer, but I don't know the JMX port number of the remote computer. Where can I find it? Or, must I restart that application with some VM parameters to specify the port number?

By default JMX does not publish on a port unless you specify the arguments from this page: How to activate JMX... # no longer required for JDK6 # careful with security implications # careful with security implications

If you are running you should be able to access any of those system properties to see if they have been set:

if (System.getProperty("") == null) {
    System.out.println("JMX remote is disabled");
} else [
    String portString = System.getProperty("");
    if (portString != null) {
        System.out.println("JMX running on port "
            + Integer.parseInt(portString));

Depending on how the server is connected, you might also have to specify the following parameter. As part of the initial JMX connection, jconsole connects up to the RMI port to determine which port the JMX server is running on. When you initially start up a JMX enabled application, it looks its own hostname to determine what address to return in that initial RMI transaction. If your hostname is not in /etc/hosts or if it is set to an incorrect interface address then you can override it with the following:

-Djava.rmi.server.hostname=<IP address>

As an aside, my SimpleJMX package allows you to define both the JMX server and the RMI port or set them both to the same port. The above port defined with is actually the RMI port. This tells the client what port the JMX server is running on.

System not declared in scope?

You need to add:

 #include <cstdlib>

in order for the compiler to see the prototype for system().

How do I create a new Git branch from an old commit?


This will create a new branch called 'NEW_BRANCH_NAME' and check it out.

("check out" means "to switch to the branch")


This just creates the new branch without checking it out.

in the comments many people seem to prefer doing this in two steps. here's how to do so in two steps:

git checkout COMMIT_ID
# you are now in the "detached head" state
git checkout -b NEW_BRANCH_NAME

What is the preferred Bash shebang?

/bin/sh is usually a link to the system's default shell, which is often bash but on, e.g., Debian systems is the lighter weight dash. Either way, the original Bourne shell is sh, so if your script uses some bash (2nd generation, "Bourne Again sh") specific features ([[ ]] tests, arrays, various sugary things, etc.), then you should be more specific and use the later. This way, on systems where bash is not installed, your script won't run. I understand there may be an exciting trilogy of films about this evolution...but that could be hearsay.

Also note that when evoked as sh, bash to some extent behaves as POSIX standard sh (see also the GNU docs about this).

How to delete a folder in C++?

The directory must be empty and your program must have permissions to delete it

but the function called rmdir will do it

rmdir("C:/Documents and Settings/user/Desktop/itsme") 

Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation

Defining insertable=false, updatable=false is useful when you need to map a field more than once in an entity, typically:

This is IMO not a semantical thing, but definitely a technical one.

Converting HTML to plain text in PHP for e-mail

You can test this function

function html2text($Document) {
    $Rules = array ('@<script[^>]*?>.*?</script>@si',
    $Replace = array ('',
                      ' ',
  return preg_replace($Rules, $Replace, $Document);

How to get min, seconds and milliseconds from in python?

Another similar solution:

>>> "%s:%s.%s" % (a.hour, a.minute, a.microsecond)

Yes, I know I didn't get the string formatting perfect.

moment.js, how to get day of week number

Define "doesn't work".

const date = moment("2015-07-02"); // Thursday Feb 2015_x000D_
const dow =;_x000D_
<script src=""></script>

This prints "4", as expected.

how to fix java.lang.IndexOutOfBoundsException

You are trying to access the first element lstpp.get(0) of an empty array. Just add an element to your array and check for !lstpp.isEmpty() before accessing an element

File path to resource in our war/WEB-INF folder?

There's a couple ways of doing this. As long as the WAR file is expanded (a set of files instead of one .war file), you can use this API:

ServletContext context = getContext();
String fullPath = context.getRealPath("/WEB-INF/test/foo.txt");

That will get you the full system path to the resource you are looking for. However, that won't work if the Servlet Container never expands the WAR file (like Tomcat). What will work is using the ServletContext's getResource methods.

ServletContext context = getContext();
URL resourceUrl = context.getResource("/WEB-INF/test/foo.txt");

or alternatively if you just want the input stream:

InputStream resourceContent = context.getResourceAsStream("/WEB-INF/test/foo.txt");

The latter approach will work no matter what Servlet Container you use and where the application is installed. The former approach will only work if the WAR file is unzipped before deployment.

EDIT: The getContext() method is obviously something you would have to implement. JSP pages make it available as the context field. In a servlet you get it from your ServletConfig which is passed into the servlet's init() method. If you store it at that time, you can get your ServletContext any time you want after that.

How can I make my match non greedy in vim?


Vim's regexp processing is not too brilliant. I've found that the regexp syntax for sed is about the right match for vim's capabilities.

I usually set the search highlighting on (:set hlsearch) and then play with the regexp after entering a slash to enter search mode.

Edit: Mark, that trick to minimise greedy matching is also covered in Dale Dougherty's excellent book "Sed & Awk" (sanitised Amazon link).

Chapter Three "Understanding Regular Expression Syntax" is an excellent intro to the more primitive regexp capabilities involved with sed and awk. Only a short read and highly recommended.



Changing date format in R

This is really easy using package lubridate. All you have to do is tell R what format your date is already in. It then converts it into the standard format

nzd$date <- dmy(nzd$date)

that's it.

Flutter position stack widget in center

Have a look at this solution I came up with

Positioned( child: SizedBox( child: CircularProgressIndicator(), width: 50, height: 50,), left: MediaQuery.of(context).size.width / 2 - 25);

Are multi-line strings allowed in JSON?

This is a really old question, but I came across this on a search and I think I know the source of your problem.

JSON does not allow "real" newlines in its data; it can only have escaped newlines. See the answer from @YOU. According to the question, it looks like you attempted to escape line breaks in Python two ways: by using the line continuation character ("\") or by using "\n" as an escape.

But keep in mind: if you are using a string in python, special escaped characters ("\t", "\n") are translated into REAL control characters! The "\n" will be replaced with the ASCII control character representing a newline character, which is precisely the character that is illegal in JSON. (As for the line continuation character, it simply takes the newline out.)

So what you need to do is to prevent Python from escaping characters. You can do this by using a raw string (put r in front of the string, as in r"abc\ndef", or by including an extra slash in front of the newline ("abc\\ndef").

Both of the above will, instead of replacing "\n" with the real newline ASCII control character, will leave "\n" as two literal characters, which then JSON can interpret as a newline escape.

How to escape strings in SQL Server using PHP?

For the conversion to get the hexadecimal values in SQL back into ASCII, here is the solution I got on this (using the function from user chaos to encode into hexadecimal)

function hexEncode($data) {
        return $data;
    $unpacked = unpack('H*hex', $data);
    return '0x' . $unpacked['hex'];

function hexDecode($hex) {
    $str = '';
    for ($i=0; $i<strlen($hex); $i += 2)
        $str .= chr(hexdec(substr($hex, $i, 2)));
    return $str;

$stringHex = hexEncode('Test String');
$stringAscii = hexDecode($stringHex);

Javascript Equivalent to PHP Explode()

var str = "helloword~this~is~me";
var exploded = str.splice(~);

the exploded variable will return array and you can access elements of the array be accessing it true exploded[nth] where nth is the index of the value you want to get

Find UNC path of a network drive?

This question has been answered already, but since there is a more convenient way to get the UNC path and some more I recommend using Path Copy, which is free and you can practically get any path you want with one click:

Here is a screenshot demonstrating how it works. The latest version has more options and definitely UNC Path too:

enter image description here

Top 1 with a left join

Because the TOP 1 from the ordered sub-query does not have profile_id = 'u162231993' Remove where = 'u162231993' and see results then.

Run the sub-query separately to understand what's going on.

Python 3 - Encode/Decode vs Bytes/Str

To add to add to the previous answer, there is even a fourth way that can be used

import codecs
encoded4 = codecs.encode(original, 'utf-8')

JavaScript/jQuery - "$ is not defined- $function()" error

Im using Asp.Net Core 2.2 with MVC and Razor cshtml My JQuery is referenced in a layout page I needed to add the following to my view.cshtml:

@section Scripts {

Assignment makes pointer from integer without cast

You are returning char, and not char*, which is the pointer to the first character of an array.

If you want to return a new character array instead of doing in-place modification, you can ask for an already allocated pointer (char*) as parameter or an uninitialized pointer. In this last case you must allocate the proper number of characters for new string and remember that in C parameters as passed by value ALWAYS, so you must use char** as parameter in the case of array allocated internally by function. Of course, the caller must free that pointer later.

How do I use Docker environment variable in ENTRYPOINT array?

After much pain, and great assistance from @vitr et al above, i decided to try

  • standard bash substitution
  • shell form of ENTRYPOINT (great tip from above)

and that worked.


ENTRYPOINT java -cp "app:app/lib/*" hello.Application --server.port=${LISTEN_PORT:-80}


docker run --rm -p 8080:8080 -d --env LISTEN_PORT=8080 my-image


docker run --rm -p 8080:80 -d my-image

both set the port correctly in my container



What is the color code for transparency in CSS?

Or you could just put

background-color: rgba(0,0,0,0.0);

That should solve your problem.

Why am I getting the message, "fatal: This operation must be run in a work tree?"

Also, you are probably inside the .git subfolder, move up one folder to your project root.

How to implement an android:background that doesn't stretch?

You can use a FrameLayout with an ImageView as the first child, then your normal layout as the second child:

<?xml version="1.0" encoding="utf-8"?>





How to convert all tables in database to one collation?

Taking the answer from @Petr Stastny a step further by adding a password variable. I'd prefer if it actually took it in like a regular password rather than as an argument, but it's working for what I needed.


# <database> <password> [<charset> <collation>]
# changes MySQL/MariaDB charset and collation for one database - all tables and
# all columns in all tables


[ -n "$DB" ] || exit 1
[ -n "$PW" ]
[ -n "$CHARSET" ] || CHARSET="utf8mb4"
[ -n "$COLL" ] || COLL="utf8mb4_bin"


echo $DB

echo "USE $DB; SHOW TABLES;" | mysql -s "$PW" | (
    while read TABLE; do
        echo $DB.$TABLE


How do I break a string across more than one line of code in JavaScript?

Interesting to note. Tried:

alert("Some \
    string \
    wrapped \
    across \
    mutliples lines.")

And this worked. However, on accident!, there was a space character following the final backslash (all other backslashes were at the end of the line). And this caused an error in the javascript! Removing this space fixed the error, though.

This is in ADT for Android using Cordova.

Setting a JPA timestamp column to be generated by the database?

Add the @CreationTimestamp annotation:

@Column(name="timestamp", nullable = false, updatable = false, insertable = false)
private Timestamp timestamp;

Download all stock symbol list of a market

You can download a list of symbols from here. You have an option to download the whole list directly into excel file. You will have to register though.

Find when a file was deleted in Git

Git log but you need to prefix the path with --


dan-mac:test dani$ git log file1.txt
fatal: ambiguous argument 'file1.txt': unknown revision or path not in the working tree.

dan-mac:test dani$ git log -- file1.txt
 commit 0f7c4e1c36e0b39225d10b26f3dea40ad128b976
 Author: Daniel Palacio <[email protected]>
 Date:   Tue Jul 26 23:32:20 2011 -0500


Submit button not working in Bootstrap form

The .btn classes are designed for , or elements (though some browsers may apply a slightly different rendering).

If you’re using .btn classes on elements that are used to trigger functionality ex. collapsing content, these links should be given a role="button" to adequately communicate their meaning to assistive technologies such as screen readers. I hope this help.

How to set 777 permission on a particular folder?

  1. Right click the folder, click on Properties.
  2. Click on the Security tab
  3. Add the name Everyone to the user list.

PHP: convert spaces in string into %20?

I believe that, if you need to use the %20 variant, you could perhaps use rawurlencode().

Setting JDK in Eclipse

JDK 1.8 have some more enrich feature which doesn't support to many eclipse .

If you didn't find java compliance level as 1.8 in java compiler ,then go ahead and install the below eclipse 32bit or 64 bit depending on your system supports.

  1. Install jdk 1.8 and then set the JAVA_HOME and CLASSPATH in environment variable.
  2. Download eclipse-jee-neon-3-win32 and unzip : supports to java 1.8
  3. Or download Oracle Enterprise Pack for Eclipse ( and unzip :Supports java 1.8 with 64 bit OS
  4. Right click your project > properties
  5. Select “Java Compiler” on left and set java compliance level to 1.8 [select from the dropdown 1.8]
  6. Try running one java program supports to java 8 like lambda expression as below and if no compilation error ,means your eclipse supports to java 1.8, something like this:

    interface testI{
        void show();
    /*class A implements testI{
        public void show(){
    public class LambdaDemo1 {
        public static void main(String[] args) {
            testI test ;
            /*test= new A();
            test = () ->System.out.println("Hello,how are you?"); //lambda 

Batch Extract path and filename from a variable

All of this works for me:

@Echo Off
Echo Directory = %~dp0
Echo Object Name With Quotations=%0
Echo Object Name Without Quotes=%~0
Echo Bat File Drive = %~d0
Echo Full File Name = %~n0%~x0
Echo File Name Without Extension = %~n0
Echo File Extension = %~x0


Directory = D:\Users\Thejordster135\Desktop\Code\BAT\

Object Name With Quotations="D:\Users\Thejordster135\Desktop\Code\BAT\Path_V2.bat"

Object Name Without Quotes=D:\Users\Thejordster135\Desktop\Code\BAT\Path_V2.bat

Bat File Drive = D:

Full File Name = Path.bat

File Name Without Extension = Path

File Extension = .bat

Calculating width from percent to pixel then minus by pixel in LESS CSS

You can escape the calc arguments in order to prevent them from being evaluated on compilation.

Using your example, you would simply surround the arguments, like this:

calc(~'100% - 10px')

Demo :

I find that I use this in one of the following three ways:

Basic Escaping

Everything inside the calc arguments is defined as a string, and is totally static until it's evaluated by the client:

LESS Input

div {
    > span {
        width: calc(~'100% - 10px');

CSS Output

div > span {
  width: calc(100% - 10px);

Interpolation of Variables

You can insert a LESS variable into the string:

LESS Input

div {
    > span {
        @pad: 10px;
        width: calc(~'100% - @{pad}');

CSS Output

div > span {
  width: calc(100% - 10px);

Mixing Escaped and Compiled Values

You may want to escape a percentage value, but go ahead and evaluate something on compilation:

LESS Input

@btnWidth: 40px;
div {
    > span {
        @pad: 10px;
        width: calc(~'(100% - @{pad})' - (@btnWidth * 2));

CSS Output

div > span {
  width: calc((100% - 10px) - 80px);


Constantly print Subprocess output while process is running

This PoC constantly reads the output from a process and can be accessed when needed. Only the last result is kept, all other output is discarded, hence prevents the PIPE from growing out of memory:

import subprocess
import time
import threading
import Queue

class FlushPipe(object):
    def __init__(self):
        self.command = ['python', './']
        self.process = None
        self.process_output = Queue.LifoQueue(0)
        self.capture_output = threading.Thread(target=self.output_reader)

    def output_reader(self):
        for line in iter(self.process.stdout.readline, b''):

    def start_process(self):
        self.process = subprocess.Popen(self.command,

    def get_output_for_processing(self):
        line = self.process_output.get()
        print ">>>" + line

if __name__ == "__main__":
    flush_pipe = FlushPipe()

    now = time.time()
    while time.time() - now < 10:


#!/usr/bin/env python
import time

if __name__ == "__main__":
    while True:
        print str(time.time())

output: You can clearly see that there is only output from ~2.5s interval nothing in between.


Using getline() in C++

I know I'm late but I hope this is useful. Logic is for taking one line at a time if the user wants to enter many lines

int main() 
int t;                    // no of lines user wants to enter
string str;
cin.ignore();            // for clearing newline in cin
    getline(cin,str);    // accepting one line, getline is teminated when newline is found 
return 0; 

input :


Government collage Berhampore

Serampore textile collage

Berhampore Serampore

output :

Government collage Berhampore

Serampore textile collage

Berhampore Serampore

Cloud Firestore collection count

A workaround is to:

write a counter in a firebase doc, which you increment within a transaction everytime you create a new entry

You store the count in a field of your new entry (i.e: position: 4).

Then you create an index on that field (position DESC).

You can do a skip+limit with a query.Where("position", "<" x).OrderBy("position", DESC)

Hope this helps!

Linq select objects in list where exists IN (A,B,C)

Try with Contains function;

Determines whether a sequence contains a specified element.

var allowedStatus = new[]{ "A", "B", "C" };
var filteredOrders = orders.Order.Where(o => allowedStatus.Contains(o.StatusCode));

Http Post With Body

You can try something like this using HttpClient and HttpPost:

List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("mystring", "value_of_my_string"));
// etc...

// Post data to the server
HttpPost httppost = new HttpPost("http://...");
httppost.setEntity(new UrlEncodedFormEntity(params));

HttpClient httpclient = new DefaultHttpClient();
HttpResponse httpResponse = httpclient.execute(httppost);

Checkout subdirectories in Git?

You can't checkout a single directory of a repository because the entire repository is handled by the single .git folder in the root of the project instead of subversion's myriad of .svn directories.

The problem with working on plugins in a single repository is that making a commit to, e.g., mytheme will increment the revision number for myplugin, so even in subversion it is better to use separate repositories.

The subversion paradigm for sub-projects is svn:externals which translates somewhat to submodules in git (but not exactly in case you've used svn:externals before.)

Prevent line-break of span element

Put this in your CSS:


Get more information here:


The white-space property declares how white space inside the element is handled.


normal This value directs user agents to collapse sequences of white space, and break lines as necessary to fill line boxes.

pre This value prevents user agents from collapsing sequences of white space. Lines are only broken at newlines in the source, or at occurrences of "\A" in generated content.

nowrap This value collapses white space as for 'normal', but suppresses line breaks within text.

pre-wrap This value prevents user agents from collapsing sequences of white space. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.

pre-line This value directs user agents to collapse sequences of white space. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.

inherit Takes the same specified value as the property for the element's parent.

In PowerShell, how can I test if a variable holds a numeric value?

Modify your filter like this:

filter isNumeric {

function uses the $input variable to contain pipeline information whereas the filter uses the special variable $_ that contains the current pipeline object.


For a powershell syntax way you can use just a filter (w/o add-type):

filter isNumeric() {
    return $_ -is [byte]  -or $_ -is [int16]  -or $_ -is [int32]  -or $_ -is [int64]  `
       -or $_ -is [sbyte] -or $_ -is [uint16] -or $_ -is [uint32] -or $_ -is [uint64] `
       -or $_ -is [float] -or $_ -is [double] -or $_ -is [decimal]

Android - Handle "Enter" in an EditText

First, you have to set EditText listen to key press

protected void onCreate(Bundle savedInstanceState) {

    // Set the EditText listens to key press
    EditText edittextproductnumber = (EditText) findViewById(;


Second, define the event upon the key press, for example, event to set TextView's text:

public boolean onKey(View v, int keyCode, KeyEvent event) {
    // TODO Auto-generated method stub

 // Listen to "Enter" key press
 if ((event.getAction() == KeyEvent.ACTION_DOWN) && (keyCode == KeyEvent.KEYCODE_ENTER))
     TextView textviewmessage = (TextView) findViewById(;
     textviewmessage.setText("You hit 'Enter' key");
     return true;

return false;   


And finally, do not forget to import EditText,TextView,OnKeyListener,KeyEvent at top:

import android.view.KeyEvent;
import android.view.View.OnKeyListener;
import android.widget.EditText;
import android.widget.TextView;

Convert between UIImage and Base64 string


extension UIImage{
     func toBase64() -> String{
          var imageData = UIImagePNGRepresentation(self)
          return imageData.base64EncodedStringWithOptions(.allZeros)

How to increase font size in NeatBeans IDE?

At Windows in the file C:\Program Files\NetBeans x.x\etc\netbeans.conf

Add "--fontsize [size]" at the end of line netbeans_default_options:

netbeans_default_options=".... --fontsize 16"

Get user's current location

$query = @unserialize (file_get_contents(''));
if ($query && $query['status'] == 'success') {
echo 'Hey user from ' . $query['country'] . ', ' . $query['city'] . '!';
foreach ($query as $data) {
    echo $data . "<br>";

Try this code using this source. it works!

Bitwise and in place of modulus operator

This only works for powers of two (and frequently only positive ones) because they have the unique property of having only one bit set to '1' in their binary representation. Because no other class of numbers shares this property, you can't create bitwise-and expressions for most modulus expressions.

Replacing values from a column using a condition in R

I arrived here from a google search, since my other code is 'tidy' so leaving the 'tidy' way for anyone who else who may find it useful

iris %>% 
  mutate(Species = ifelse(as.character(Species) == "virginica", "newValue", as.character(Species)))

Visual Studio Code PHP Intelephense Keep Showing Not Necessary Error

Here is I solved:

Open the extension settings:

enter image description here

And search for the variable you want to change, and unchecked/checked it

enter image description here

The variables you should consider are:


Delete newline in Vim


cursor in first line





:normal V2jJ

CORS error :Request header field Authorization is not allowed by Access-Control-Allow-Headers in preflight response

If you don't want to install the cors library and instead want to fix your original code, the other step you are missing is that Access-Control-Allow-Origin:* is wrong. When passing Authentication tokens (e.g. JWT) then you must explicitly state every url that is calling your server. You can't use "*" when doing authentication tokens.

Getting the .Text value from a TextBox

Use this instead:

string objTextBox = t.Text;

The object t is the TextBox. The object you call objTextBox is assigned the ID property of the TextBox.

So better code would be:

TextBox objTextBox = (TextBox)sender;
string theText = objTextBox.Text;

What is the best place for storing uploaded images, SQL database or disk file system?

Definitely resize the image, and check it's format if you can. There have been cases of malicious files being uploaded and served by unwitting hosts- for instance, the GIFAR vulnerability allowed you to hide a malicious java applet in a GIF file, which would then be able to read cookies in the current context and send them to another site for a cross-site scripting attack. Resizing the images usually prevents this, as it munges the embedded code. While this attack has been fixed by JVM patches, naively serving up binary files without scrubbing them opens you up to a whole range of vulnerabilities.

Remember, most virus scanners can only run against the filesystem- if you store your binaries in the DB, you won't be able to run a scanner against them very easily.

Verilog: How to instantiate a module

Be sure to check out verilog-mode and especially verilog-auto. It is a verilog mode for emacs, but plugins exist for vi(m?) for example.

An instantiation can be automated with AUTOINST. The comment is expanded with M-x verilog-auto and can afterwards be manually edited.

subcomponent subcomponent_instance_name(/*AUTOINST*/);


subcomponent subcomponent_instance_name (/*AUTOINST*/
  .clk,         (clk)           
  .rst_n,       (rst_n)
  .data_rx      (data_rx_1[9:0]),
  .data_tx      (data_tx[9:0])

Implicit wires can be automated with /*AUTOWIRE*/. Check the link for further information.

How do you add swap to an EC2 instance?

If you are on t2 instances (t2.micro, t2.medium, t2.small), there is no ephemeral or instance storage available to you. So you need to just create your swap in EBS which depending on your use case may or maynot be a good idea. Otherwise follow @David 's answer, and create your swap on the ephemeral storage to avoid paying EBS costs.

More info: there is a table that shows how much ephemeral storage you get for each instance type.

Loop through a date range with JavaScript

Here's a way to do it by making use of the way adding one day causes the date to roll over to the next month if necessary, and without messing around with milliseconds. Daylight savings aren't an issue either.

var now = new Date();
var daysOfYear = [];
for (var d = new Date(2012, 0, 1); d <= now; d.setDate(d.getDate() + 1)) {
    daysOfYear.push(new Date(d));

Note that if you want to store the date, you'll need to make a new one (as above with new Date(d)), or else you'll end up with every stored date being the final value of d in the loop.

Retrieve filename from file descriptor in C

I had this problem on Mac OS X. We don't have a /proc virtual file system, so the accepted solution cannot work.

We do, instead, have a F_GETPATH command for fcntl:

 F_GETPATH          Get the path of the file descriptor Fildes.  The argu-
                    ment must be a buffer of size MAXPATHLEN or greater.

So to get the file associated to a file descriptor, you can use this snippet:

#include <sys/syslimits.h>
#include <fcntl.h>

char filePath[PATH_MAX];
if (fcntl(fd, F_GETPATH, filePath) != -1)
    // do something with the file path

Since I never remember where MAXPATHLEN is defined, I thought PATH_MAX from syslimits would be fine.

Using BufferedReader.readLine() in a while loop properly

You're calling br.readLine() a second time inside the loop.
Therefore, you end up reading two lines each time you go around.

handling dbnull data in

A variation on Steve Wortham's code, to be used nominally with nullable types:

Private Shared Function GetNullable(Of T)(dataobj As Object) As T
    If Convert.IsDBNull(dataobj) Then
        Return Nothing
        Return CType(dataobj, T)
    End If
End Function


mynullable = GetNullable(Of Integer?)(myobj)

You can then query mynullable (e.g., mynullable.HasValue)

Deleting a file in VBA

Here's a tip: are you re-using the file name, or planning to do something that requires the deletion immediately?


You can get VBA to fire the command DEL "C:\TEMP\scratchpad.txt" /F from the command prompt asynchronously using VBA.Shell:

Shell "DEL " & chr(34) & strPath & chr(34) & " /F ", vbHide

Note the double-quotes (ASCII character 34) around the filename: I'm assuming that you've got a network path, or a long file name containing spaces.

If it's a big file, or it's on a slow network connection, fire-and-forget is the way to go. Of course, you never get to see if this worked or not; but you resume your VBA immediately, and there are times when this is better than waiting for the network.

Is it better practice to use String.format over string Concatenation in Java?

Here's a test with multiple sample sizes in milliseconds.

public class Time {

public static String sysFile = "/sys/class/camera/rear/rear_flash";
public static String cmdString = "echo %s > " + sysFile;

public static void main(String[] args) {

  int i = 1;
  for(int run=1; run <= 12; run++){
      for(int test =1; test <= 2 ; test++){
                String.format("\nTEST: %s, RUN: %s, Iterations: %s",run,test,i));
        test(run, i);
      i = i*3;

public static void test(int run, int iterations){

      long start = System.nanoTime();
      for( int i=0;i<iterations; i++){
          String s = "echo " + i + " > "+ sysFile;
      long t = System.nanoTime() - start;   
      String r = String.format("  %-13s =%10d %s", "Concatenation",t,"nanosecond");
      System.out.println(r) ;

     start = System.nanoTime();       
     for( int i=0;i<iterations; i++){
         String s =  String.format(cmdString, i);
     t = System.nanoTime() - start; 
     r = String.format("  %-13s =%10d %s", "Format",t,"nanosecond");

      start = System.nanoTime();          
      for( int i=0;i<iterations; i++){
          StringBuilder b = new StringBuilder("echo ");
          b.append(i).append(" > ").append(sysFile);
          String s = b.toString();
     t = System.nanoTime() - start; 
     r = String.format("  %-13s =%10d %s", "StringBuilder",t,"nanosecond");


TEST: 1, RUN: 1, Iterations: 1
  Concatenation =     14911 nanosecond
  Format        =     45026 nanosecond
  StringBuilder =      3509 nanosecond

TEST: 1, RUN: 2, Iterations: 1
  Concatenation =      3509 nanosecond
  Format        =     38594 nanosecond
  StringBuilder =      3509 nanosecond


TEST: 2, RUN: 1, Iterations: 3
  Concatenation =      8479 nanosecond
  Format        =     94438 nanosecond
  StringBuilder =      5263 nanosecond

TEST: 2, RUN: 2, Iterations: 3
  Concatenation =      4970 nanosecond
  Format        =     92976 nanosecond
  StringBuilder =      5848 nanosecond


TEST: 3, RUN: 1, Iterations: 9
  Concatenation =     11403 nanosecond
  Format        =    287115 nanosecond
  StringBuilder =     14326 nanosecond

TEST: 3, RUN: 2, Iterations: 9
  Concatenation =     12280 nanosecond
  Format        =    209051 nanosecond
  StringBuilder =     11818 nanosecond


TEST: 5, RUN: 1, Iterations: 81
  Concatenation =     54383 nanosecond
  Format        =   1503113 nanosecond
  StringBuilder =     40056 nanosecond

TEST: 5, RUN: 2, Iterations: 81
  Concatenation =     44149 nanosecond
  Format        =   1264241 nanosecond
  StringBuilder =     34208 nanosecond


TEST: 6, RUN: 1, Iterations: 243
  Concatenation =     76018 nanosecond
  Format        =   3210891 nanosecond
  StringBuilder =     76603 nanosecond

TEST: 6, RUN: 2, Iterations: 243
  Concatenation =     91222 nanosecond
  Format        =   2716773 nanosecond
  StringBuilder =     73972 nanosecond


TEST: 8, RUN: 1, Iterations: 2187
  Concatenation =    527450 nanosecond
  Format        =  10291108 nanosecond
  StringBuilder =    885027 nanosecond

TEST: 8, RUN: 2, Iterations: 2187
  Concatenation =    526865 nanosecond
  Format        =   6294307 nanosecond
  StringBuilder =    591773 nanosecond


TEST: 10, RUN: 1, Iterations: 19683
  Concatenation =   4592961 nanosecond
  Format        =  60114307 nanosecond
  StringBuilder =   2129387 nanosecond

TEST: 10, RUN: 2, Iterations: 19683
  Concatenation =   1850166 nanosecond
  Format        =  35940524 nanosecond
  StringBuilder =   1885544 nanosecond


TEST: 12, RUN: 1, Iterations: 177147
  Concatenation =  26847286 nanosecond
  Format        = 126332877 nanosecond
  StringBuilder =  17578914 nanosecond

TEST: 12, RUN: 2, Iterations: 177147
  Concatenation =  24405056 nanosecond
  Format        = 129707207 nanosecond
  StringBuilder =  12253840 nanosecond

For loop in Objective-C

You mean fast enumeration? You question is very unclear.

A normal for loop would look a bit like this:

unsigned int i, cnt = [someArray count];
for(i = 0; i < cnt; i++)
   // do loop stuff
   id someObject = [someArray objectAtIndex:i];

And a loop with fast enumeration, which is optimized by the compiler, would look like this:

for(id someObject in someArray)
   // do stuff with object

Keep in mind that you cannot change the array you are using in fast enumeration, thus no deleting nor adding when using fast enumeration

How to get input text value from inside td

Maybe this will help.

var inputVal = $(this).closest('tr').find("td:eq(x) input").val();

What is the correct way to write HTML using Javascript?

I'm not particularly great at JavaScript or its best practices, but document.write() along with innerHtml() basically allows you to write out strings that may or may not be valid HTML; it's just characters. By using the DOM, you ensure proper, standards-compliant HTML that will keep your page from breaking via plainly bad HTML.

And, as Tom mentioned, JavaScript is done after the page is loaded; it'd probably be a better practice to have the initial setup for your page to be done via standard HTML (via .html files or whatever your server does [i.e. php]).

How to get a float result by dividing two integer values using T-SQL?

If you came here (just like me) to find the solution for integer value, here is the answer:


returns 5

“Origin null is not allowed by Access-Control-Allow-Origin” error for request made by application running from a file:// URL

I use Apache server, so I've used mod_proxy module. Enable modules:

LoadModule proxy_module modules/
LoadModule proxy_http_module modules/

Then add:

ProxyPass /your-proxy-url/ http://service-url:serviceport/

Finally, pass proxy-url to your script.

JPA EntityManager: Why use persist() over merge()?

Persist and merge are for two different purposes (they aren't alternatives at all).

(edited to expand differences information)


  • Insert a new register to the database
  • Attach the object to the entity manager.


  • Find an attached object with the same id and update it.
  • If exists update and return the already attached object.
  • If doesn't exist insert the new register to the database.

persist() efficiency:

  • It could be more efficient for inserting a new register to a database than merge().
  • It doesn't duplicates the original object.

persist() semantics:

  • It makes sure that you are inserting and not updating by mistake.


    AnyEntity newEntity;
    AnyEntity nonAttachedEntity;
    AnyEntity attachedEntity;

    // Create a new entity and persist it        
    newEntity = new AnyEntity();

    // Save 1 to the database at next flush

    // Create a new entity with the same Id than the persisted one.
    AnyEntity nonAttachedEntity = new AnyEntity();

    // Save 2 to the database at next flush instead of 1!!!
    attachedEntity = em.merge(nonAttachedEntity);

    // This condition returns true
    // merge has found the already attached object (newEntity) and returns it.
    if(attachedEntity==newEntity) {
            System.out.print("They are the same object!");

    // Set 3 to value
    // Really, now both are the same object. Prints 3

    // Modify the un attached object has no effect to the entity manager
    // nor to the other objects

This way only exists 1 attached object for any register in the entity manager.

merge() for an entity with an id is something like:

AnyEntity myMerge(AnyEntity entityToSave) {
    AnyEntity attached = em.find(AnyEntity.class, entityToSave.getId());
    if(attached==null) {
            attached = new AnyEntity();
    BeanUtils.copyProperties(attached, entityToSave);

    return attached;

Although if connected to MySQL merge() could be as efficient as persist() using a call to INSERT with ON DUPLICATE KEY UPDATE option, JPA is a very high level programming and you can't assume this is going to be the case everywhere.

How to check status of PostgreSQL server Mac OS X

You probably did not init postgres.

If you installed using HomeBrew, the init must be run before anything else becomes usable.

To see the instructions, run brew info postgres

# Create/Upgrade a Database
If this is your first install, create a database with:
     initdb /usr/local/var/postgres -E utf8

To have launchd start postgresql at login:
   ln -sfv /usr/local/opt/postgresql/*.plist ~/Library/LaunchAgents 
Then to load postgresql now:     
   launchctl load ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist 
Or, if you don't want/need launchctl, you can just run:
    pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start

Once you have run that, it should say something like:

Success. You can now start the database server using:

postgres -D /usr/local/var/postgres or
pg_ctl -D /usr/local/var/postgres -l logfile start

If you are still having issues, check your firewall. If you use a good one like HandsOff! and it was configured to block traffic, then your page will not see the database.

Setting a backgroundImage With React Inline Styles

You can try this with by adding backticks on whole url

style={{backgroundImage:url(${val.image || ''} ) }}

What is causing this error - "Fatal error: Unable to find local grunt"

Could be a few problems here depending on what version of grunt is being used. Newer versions of grunt actually specify that you have a file named Gruntfile.js (instead of the old grunt.js).

You should have the grunt-cli tool be installed globally (this is done via npm install -g grunt-cli). This allows you to actually run grunt commands from the command line.

Secondly make sure you've installed grunt locally for your project. If you see your package.json doesn't have something like "grunt": "0.4.5" in it then you should do npm install grunt --save in your project directory.

Missing Compliance in Status when I add built for internal testing in Test Flight.How to solve?

There's no longer any need to submit a new build or modify Info.plist; instead, follow these steps using an Admin or App Manager account:

  1. Go to the iOS tab at the top left of TestFlight and click the yellow triangle next to the warning to provide this information within iTunes Connect:

enter image description here

  1. Click the "Provide Export Compliance Information" link in the popup:

Export Compliance Information

Though, if you do choose to modify Info.plist, you'll never need to deal with this popup again.

Waiting for another flutter command to release the startup lock

You can remove flutter and "install again", so fastest way is to:

1) Check where you have flutter (as executable)

To check it, you can run:

which flutter

And you can expect such output:


2) Go to this directory

Above path is directly to flutter, but we would like to go to directory so "one earlier" in path:

cd /your_user/your_path/flutter/bin

3) Check is it git repository

It should be, but it's worth to check.

Run one of the git command e.g.

git status


git branch

When it's git repository you will receive some info about it or correct list of branches.

4) Remove all of the files

rm -R *

5) "revert" removal to have only necessary files:

git co -- .

6) Voila!

You can run just flutter version and commands should work (and Flutter will fetch some necessary data).

node.js - request - How to "emitter.setMaxListeners()"?

It also happened to me

I use this code and it worked

require('events').EventEmitter.defaultMaxListeners = infinity;

Try it out. It may help


In c# is there a method to find the max of 3 numbers?

off topic but here is the formula for middle value.. just in case someone is looking for it

Math.Min(Math.Min(Math.Max(x,y), Math.Max(y,z)), Math.Max(x,z));

Can I run a 64-bit VMware image on a 32-bit machine?

I honestly doubt it, for a number of reasons, but the most important one is that there are some instructions that are allowed in 32-bit mode, but not in 64-bit mode. Specifically, the REX prefix that is used to encode some instructions and registers in 64-bit mode is a byte of the form 0x4f:0x40, but in 32 bit mode the same byte is either INC or DEC with a fixed operand.
Because of this, any 64-bit instruction that is prefixed by REX will be interpreted as either INC or DEC, and won't give the VMM the chance to emulate the 64-bit instruction (for instance by signaling an undefined opcode exception).

The only way it might be done is to use a trap exception to return to the VMM after each and every instruction so that it can see if it needs special 64-bit handling. I simply can't see that happening.

How to bind a List to a ComboBox?

public MainWindow(){
    List<person> personList = new List<person>();

    personList.Add(new person { name = "rob", age = 32 } );
    personList.Add(new person { name = "annie", age = 24 } );
    personList.Add(new person { name = "paul", age = 19 } );

    comboBox1.DataSource = personList;
    comboBox1.DisplayMember = "name";

    comboBox1.SelectionChanged += new SelectionChangedEventHandler(comboBox1_SelectionChanged);

void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
    person selectedPerson = comboBox1.SelectedItem as person;
    messageBox.Show(, "caption goes here");


JQuery DatePicker ReadOnly

I solved this with selector. I do not initialize the datetime picker on inputs which are readonly.


Writing File to Temp Folder

For %appdata% take a look to


ASP.NET MVC Bundle not rendering script files on staging server. It works on development server

Whenever I set debug="off" in my web.config and run my mvc4 application i would end up with ...

<script src="/bundles/jquery?v=<some long string>"></script>

in my html code and a JavaScript error

Expected ';'

There were 2 ways to get rid of the javascript error

  1. set BundleTable.EnableOptimizations = false in BundleConfig.cs


  1. I ended up using NuGet Package Manager to update WebGrease.dll. It works fine irrespective if debug= "true" or debug = "false".

What is base 64 encoding used for?

One hexadecimal digit is of one nibble (4 bits). Two nibbles make 8 bits which are also called 1 byte.

MD5 generates a 128-bit output which is represented using a sequence of 32 hexadecimal digits, which in turn are 32*4=128 bits. 128 bits make 16 bytes (since 1 byte is 8 bits).

Each Base64 character encodes 6 bits (except the last non-pad character which can encode 2, 4 or 6 bits; and final pad characters, if any). Therefore, per Base64 encoding, a 128-bit hash requires at least ?128/6? = 22 characters, plus pad if any.

Using base64, we can produce the encoded output of our desired length (6, 8, or 10). If we choose to decide 8 char long output, it occupies only 8 bytes whereas it was occupying 16 bytes for 128-bit hash output.

So, in addition to security, base64 encoding is also used to reduce the space consumed.

Can I use GDB to debug a running process?

ps -elf doesn't seem to show the PID. I recommend using instead:

ps -ld | grep foo
gdb -p PID

How to install ADB driver for any android device?

You don't really need to install or use any third party tools.

The drivers located in ...\Android\Sdk\extras\google\usb_driver work just fine.

Step 1: In Device Manager, Right click on the malfunctioning Android ADB Interface driver

Step 2: Select Update Driver Software

Step 3: Select Browse my computer for driver software

Step 4: Select Let me pick from a list of device drivers on my computer

Step 5: Select Have Disk

This window pops up:

enter image description here

Step 6: Copy the location of the Google USB Driver (...\Android\Sdk\extras\google\usb_driver) or browse to it.

Step 7: Click Ok

This window pops up:

enter image description here

Step 8: Select Android ADB Interface and click Next

The window below pops up with a warning:

enter image description here

That's it. You driver installation will start and in a few seconds, you should be able to see your device

updating nodejs on ubuntu 16.04

Please refer nodejs official site for installation instructions at the following link

Anyway, please find the commands to install nodejs version 10 in ubuntu below.

curl -sL | sudo -E bash -
sudo apt-get install -y nodejs

INNER JOIN same table

Perhaps this should be the select (if I understand the question correctly)

select user.user_fname, user.user_lname, parent.user_fname, parent.user_lname
... As before

Manually Set Value for FormBuilder Control

  let cloneObj = Object.assign({}, this.form.getRawValue(), someClass);

If you don't want manually set each field.

how to refresh page in angular 2

Just in case someone else encounters this problem. You need to call


And you cannot call this from a expression. If you want to call this from a click event you need to put this on a function:


And simply define the function:

reloadPage() {

If you are changing the route, it might not work because the click event seems to happen before the route changes. A very dirty solution is just to add a small delay

reloadPage() {
    }, 100);

String date to xmlgregoriancalendar conversion

For me the most elegant solution is this one:

XMLGregorianCalendar result = DatatypeFactory.newInstance()

Using Java 8.

Extended example:

XMLGregorianCalendar result = DatatypeFactory.newInstance()

This prints out:


Razor-based view doesn't see referenced assemblies

I was getting a similar error after moving my dev machine from Win7 32bit to Win7 64bit. Error message:

...\Web\Views\Login.cshtml: runtime error: [A]System.Web.WebPages.Razor.Configuration.HostSection cannot be cast to [B]System.Web.WebPages.Razor.Configuration.HostSection. Type A originates from System.Web.WebPages.Razor, Version= ... Type B originates from ... Version=

Turns out I had both versions in the GAC. The View web.config referenced v1 but the app was referencing v2. Removed the referenced assemblies and re-added v1. of System.Web.WebPages.Razor, etc.

How to read a line from a text file in c/c++?

getline() is what you're looking for. You use strings in C++, and you don't need to know the size ahead of time.

Assuming std namespace:

 ifstream file1("myfile.txt");
 string stuff;

 while (getline(file1, stuff, '\n')) {
      cout << stuff << endl;


pandas groupby sort within groups

Here's other example of taking top 3 on sorted order, and sorting within the groups:

In [43]: import pandas as pd                                                                                                                                                       

In [44]:  df = pd.DataFrame({"name":["Foo", "Foo", "Baar", "Foo", "Baar", "Foo", "Baar", "Baar"], "count_1":[5,10,12,15,20,25,30,35], "count_2" :[100,150,100,25,250,300,400,500]})

In [45]: df                                                                                                                                                                        
   count_1  count_2  name
0        5      100   Foo
1       10      150   Foo
2       12      100  Baar
3       15       25   Foo
4       20      250  Baar
5       25      300   Foo
6       30      400  Baar
7       35      500  Baar

### Top 3 on sorted order:
In [46]: df.groupby(["name"])["count_1"].nlargest(3)                                                                                                                               
Baar  7    35
      6    30
      4    20
Foo   5    25
      3    15
      1    10
dtype: int64

### Sorting within groups based on column "count_1":
In [48]: df.groupby(["name"]).apply(lambda x: x.sort_values(["count_1"], ascending = False)).reset_index(drop=True)
   count_1  count_2  name
0       35      500  Baar
1       30      400  Baar
2       20      250  Baar
3       12      100  Baar
4       25      300   Foo
5       15       25   Foo
6       10      150   Foo
7        5      100   Foo

Converting a list to a set changes element order

Answering your first question, a set is a data structure optimized for set operations. Like a mathematical set, it does not enforce or maintain any particular order of the elements. The abstract concept of a set does not enforce order, so the implementation is not required to. When you create a set from a list, Python has the liberty to change the order of the elements for the needs of the internal implementation it uses for a set, which is able to perform set operations efficiently.

How do I make JavaScript beep?


You can now use base64 files to produce sounds when imported as data URI. The solution is almost the same as the previous ones, except you do not need to import an external audio file.

function beep() {
    var snd = new Audio("data:audio/wav;base64,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");;


Data URI is supported on almost every browser now. More information on


Conversion Tool

And here is where you can convert mp3 or wav files into Data URI format:

How to empty a list in C#?

Option #1: Use Clear() function to empty the List<T> and retain it's capacity.

  • Count is set to 0, and references to other objects from elements of the collection are also released.

  • Capacity remains unchanged.

Option #2 - Use Clear() and TrimExcess() functions to set List<T> to initial state.

  • Count is set to 0, and references to other objects from elements of the collection are also released.

  • Trimming an empty List<T> sets the capacity of the List to the default capacity.


Count = number of elements that are actually in the List<T>

Capacity = total number of elements the internal data structure can hold without resizing.

Clear() Only

List<string> dinosaurs = new List<string>();    
Console.WriteLine("Count: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
Console.WriteLine("\nCount: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);

Clear() and TrimExcess()

List<string> dinosaurs = new List<string>();
Console.WriteLine("Count: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
Console.WriteLine("\nClear() and TrimExcess()");
Console.WriteLine("\nCount: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);

What does API level mean?

API level is basically the Android version. Instead of using the Android version name (eg 2.0, 2.3, 3.0, etc) an integer number is used. This number is increased with each version. Android 1.6 is API Level 4, Android 2.0 is API Level 5, Android 2.0.1 is API Level 6, and so on.

Eclipse: How to install a plugin manually?

You can try this

click Help>Install New Software on the menu bar

enter image description here

enter image description here

enter image description here

enter image description here

VBA - Select columns using numbers?

You can specify addresses as "R1C2" instead of "B2". Under File -> Options -> Formuals -> Workingg with Formulas there is a toggle R1C1 reference style. which can be set, as illustrated below.

enter image description here

Rollback a Git merge

Reverting a merge commit has been exhaustively covered in other questions. When you do a fast-forward merge, the second one you describe, you can use git reset to get back to the previous state:

git reset --hard <commit_before_merge>

You can find the <commit_before_merge> with git reflog, git log, or, if you're feeling the moxy (and haven't done anything else): git reset --hard HEAD@{1}

Search for executable files using find command

It is SO ridiculous that this is not super-easy... let alone next to impossible. Hands up, I defer to Apple/Spotlight...

mdfind 'kMDItemContentType=public.unix-executable'

At least it works!

Extracting text from a PDF file using PDFMiner in python?

Full disclosure, I am one of the maintainers of pdfminer.six.

Nowadays, there are multiple api's to extract text from a PDF, depending on your needs. Behind the scenes, all of these api's use the same logic for parsing and analyzing the layout.

(All the examples assume your PDF file is called example.pdf)


If you want to extract text just once you can use the commandline tool

$ example.pdf

High-level api

If you want to extract text with Python, you can use the high-level api. This approach is the go-to solution if you want to extract text programmatically from many PDF's.

from pdfminer.high_level import extract_text

text = extract_text('example.pdf')

Composable api

There is also a composable api that gives a lot of flexibility in handling the resulting objects. For example, you can implement your own layout algorithm using that. This method is suggested in the other answers, but I would only recommend this when you need to customize the way pdfminer.six behaves.

from io import StringIO

from pdfminer.converter import TextConverter
from pdfminer.layout import LAParams
from pdfminer.pdfdocument import PDFDocument
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.pdfpage import PDFPage
from pdfminer.pdfparser import PDFParser

output_string = StringIO()
with open('example.pdf', 'rb') as in_file:
    parser = PDFParser(in_file)
    doc = PDFDocument(parser)
    rsrcmgr = PDFResourceManager()
    device = TextConverter(rsrcmgr, output_string, laparams=LAParams())
    interpreter = PDFPageInterpreter(rsrcmgr, device)
    for page in PDFPage.create_pages(doc):


javax.servlet.ServletException cannot be resolved to a type in spring web app

import javax.servlet


Go to properties of your project ( with Alt+Enter or righ-click )


check on Apache Tomcat v7.0 under Targeted Runtime and it works.


Java - How to create new Entry (key, value)

You can just implement the Map.Entry<K, V> interface yourself:

import java.util.Map;

final class MyEntry<K, V> implements Map.Entry<K, V> {
    private final K key;
    private V value;

    public MyEntry(K key, V value) {
        this.key = key;
        this.value = value;

    public K getKey() {
        return key;

    public V getValue() {
        return value;

    public V setValue(V value) {
        V old = this.value;
        this.value = value;
        return old;

And then use it:

Map.Entry<String, Object> entry = new MyEntry<String, Object>("Hello", 123);

how to specify new environment location for conda create

If you want to use the --prefix or -p arguments, but want to avoid having to use the environment's full path to activate it, you need to edit the .condarc config file before you create the environment.

The .condarc file is in the home directory; C:\Users\<user> on Windows. Edit the values under the envs_dirs key to include the custom path for your environment. Assuming the custom path is D:\envs, the file should end up looking something like this:

ssl_verify: true
  - defaults
  - C:\Users\<user>\Anaconda3\envs
  - D:\envs

Then, when you create a new environment on that path, its name will appear along with the path when you run conda env list, and you should be able to activate it using only the name, and not the full path.

Command line screenshot

In summary, if you edit .condarc to include D:\envs, and then run conda env create -p D:\envs\myenv python=x.x, then activate myenv (or source activate myenv on Linux) should work.

Hope that helps!

P.S. I stumbled upon this through trial and error. I think what happens is when you edit the envs_dirs key, conda updates ~\.conda\environments.txt to include the environments found in all the directories specified under the envs_dirs, so they can be accessed without using absolute paths.

How to print multiple variable lines in Java

Suppose we have variable date , month and year then we can write it in the java like this.

int date=15,month=4,year=2016;
System.out.println(date+ "/"+month+"/"+year);

output of this will be like below:


PHP - check if variable is undefined

An another way is simply :

    echo "Yes 1";
    echo "Yes 2";

$test = "hello";

    echo "Yes 3";

Will return :

"Yes 3"

The best way is to use isset(), otherwise you can have an error like "undefined $test".

You can do it like this :

if( isset($test) && ($test!==null) )

You'll not have any error because the first condition isn't accepted.

nullable object must have a value

I got this message when trying to access values of a null valued object.

sName = myObj.Name;

this will produce error. First you should check if object not null

if(myObj != null)
  sName = myObj.Name;

This works.

Use mysql_fetch_array() with foreach() instead of while()

You can code like this:

$query_select = "SELECT * FROM shouts ORDER BY id DESC LIMIT 8;";
$result_select = mysql_query($query_select) or die(mysql_error());
$rows = array();
while($row = mysql_fetch_array($result_select))
    $rows[] = $row;
foreach($rows as $row){ 
    $ename = stripslashes($row['name']);
    $eemail = stripcslashes($row['email']);
    $epost = stripslashes($row['post']);
    $eid = $row['id'];

    $grav_url = "".md5(strtolower($eemail))."&size=70";

    echo ('<img src = "' . $grav_url . '" alt="Gravatar">'.'<br/>');

    echo $eid . '<br/>';

    echo $ename . '<br/>';

    echo $eemail . '<br/>';

    echo $epost . '<br/><br/><br/><br/>';

As you can see, it's still need a loop while to get data from mysql_fetch_array

How to tell a Mockito mock object to return something different the next time it is called?

For Anyone using spy() and the doReturn() instead of the when() method:

what you need to return different object on different calls is this:



For classic mocks:

when(this.mockFoo.someMethod()).thenReturn(obj1, obj2);

or with an exception being thrown:

        .thenThrow(new IllegalArgumentException())
        .thenReturn(obj2, obj3);

MetadataException when using Entity Framework Entity Connection

There are several possible catches. I think that the most common error is in this part of the connection string:


This is no magic. Once you understand what is stands for you'll get the connection string right.

First the xxx part. That's nothing else than an assembly name where you defined you EF context clas. Usually it would be something like MyProject.Data. Default value is * which stands for all loaded assemblies. It's always better to specify a particular assembly name.

Now the yyy part. That's a resource name in the xxx assembly. It will usually be something like a relative path to your .edmx file with dots instead of slashes. E.g. Models/Catalog - Models.Catalog The easiest way to get the correct string for your application is to build the xxx assembly. Then open the assembly dll file in a text editor (I prefer the Total Commander's default viewer) and search for ".csdl". Usually there won't be more than 1 occurence of that string.

Your final EF connection string may look like this:


Entity Framework - Generating Classes

  1. Open the EDMX model
  2. Right click -> Update Model from Browser -> Stored Procedure -> Select your stored procedure -> Finish
  3. See the Model Browser popping up next to Solution Explorer.
  4. Go to Function Imports -> Right click on your Stored Procedure -> Add Function Import
  5. Select the Entities under Return a Collection of -> Select your Entity name from the drop down
  6. Build your Solution.

Get second child using jQuery

grab the second child:


or, grab the second child <td>:


See documentation for children and eq.

Regex pattern for numeric values

This will allow decimal numbers (or whole numbers) that don't start with zero:


If you want to allow numbers that start with zero, you can do :


Loop structure inside gnuplot?

Here is the alternative command:

gnuplot -p -e 'plot for [file in system("find . -name \\*.txt -depth 1")] file using 1:2 title file with lines'

Close/kill the session when the browser or tab is closed

Please refer the below steps:

  1. First create a page SessionClear.aspx and write the code to clear session
  2. Then add following JavaScript code in your page or Master Page:

    <script language="javascript" type="text/javascript">
        var isClose = false;
        //this code will handle the F5 or Ctrl+F5 key
        //need to handle more cases like ctrl+R whose codes are not listed here
        document.onkeydown = checkKeycode
        function checkKeycode(e) {
        var keycode;
        if (window.event)
        keycode = window.event.keyCode;
        else if (e)
        keycode = e.which;
        if(keycode == 116)
        isClose = true;
        function somefunction()
        isClose = true;
            function bodyUnload() {
                  var request = GetRequest();
        "GET", "SessionClear.aspx", true);
            function GetRequest() {
                var request = null;
                if (window.XMLHttpRequest) {
                    //incase of IE7,FF, Opera and Safari browser
                    request = new XMLHttpRequest();
                else {
                    //for old browser like IE 6.x and IE 5.x
                    request = new ActiveXObject('MSXML2.XMLHTTP.3.0');
                return request;
  3. Add the following code in the body tag of master page.

    <body onbeforeunload="bodyUnload();" onmousedown="somefunction()">

How do I grab an INI value within a shell script?

How about grepping for that line then using awk

version=$(awk -F "=" '/database_version/ {print $2}' parameters.ini)

How to set the part of the text view is clickable

 t= (TextView) findViewById(;

 t.setText(Html.fromHtml("<bThis is normal text </b>" +
                "<a href=\"\">This is cliclable text</a> "));

JavaFX "Location is required." even though it is in the same package

I couldn't use


because I put my controller class into "controllers" package, so here is my solution:


What does git rev-parse do?

git rev-parse Also works for getting the current branch name using the --abbrev-ref flag like:

git rev-parse --abbrev-ref HEAD

Setting session variable using javascript

You could better use the localStorage of the web browser.

You can find a reference here

Simple VBA selection: Selecting 5 cells to the right of the active cell

This copies the 5 cells to the right of the activecell. If you have a range selected, the active cell is the top left cell in the range.

Sub Copy5CellsToRight()
    ActiveCell.Offset(, 1).Resize(1, 5).Copy
End Sub

If you want to include the activecell in the range that gets copied, you don't need the offset:

Sub ExtendAndCopy5CellsToRight()
    ActiveCell.Resize(1, 6).Copy
End Sub

Note that you don't need to select before copying.

How to check if running in Cygwin, Mac or Linux?

Here is the bash script I used to detect three different OS type (GNU/Linux, Mac OS X, Windows NT)

Pay attention

  • In your bash script, use #!/usr/bin/env bash instead of #!/bin/sh to prevent the problem caused by /bin/sh linked to different default shell in different platforms, or there will be error like unexpected operator, that's what happened on my computer (Ubuntu 64 bits 12.04).
  • Mac OS X 10.6.8 (Snow Leopard) do not have expr program unless you install it, so I just use uname.


  1. Use uname to get the system information (-s parameter).
  2. Use expr and substr to deal with the string.
  3. Use if elif fi to do the matching job.
  4. You can add more system support if you want, just follow the uname -s specification.


#!/usr/bin/env bash

if [ "$(uname)" == "Darwin" ]; then
    # Do something under Mac OS X platform        
elif [ "$(expr substr $(uname -s) 1 5)" == "Linux" ]; then
    # Do something under GNU/Linux platform
elif [ "$(expr substr $(uname -s) 1 10)" == "MINGW32_NT" ]; then
    # Do something under 32 bits Windows NT platform
elif [ "$(expr substr $(uname -s) 1 10)" == "MINGW64_NT" ]; then
    # Do something under 64 bits Windows NT platform


  • Linux (Ubuntu 12.04 LTS, Kernel 3.2.0) tested OK.
  • OS X (10.6.8 Snow Leopard) tested OK.
  • Windows (Windows 7 64 bit) tested OK.

What I learned

  1. Check for both opening and closing quotes.
  2. Check for missing parentheses and braces {}


how to implement login auth in node.js

@alessioalex answer is a perfect demo for fresh node user. But anyway, it's hard to write checkAuth middleware into all routes except login, so it's better to move the checkAuth from every route to one entry with app.use. For example:

function checkAuth(req, res, next) {
  // if logined or it's login request, then go next route
  if (isLogin || (req.path === '/login' && req.method === 'POST')) {
  } else {
    res.send('Not logged in yet.')

app.use('/', checkAuth)

Install apps silently, with granted INSTALL_PACKAGES permission

Try this LD_LIBRARY_PATH=/vendor/lib:/system/lib before pm install. It works well.

CSS: Truncate table cells, but fit as much as possible

Yep I would say thirtydot has it, there is no way to do it unless you use a js method. You are talking about a complex set of rendering conditions that you will have to define. e.g. what happens when both cells are getting too big for their apartments you will have to decide who has priority or simply just give them a percentage of the area and if they are overfull they will both take up that area and only if one has whitespace will you stretch your legs in the other cell, either way there is no way to do it with css. Although there are some pretty funky things people do with css that I have not thought of. I really doubt you can do this though.

Create a variable name with "paste" in R?

In my case function eval() works very good. Below I generate 10 variables and assign them 10 values.

lhs <- rnorm(10)
rhs <- paste("perf.a", 1:10, "<-", lhs, sep="")

how to implement Interfaces in C++?

There is no concept of interface in C++,
You can simulate the behavior using an Abstract class.
Abstract class is a class which has atleast one pure virtual function, One cannot create any instances of an abstract class but You could create pointers and references to it. Also each class inheriting from the abstract class must implement the pure virtual functions in order that it's instances can be created.

Spring Boot: How can I set the logging level with

Existing answers are greats. I just want to share with you a new spring boot feature allowing to group logs and set logging level on the whole group.

Exemple from the docs :

  • Create a logging group, org.apache.coyote, org.apache.tomcat
  • Set the logging level for group

It's nice feature which brings more flexibility.

"Parser Error Message: Could not load type" in Global.asax

I have to report that I tried at least 4 suggestions from this post. None of them worked. Yet I am happy to report that I recovered by retrieving from back up. Only had to update my last code changes from log file. Took less then 10 minutes. Spent 3 times that reading this post and trying other suggestions. Sorry.

It was a very weird error. Good luck to anyone else encountering this gremlin.

Generate a dummy-variable

I read this on the kaggle forum:

#Generate example dataframe with character column
example <-"A", "A", "B", "F", "C", "G", "C", "D", "E", "F"))
names(example) <- "strcol"

#For every unique value in the string column, create a new 1/0 column
#This is what Factors do "under-the-hood" automatically when passed to function requiring numeric data
for(level in unique(example$strcol)){
  example[paste("dummy", level, sep = "_")] <- ifelse(example$strcol == level, 1, 0)

Clear and refresh jQuery Chosen dropdown list

Using .trigger("chosen:updated"); you can update the options list after appending.

Updating Chosen Dynamically: If you need to update the options in your select field and want Chosen to pick up the changes, you'll need to trigger the "chosen:updated" event on the field. Chosen will re-build itself based on the updated content.

Your code:

        $('#picturegallery').empty(); //remove all child nodes
        var newOption = $('<option value="1">test</option>');

CSV parsing in Java - working example..?

At a minimum you are going to need to know the column delimiter.

Page loaded over HTTPS but requested an insecure XMLHttpRequest endpoint

Try to add a s after http

Like this: =>

It works for me

Enter key press in C#

You could use this code:

abc_KeyDown(abc, new KeyEventArgs(Keys.Enter));

Javascript Append Child AFTER Element

You need to append the new element to existing element's parent before element's next sibling. Like:

var parentGuest = document.getElementById("one");
var childGuest = document.createElement("li"); = "two";
parentGuest.parentNode.insertBefore(childGuest, parentGuest.nextSibling);

Or if you want just append it, then:

var parentGuest = document.getElementById("one"); 
var childGuest = document.createElement("li"); = "two"; 

Gray out image with CSS?

Considering filter:expression is a Microsoft extension to CSS, so it will only work in Internet Explorer. If you want to grey it out, I would recommend that you set it's opacity to 50% using a bit of javascript. would be a good place to start, because it discusses an opacity script that works with Firefox, Safari, KHTML, Internet Explorer and CSS3 capable browsers.

You might also want to give it a grey border.

Viewing all defined variables

This has to be defined in the interactive shell:

def MyWho():
    print [v for v in globals().keys() if not v.startswith('_')]

Then the following code can be used as an example:

>>> import os
>>> import sys
>>> a = 10 
>>> MyWho()
['a', 'MyWho', 'sys', 'os']

Color Tint UIButton Image

If you have a custom button with a background image.You can set the tint color of your button and override the image with following .

In assets select the button background you want to set tint color.

In the attribute inspector of the image set the value render as to "Template Image"

enter image description here

Now whenever you setbutton.tintColor = you button will be shown in red.

How to iterate through an ArrayList of Objects of ArrayList of Objects?

You want to follow the same pattern as before:

for (Type curInstance: CollectionOf<Type>) {
  // use currInstance

In this case it would be:

for (Bullet bullet : gunList.get(2).getBullet()) {

How to pass a view's onClick event to its parent on Android?

If your TextView create click issues, than remove android:inputType="" from your xml file.

Bad Gateway 502 error with Apache mod_proxy and Tomcat

Just to add some specific settings, I had a similar setup (with Apache 2.0.63 reverse proxying onto Tomcat 5.0.27).

For certain URLs the Tomcat server could take perhaps 20 minutes to return a page.

I ended up modifying the following settings in the Apache configuration file to prevent it from timing out with its proxy operation (with a large over-spill factor in case Tomcat took longer to return a page):

Timeout 5400
ProxyTimeout 5400

Some backgound

ProxyTimeout alone wasn't enough. Looking at the documentation for Timeout I'm guessing (I'm not sure) that this is because while Apache is waiting for a response from Tomcat, there is no traffic flowing between Apache and the Browser (or whatever http client) - and so Apache closes down the connection to the browser.

I found that if I left the Timeout setting at its default (300 seconds), then if the proxied request to Tomcat took longer than 300 seconds to get a response the browser would display a "502 Proxy Error" page. I believe this message is generated by Apache, in the knowledge that it's acting as a reverse proxy, before it closes down the connection to the browser (this is my current understanding - it may be flawed).

The proxy error page says:

Proxy Error

The proxy server received an invalid response from an upstream server. The proxy server could not handle the request GET.

Reason: Error reading from remote server

...which suggests that it's the ProxyTimeout setting that's too short, while investigation shows that Apache's Timeout setting (timeout between Apache and the client) that also influences this.

WCF Error - Could not find default endpoint element that references contract 'UserService.UserService'

This problem occures when you use your service via other application.If application has config file just add your service config information to this file. In my situation there wasn't any config file so I use this technique and it worked fine.Just store url address in application,read it and using BasicHttpBinding() method send it to service application as parameter.This is simple demonstration how I did it:

Configuration config = new Configuration(dataRowSet[0]["ServiceUrl"].ToString());

var remoteAddress = new System.ServiceModel.EndpointAddress(config.Url);

SimpleService.PayPointSoapClient client = 
    new SimpleService.PayPointSoapClient(new System.ServiceModel.BasicHttpBinding(), 
SimpleService.AccountcredResponse response = client.AccountCred(request);

Axios get in url works but with second parameter as object it doesn't

axios.get accepts a request config as the second parameter (not query string params).

You can use the params config option to set query string params as follows:

axios.get('/api', {
  params: {
    foo: 'bar'

Adding days to a date in Python

This might help:

from datetime import date, timedelta
date1 = date(2011, 10, 10)
date2 = date + timedelta(days=5)
print (date2)

How can I open multiple files using "with open" in Python?

From Python 3.10 there is a new feature of Parenthesized context managers, which permits syntax like:

with (
    open("a", "w") as a,
    open("b", "w") as b

How to export the Html Tables data into PDF using Jspdf

Here is an example I think that will help you

<!DOCTYPE html>
<script src="js/min.js"></script>
<script src="js/pdf.js"></script>
         var doc = new jsPDF();
    var specialElementHandlers = {
        '#editor': function (element, renderer) {
            return true;

   $('#cmd').click(function () {

        var table = tableToJson($('#StudentInfoListTable').get(0))
        var doc = new jsPDF('p','pt', 'a4', true);
        $.each(table, function (i, row){
            $.each(row, function (j, cell){
                doc.cell(10, 50,120, 50, cell, i);  // 2nd parameter=top margin,1st=left margin 3rd=row cell width 4th=Row height
    function tableToJson(table) {
    var data = [];

    // first row needs to be headers
    var headers = [];
    for (var i=0; i<table.rows[0].cells.length; i++) {
        headers[i] = table.rows[0].cells[i].innerHTML.toLowerCase().replace(/ /gi,'');

    // go through cells
    for (var i=0; i<table.rows.length; i++) {

        var tableRow = table.rows[i];
        var rowData = {};

        for (var j=0; j<tableRow.cells.length; j++) {

            rowData[ headers[j] ] = tableRow.cells[j].innerHTML;



    return data;
<div id="table">
<table id="StudentInfoListTable">
                        <th>S.S.C Roll</th>
                        <th>S.S.C Division</th>
                        <th>H.S.C Roll</th>
                        <th>H.S.C Division</th>


                            <td>alimon  </td>
<button id="cmd">Submit</button>

Here the output

enter image description here

Twitter bootstrap collapse: change display of toggle button

Add some jquery code, you need jquery to do this :

        $(".btn[data-toggle='collapse']").click(function() {
            if ($(this).text() == '+') {
            } else {

Send Post Request with params using Retrofit

I have found the solution. The issue was a problem in my classes structure. So i updated them like the following samples.

public class LandingPageReport {

    private ArrayList<LandingPageReportItem> GetDetailWithMonthWithCodeResult;

    // + Getter Setter methods

public class LandingPageReportItem {

    private String code;

    private String field1;

    // + Getter Setter methods

And then i use this retrofit configuration

void getLandingPageReport(@Field("code") String code,
                          @Field("monthact") String monthact,
                          Callback<LandingPageReport> cb);

Catching an exception while using a Python 'with' statement

from __future__ import with_statement

    with open( "a.txt" ) as f :
        print f.readlines()
except EnvironmentError: # parent of IOError, OSError *and* WindowsError where available
    print 'oops'

If you want different handling for errors from the open call vs the working code you could do:

    f = open('foo.txt')
except IOError:
    with f:
        print f.readlines()

Remove shadow below actionbar

What is the style item to make it disappear?

In order to remove the shadow add this to your app theme:

<style name="MyAppTheme" parent="android:Theme.Holo.Light">
    <item name="android:windowContentOverlay">@null</item>

UPDATE: As @Quinny898 stated, on Android 5.0 this has changed, you have to call setElevation(0) on your action bar. Note that if you're using the support library you must call it to that like so:


Undo git pull, how to bring repos to old state

git pull do below operation.

i. git fetch

ii. git merge

To undo pull do any operation:

i. git reset --hard --- its revert all local change also


ii. git reset --hard master@{5.days.ago} (like 10.minutes.ago, 1.hours.ago, 1.days.ago ..) to get local changes.


iii. git reset --hard commitid


Next time use git pull --rebase instead of git pull.. its sync server change by doing ( fetch & merge).

Java - Convert String to valid URI object

I'm going to add one suggestion here aimed at Android users. You can do this which avoids having to get any external libraries. Also, all the search/replace characters solutions suggested in some of the answers above are perilous and should be avoided.

Give this a try:

String urlStr = " 15sec h.264.mp4";
URL url = new URL(urlStr);
URI uri = new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef());
url = uri.toURL();

You can see that in this particular URL, I need to have those spaces encoded so that I can use it for a request.

This takes advantage of a couple features available to you in Android classes. First, the URL class can break a url into its proper components so there is no need for you to do any string search/replace work. Secondly, this approach takes advantage of the URI class feature of properly escaping components when you construct a URI via components rather than from a single string.

The beauty of this approach is that you can take any valid url string and have it work without needing any special knowledge of it yourself.

Create directory if it does not exist

I wanted to be able to easily let users create a default profile for PowerShell to override some settings, and ended up with the following one-liner (multiple statements yes, but can be pasted into PowerShell and executed at once, which was the main goal):

cls; [string]$filePath = $profile; [string]$fileContents = '<our standard settings>'; if(!(Test-Path $filePath)){md -Force ([System.IO.Path]::GetDirectoryName($filePath)) | Out-Null; $fileContents | sc $filePath; Write-Host 'File created!'; } else { Write-Warning 'File already exists!' };

For readability, here's how I would do it in a .ps1 file instead:

cls; # Clear console to better notice the results
[string]$filePath = $profile; # Declared as string, to allow the use of texts without plings and still not fail.
[string]$fileContents = '<our standard settings>'; # Statements can now be written on individual lines, instead of semicolon separated.
if(!(Test-Path $filePath)) {
  New-Item -Force ([System.IO.Path]::GetDirectoryName($filePath)) | Out-Null; # Ignore output of creating directory
  $fileContents | Set-Content $filePath; # Creates a new file with the input
  Write-Host 'File created!';
else {
  Write-Warning "File already exists! To remove the file, run the command: Remove-Item $filePath";

How to get ID of button user just clicked?

$("button").click(function() {
    alert(; // or alert($(this).attr('id'));

java.lang.ClassNotFoundException on working app

I know this question has been answered, and it likely wasn't the case. But I was getting this error, and figured I'd post why in case it can be helpful to anyone else.

So I was getting this error, and after several hours sheepishly realized that I had unchecked 'Project > Build Automatically'. So although I had no compilation errors, this is why I was getting this error. Everything started working as soon as I realized that I wasn't actually building the project before deploying :-/

Well, that's my story :-)

How do we change the URL of a working GitLab install?

Do not forget to clear the cache after updating the external_url param in /etc/gitlab/gitlab.rb, otherwise your existing project clone URLs will still be showing your old host name.

A simple 3 step process to change the hostname is as follows

  • update the external_url param in /etc/gitlab/gitlab.rb
  • sudo gitlab-ctl reconfigure
  • sudo gitlab-ctl restart
  • sudo gitlab-rake cache:clear


How to get Android GPS location

Worked a day for this project. It maybe useful for u. I compressed and combined both Network and GPS. Plug and play directly in (There are some DIY function for display result)

////////// LOCATION PACK //////////
//  locationManager: (LocationManager) for getting LOCATION_SERVICE
//  osLocation: (Location) getting location data via standard method
//  dataLocation: class type storage locztion data
//    x,y: (Double) Longtitude, Latitude
//  location: (dataLocation) variable contain absolute location info. Autoupdate after run locationStart();
//  AutoLocation: class help getting provider info
//  tmLocation: (Timer) for running update location over time
//  LocationStart(int interval): start getting location data with setting interval time cycle in milisecond
//  LocationStart(): LocationStart(500)
//  LocationStop(): stop getting location data
//  EX:
//    LocationStart(); cycleF(new Runnable() {public void run(){bodyM.text("LOCATION \nLatitude: " + location.y+ "\nLongitude: " + location.x).show();}},500);

LocationManager locationManager;
Location osLocation;
public class dataLocation {double x,y;}
dataLocation location=new dataLocation();
public class AutoLocation extends Activity implements LocationListener {
    @Override public void onLocationChanged(Location p1){}
    @Override public void onStatusChanged(String p1, int p2, Bundle p3){}
    @Override public void onProviderEnabled(String p1){}
    @Override public void onProviderDisabled(String p1){}
    public Location getLocation(String provider) {
        if (locationManager.isProviderEnabled(provider)) {
            if (locationManager != null) {
                osLocation = locationManager.getLastKnownLocation(provider);
                return osLocation;
        return null;
Timer tmLocation=new Timer();
public void LocationStart(int interval){
    locationManager = (LocationManager) this.getSystemService(LOCATION_SERVICE);
    final AutoLocation autoLocation = new AutoLocation();
    tmLocation=cycleF(new Runnable() {public void run(){ 
                Location nwLocation = autoLocation.getLocation(LocationManager.NETWORK_PROVIDER);
                if (nwLocation != null) {
                    location.y = nwLocation.getLatitude();
                    location.x = nwLocation.getLongitude();
                } else {
                    //bodym.text("NETWORK_LOCATION is loading...").show();
                Location gpsLocation = autoLocation.getLocation(LocationManager.GPS_PROVIDER);
                if (gpsLocation != null) {
                    location.y = gpsLocation.getLatitude();
                    location.x = gpsLocation.getLongitude();    
                } else {
                    //bodym.text("GPS_LOCATION is loading...").show();
            }}, interval);
public void LocationStart(){LocationStart(500);};
public void LocationStop(){stopCycleF(tmLocation);}

///END//// LOCATION PACK //////////

////////// RUNTIME //////////
// Need library:
//  import java.util.*;
// delayF(r,d): execute runnable r after d millisecond
//   Halt by execute the return: final Runnable rn=delayF(...); (new Handler()).post(rn);
// cycleF(r,i): execute r repeatedly with i millisecond each cycle
// stopCycleF(t): halt execute cycleF via the Timer return of cycleF
// EX:
//   delayF(new Runnable(){public void run(){ sig("Hi"); }},2000);
//   final Runnable rn=delayF(new Runnable(){public void run(){ sig("Hi"); }},3000);
//     delayF(new Runnable(){public void run(){ (new Handler()).post(rn);sig("Hello"); }},1000);
//   final Timer tm=cycleF(new Runnable() {public void run(){ sig("Neverend"); }}, 1000);
//     delayF(new Runnable(){public void run(){ stopCycleF(tm);sig("Ended"); }},7000);
public static Runnable delayF(final Runnable r, long delay) {
    final Handler h = new Handler();
    h.postDelayed(r, delay);
    return new Runnable(){
        public void run(){h.removeCallbacks(r);}
public static Timer cycleF(final Runnable r, long interval) {
    final Timer t=new Timer();
    final Handler h = new Handler();
    t.scheduleAtFixedRate(new TimerTask() {
            public void run() {;}
        }, interval, interval);
    return t;
public void stopCycleF(Timer t){t.cancel();t.purge();}
public boolean serviceRunning(Class<?> serviceClass) {
    ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
        if (serviceClass.getName().equals(service.service.getClassName())) {
            return true;
    return false;
///END//// RUNTIME //////////

Convert text into number in MySQL query

You can use SUBSTRING and CONVERT:

SELECT stuff
FROM table
WHERE conditions

Where name_column is the column with the "name-" values. The SUBSTRING removes everything up before the sixth character (i.e. the "name-" prefix) and then the CONVERT converts the left over to a real integer.

UPDATE: Given the changing circumstances in the comments (i.e. the prefix can be anything), you'll have to throw a LOCATE in the mix:

ORDER BY CONVERT(SUBSTRING(name_column, LOCATE('-', name_column) + 1), SIGNED INTEGER);

This of course assumes that the non-numeric prefix doesn't have any hyphens in it but the relevant comment says that:

name can be any sequence of letters

so that should be a safe assumption.

Redirect Windows cmd stdout and stderr to a single file

Background info from MSKB

While the accepted answer to this question is correct, it really doesn't do much to explain why it works, and since the syntax is not immediately clear I did a quick google to find out what was actually going on. In the hopes that this information is helpful to others, I'm posting it here.

Taken from MS Support KB 110930.

From MSKB110930

Redirecting Error Messages from Command Prompt: STDERR/STDOUT


When redirecting output from an application using the '>' symbol, error messages still print to the screen. This is because error messages are often sent to the Standard Error stream instead of the Standard Out stream.

Output from a console (Command Prompt) application or command is often sent to two separate streams. The regular output is sent to Standard Out (STDOUT) and the error messages are sent to Standard Error (STDERR). When you redirect console output using the ">" symbol, you are only redirecting STDOUT. In order to redirect STDERR you have to specify '2>' for the redirection symbol. This selects the second output stream which is STDERR.


The command dir (where does not exist) will display the following output:

Volume in drive F is Candy Cane Volume Serial Number is 34EC-0876

File Not Found

If you redirect the output to the NUL device using dir > nul, you will still see the error message part of the output, like this:

File Not Found

To redirect (only) the error message to NUL, use the following command:

dir 2> nul

Or, you can redirect the output to one place, and the errors to another.

dir > output.msg 2> output.err

You can print the errors and standard output to a single file by using the "&1" command to redirect the output for STDERR to STDOUT and then sending the output from STDOUT to a file:

dir 1> output.msg 2>&1

makefiles - compile all c files at once

SRCS=$(wildcard *.c)


all: $(OBJS)

Change old commit message on Git

It says:

When you save and exit the editor, it will rewind you back to that last commit in that list and drop you on the command line with the following message:

$ git rebase -i HEAD~3
Stopped at 7482e0d... updated the gemspec to hopefully work better
You can amend the commit now, with

It does not mean:

type again git rebase -i HEAD~3

Try to not typing git rebase -i HEAD~3 when exiting the editor, and it should work fine.
(otherwise, in your particular situation, a git rebase -i --abort might be needed to reset everything and allow you to try again)

As Dave Vogt mentions in the comments, git rebase --continue is for going to the next task in the rebasing process, after you've amended the first commit.

Also, Gregg Lind mentions in his answer the reword command of git rebase:

By replacing the command "pick" with the command "edit", you can tell git rebase to stop after applying that commit, so that you can edit the files and/or the commit message, amend the commit, and continue rebasing.

If you just want to edit the commit message for a commit, replace the command "pick" with the command "reword", since Git1.6.6 (January 2010).

It does the same thing ‘edit’ does during an interactive rebase, except it only lets you edit the commit message without returning control to the shell. This is extremely useful.
Currently if you want to clean up your commit messages you have to:

$ git rebase -i next

Then set all the commits to ‘edit’. Then on each one:

# Change the message in your editor.
$ git commit --amend
$ git rebase --continue

Using ‘reword’ instead of ‘edit’ lets you skip the git-commit and git-rebase calls.

What's the difference between UTF-8 and UTF-8 without BOM?

UTF-8 without BOM has no BOM, which doesn't make it any better than UTF-8 with BOM, except when the consumer of the file needs to know (or would benefit from knowing) whether the file is UTF-8-encoded or not.

The BOM is usually useful to determine the endianness of the encoding, which is not required for most use cases.

Also, the BOM can be unnecessary noise/pain for those consumers that don't know or care about it, and can result in user confusion.

Show "Open File" Dialog

I agree John M has best answer to OP's question. Thought not explictly stated, the apparent purpose is to get a selected file name, whereas other answers return either counts or lists. I would add, however, that the msofiledialogfilepicker might be a better option in this case. ie:

Dim f As object
Set f = Application.FileDialog(msoFileDialogFilePicker)
dim varfile as variant
with f
    .allowmultiselect = false
     for each varfile in .selecteditems
        msgbox varfile
     next varfile
end with

Note: the value of varfile will remain the same since multiselect is false (only one item is ever selected). I used its value outside the loop with equal success. It's probably better practice to do it as John M did, however. Also, the folder picker can be used to get a selected folder. I always prefer late binding, but I think the object is native to the default access library, so it may not be necessary here

initialize a numpy array

I'd suggest defining shape first. Then iterate over it to insert values.

big_array= np.zeros(shape = ( 6, 2 ))
for it in range(6):
    big_array[it] = (it,it) # For example


array([[ 0.,  0.],
       [ 1.,  1.],
       [ 2.,  2.],
       [ 3.,  3.],
       [ 4.,  4.],
       [ 5.,  5.]])

How to increase an array's length

Example of Array length change method (with old data coping):

static int[] arrayLengthChange(int[] arr, int newLength) {
    int[] arrNew = new int[newLength];
    System.arraycopy(arr, 0, arrNew, 0, arr.length);
    return arrNew;