Programs & Examples On #Insight

Insight is a graphical front-end for GDB, the GNU Debugger, developed by RedHat. Its development has been stopped in July 2009 with the version 6.8 of GDB.

Error - Android resource linking failed (AAPT2 27.0.3 Daemon #0) just recently got update and maybe affect to plugin that use updated version in their dependencies. But if you cannot find in the dependencies (like if you use crosswalk plugin), just put this code in top of your code gradle plugin (no need to add on build.gradle).

configurations.all {
resolutionStrategy.force ''

Example location to put the code in crosswalk plugin here

Feel free to edit version of (DO NOT USE THE 28.0.0) because thats the problem

PackagesNotFoundError: The following packages are not available from current channels:

Conda itself provides a quite detailed guidance about installing non-conda packages. Details can be found here:

The basic idea is to use conda-forge. If it doesn't work, activate the environment and use pip.

find_spec_for_exe': can't find gem bundler (>= 0.a) (Gem::GemNotFoundException)

My problem was I'm using RVM and had the wrong Ruby version activated...

Hope this helps at least one person

How to generate components in a specific folder with Angular CLI?

Quick, Simple and Error free method

i.e. You want to create a component in a app/common folder as shown in the image given below, then follow these steps

  1. Right click on the folder in which you want to create component.
  2. Select option Open in Integrated Terminal or Open in Command Prompt.
  3. In new terminal (you'll see your selected path), then type ng g c my-component

Also you can check this process through this image enter image description here

Jest spyOn function called

In your test code your are trying to pass App to the spyOn function, but spyOn will only work with objects, not classes. Generally you need to use one of two approaches here:

1) Where the click handler calls a function passed as a prop, e.g.

class App extends Component {

  myClickFunc = () => {
      console.log('clickity clickcty');
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        <p className="App-intro" onClick={this.myClickFunc}>
          To get started, edit <code>src/App.js</code> and save to reload.

You can now pass in a spy function as a prop to the component, and assert that it is called:

describe('my sweet test', () => {
 it('clicks it', () => {
    const spy = jest.fn();
    const app = shallow(<App someCallback={spy} />)
    const p = app.find('.App-intro')

2) Where the click handler sets some state on the component, e.g.

class App extends Component {
  state = {
      aProperty: 'first'

  myClickFunc = () => {
      console.log('clickity clickcty');
          aProperty: 'second'
  render() {
    return (
      <div className="App">
        <div className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h2>Welcome to React</h2>
        <p className="App-intro" onClick={this.myClickFunc}>
          To get started, edit <code>src/App.js</code> and save to reload.

You can now make assertions about the state of the component, i.e.

describe('my sweet test', () => {
 it('clicks it', () => {
    const app = shallow(<App />)
    const p = app.find('.App-intro')

Getting permission denied (public key) on gitlab

Step 1: Added a config file in ~/.ssh/config file which looks like

   User git
   IdentityFile ~/.ssh/id_rsa_gitlab
   TCPKeepAlive yes
   IdentitiesOnly yes

Step 2: Just clone the git repo WITHOUT sudo.

Deep-Learning Nan loss reasons

If you'd like to gather more information on the error and if the error occurs in the first few iterations, I suggest you run the experiment in CPU-only mode (no GPUs). The error message will be much more specific.


How do I access Configuration in any class in ASP.NET Core?

In ASP.NET Core, there are configuration providers for reading configurations from almost anywhere such as files e.g. JSON, INI or XML, environment variables, Azure key vault, command-line arguments, etc. and many more sources. I have written a step by step guide to show you how can you configure your application settings in various files such as JSON, INI or XML and how can you read those settings from your application code. I will also demonstrate how can you read application settings as custom .NET types (classes) and how can you use the built-in ASP.NET Core dependency injection to read your configuration settings in multiple classes, services or even projects available in your solution.

Read A Step by Step Guide for ASP.NET Core Configuration

Body of Http.DELETE request in Angular2

In Angular 5, I had to use the request method instead of delete to send a body. The documentation for the delete method does not include body, but it is included in the request method.

import { HttpClient } from '@angular/common/http';
import { HttpHeaders } from '@angular/common/http';

this.http.request('DELETE', url, {
    headers: new HttpHeaders({
        'Content-Type': 'application/json',
    body: { foo: bar }

What is the best way to access redux store outside a react component?

Export the store from the module you called createStore with. Then you are assured it will both be created and will not pollute the global window space.


const store = createStore(myReducer);
export store;


const store = createStore(myReducer);
export default store;


import {store} from './MyStore'

or if you used default

import store from './MyStore'

For Multiple Store Use Cases

If you need multiple instances of a store, export a factory function. I would recommend making it async (returning a promise).

async function getUserStore (userId) {
   // check if user store exists and return or create it.
export getUserStore

On the client (in an async block)

import {getUserStore} from './store'

const joeStore = await getUserStore('joe')

How to get rid of underline for Link component of React Router?

If someone is looking for material-ui's Link component. Just add the property underline and set it to none

<Link underline="none">...</Link>

What are the pros and cons of parquet format compared to other formats?

I think the main difference I can describe relates to record oriented vs. column oriented formats. Record oriented formats are what we're all used to -- text files, delimited formats like CSV, TSV. AVRO is slightly cooler than those because it can change schema over time, e.g. adding or removing columns from a record. Other tricks of various formats (especially including compression) involve whether a format can be split -- that is, can you read a block of records from anywhere in the dataset and still know it's schema? But here's more detail on columnar formats like Parquet.

Parquet, and other columnar formats handle a common Hadoop situation very efficiently. It is common to have tables (datasets) having many more columns than you would expect in a well-designed relational database -- a hundred or two hundred columns is not unusual. This is so because we often use Hadoop as a place to denormalize data from relational formats -- yes, you get lots of repeated values and many tables all flattened into a single one. But it becomes much easier to query since all the joins are worked out. There are other advantages such as retaining state-in-time data. So anyway it's common to have a boatload of columns in a table.

Let's say there are 132 columns, and some of them are really long text fields, each different column one following the other and use up maybe 10K per record.

While querying these tables is easy with SQL standpoint, it's common that you'll want to get some range of records based on only a few of those hundred-plus columns. For example, you might want all of the records in February and March for customers with sales > $500.

To do this in a row format the query would need to scan every record of the dataset. Read the first row, parse the record into fields (columns) and get the date and sales columns, include it in your result if it satisfies the condition. Repeat. If you have 10 years (120 months) of history, you're reading every single record just to find 2 of those months. Of course this is a great opportunity to use a partition on year and month, but even so, you're reading and parsing 10K of each record/row for those two months just to find whether the customer's sales are > $500.

In a columnar format, each column (field) of a record is stored with others of its kind, spread all over many different blocks on the disk -- columns for year together, columns for month together, columns for customer employee handbook (or other long text), and all the others that make those records so huge all in their own separate place on the disk, and of course columns for sales together. Well heck, date and months are numbers, and so are sales -- they are just a few bytes. Wouldn't it be great if we only had to read a few bytes for each record to determine which records matched our query? Columnar storage to the rescue!

Even without partitions, scanning the small fields needed to satisfy our query is super-fast -- they are all in order by record, and all the same size, so the disk seeks over much less data checking for included records. No need to read through that employee handbook and other long text fields -- just ignore them. So, by grouping columns with each other, instead of rows, you can almost always scan less data. Win!

But wait, it gets better. If your query only needed to know those values and a few more (let's say 10 of the 132 columns) and didn't care about that employee handbook column, once it had picked the right records to return, it would now only have to go back to the 10 columns it needed to render the results, ignoring the other 122 of the 132 in our dataset. Again, we skip a lot of reading.

(Note: for this reason, columnar formats are a lousy choice when doing straight transformations, for example, if you're joining all of two tables into one big(ger) result set that you're saving as a new table, the sources are going to get scanned completely anyway, so there's not a lot of benefit in read performance, and because columnar formats need to remember more about the where stuff is, they use more memory than a similar row format).

One more benefit of columnar: data is spread around. To get a single record, you can have 132 workers each read (and write) data from/to 132 different places on 132 blocks of data. Yay for parallelization!

And now for the clincher: compression algorithms work much better when it can find repeating patterns. You could compress AABBBBBBCCCCCCCCCCCCCCCC as 2A6B16C but ABCABCBCBCBCCCCCCCCCCCCCC wouldn't get as small (well, actually, in this case it would, but trust me :-) ). So once again, less reading. And writing too.

So we read a lot less data to answer common queries, it's potentially faster to read and write in parallel, and compression tends to work much better.

Columnar is great when your input side is large, and your output is a filtered subset: from big to little is great. Not as beneficial when the input and outputs are about the same.

But in our case, Impala took our old Hive queries that ran in 5, 10, 20 or 30 minutes, and finished most in a few seconds or a minute.

Hope this helps answer at least part of your question!

npm install error - unable to get local issuer certificate

In case you use yarn:

yarn config set strict-ssl false

REST API - file (ie images) processing - best practices

Your second solution is probably the most correct. You should use the HTTP spec and mimetypes the way they were intended and upload the file via multipart/form-data. As far as handling the relationships, I'd use this process (keeping in mind I know zero about your assumptions or system design):

  1. POST to /users to create the user entity.
  2. POST the image to /images, making sure to return a Location header to where the image can be retrieved per the HTTP spec.
  3. PATCH to /users/carPhoto and assign it the ID of the photo given in the Location header of step 2.

Error: Execution failed for task ':app:clean'. Unable to delete file

If you are using Android Studio 2.0 Beta, this issue might appear (more likely if you are working on NTFS filesystem) and it seems like the "Instant Run" is the culprit. Search for "Instant Run" in settings and uncheck the box.

I have filed an issue on the bug tracker.

Detecting user leaving page with react-router

For react-router 2.4.0+

NOTE: It is advisable to migrate all your code to the latest react-router to get all the new goodies.

As recommended in the react-router documentation:

One should use the withRouter higher order component:

We think this new HoC is nicer and easier, and will be using it in documentation and examples, but it is not a hard requirement to switch.

As an ES6 example from the documentation:

import React from 'react'
import { withRouter } from 'react-router'

const Page = React.createClass({

  componentDidMount() {
    this.props.router.setRouteLeaveHook(this.props.route, () => {
      if (this.state.unsaved)
        return 'You have unsaved information, are you sure you want to leave this page?'

  render() {
    return <div>Stuff</div>


export default withRouter(Page)

How to load CSS Asynchronously

2020 Update

The simple answer (full browser support):

<link rel="stylesheet" href="style.css" media="print" onload="'all'">

The documented answer (with optional preloading and script-disabled fallback):

 <!-- Optional, if we want the stylesheet to get preloaded. Note that this line causes stylesheet to get downloaded, but not applied to the page. Use strategically — while preloading will push this resource up the priority list, it may cause more important resources to be pushed down the priority list. This may not be the desired effect for non-critical CSS, depending on other resources your app needs. -->
 <link rel="preload" href="style.css" as="style">

 <!-- Media type (print) doesn't match the current environment, so browser decides it's not that important and loads the stylesheet asynchronously (without delaying page rendering). On load, we change media type so that the stylesheet gets applied to screens. -->
 <link rel="stylesheet" href="style.css" media="print" onload="'all'">

 <!-- Fallback that only gets inserted when JavaScript is disabled, in which case we can't load CSS asynchronously. -->
 <noscript><link rel="stylesheet" href="style.css"></noscript>

Preloading and async combined:

If you need preloaded and async CSS, this solution simply combines two lines from the documented answer above, making it slightly cleaner. But this won't work in Firefox until they support the preload keyword. And again, as detailed in the documented answer above, preloading may not actually be beneficial.

<link href="style.css" rel="preload" as="style" onload="this.rel='stylesheet'">
<noscript><link rel="stylesheet" href="style.css"></noscript>

Additional considerations:

Note that, in general, if you're going to load CSS asynchronously, it's generally recommended that you inline critical CSS, since CSS is a render-blocking resource for a reason.

Credit to filament group for their many async CSS solutions.

PageSpeed Insights 99/100 because of Google Analytics - How can I cache GA?

In the Google docs, they've identified a pagespeed filter that will load the script asynchronously:

ModPagespeedEnableFilters make_google_analytics_async

You can find the documentation here:

One thing to highlight is that the filter is considered high risk. From the docs:

The make_google_analytics_async filter is experimental and has not had extensive real-world testing. One case where a rewrite would cause errors is if the filter misses calls to Google Analytics methods that return values. If such methods are found, the rewrite is skipped. However, the disqualifying methods will be missed if they come before the load, are in attributes such as "onclick", or if they are in external resources. Those cases are expected to be rare.

Google Chrome forcing download of "f.txt" file

This can occur on android too not just computers. Was browsing using Kiwi when the site I was on began to endlessly redirect so I cut net access to close it out and noticed my phone had DL'd something f.txt in my downloaded files.

Deleted it and didn't open.

Touch move getting stuck Ignored attempt to cancel a touchmove

I know this is an old post but I had a lot of issues trying to solve this and I finally did so I wanted to share.

My issue was that I was adding an event listener within the ontouchstart and removing it in the ontouchend functions - something like this

function onTouchStart() {
  window.addEventListener("touchmove", handleTouchMove, {
    passive: false

function onTouchEnd() {
  window.removeEventListener("touchmove", handleTouchMove, {
    passive: true

function handleTouchMove(e) {

For some reason adding it removing it like this was causing this issue of the event randomly not being cancelable. So to solve this I kept the listener active and toggled a boolean on whether or not it should prevent the event - something like this:

let stopScrolling = false;

window.addEventListener("touchmove", handleTouchMove, {
  passive: false

function handleTouchMove(e) {
  if (!stopScrolling) {

function onTouchStart() {
  stopScrolling = true;

function onTouchEnd() {
  stopScrolling = false;

I was actually using React so my solution involved setting state, but I've simplified it for a more generic solution. Hopefully this helps someone!

File size exceeds configured limit (2560000), code insight features not available

Windows default install location for Webstorm:

C:\Program Files\JetBrains\WebStorm 2019.1.3\bin\

I went x4 default for intellisense and x5 for file size

(my business workstation is a beast though: 8th gen i7, 32Gb RAM, NVMe PCIE3.0x4 SDD, gloat, etc, gloat, etc)

# Maximum file size (kilobytes) IDE should provide code assistance for.
# The larger file is the slower its editor works and higher overall system memory requirements are
# if code assistance is enabled. Remove this property or set to very large number if you need
# code assistance for any files available regardless their size.

    # Maximum file size (kilobytes) IDE is able to open.


Peak signal detection in realtime timeseries data

One approach is to detect peaks based on the following observation:

  • Time t is a peak if (y(t) > y(t-1)) && (y(t) > y(t+1))

It avoids false positives by waiting until the uptrend is over. It is not exactly "real-time" in the sense that it will miss the peak by one dt. sensitivity can be controlled by requiring a margin for comparison. There is a trade off between noisy detection and time delay of detection. You can enrich the model by adding more parameters:

  • peak if (y(t) - y(t-dt) > m) && (y(t) - y(t+dt) > m)

where dt and m are parameters to control sensitivity vs time-delay

This is what you get with the mentioned algorithm: enter image description here

here is the code to reproduce the plot in python:

import numpy as np
import matplotlib.pyplot as plt
input = np.array([ 1. ,  1. ,  1. ,  1. ,  1. ,  1. ,  1. ,  1.1,  1. ,  0.8,  0.9,
    1. ,  1.2,  0.9,  1. ,  1. ,  1.1,  1.2,  1. ,  1.5,  1. ,  3. ,
    2. ,  5. ,  3. ,  2. ,  1. ,  1. ,  1. ,  0.9,  1. ,  1. ,  3. ,
    2.6,  4. ,  3. ,  3.2,  2. ,  1. ,  1. ,  1. ,  1. ,  1. ])
signal = (input > np.roll(input,1)) & (input > np.roll(input,-1))
plt.plot(signal.nonzero()[0], input[signal], 'ro')

By setting m = 0.5, you can get a cleaner signal with only one false positive: enter image description here

How to download a file from my server using SSH (using PuTTY on Windows)

You can use the WinSPC program. Its access to any server is pretty easy. The program gives its guide too. I hope it's helpfull.

git: diff between file in local repo and origin

Full answer to the original question that was talking about a possible different path on local and remote is below

  1. git fetch origin
  2. git diff master -- [local-path] origin/master -- [remote-path]

Assuming the local path is docs/file1.txt and remote path is docs2/file1.txt, use git diff master -- docs/file1.txt origin/master -- docs2/file1.txt

This is adapted from GitHub help page here and Code-Apprentice answer above

Why is this error, 'Sequence contains no elements', happening?

Check again. Use debugger if must. My guess is that for some item in userResponseDetails this query finds no elements:

.Where(y => y.ResponseId.Equals(item.ResponseId))

so you can't call


on it. Maybe try


if it solves the issue.

Do NOT return NULL value! This is purely so that you can see and diagnose where problem is. Handle these cases properly.

The program can't start because MSVCR110.dll is missing from your computer

I was getting a similar issue from the Apache Lounge 32 bit version. After downloading the 64 bit version, the issue was resolved.

Here is an excellent video explain the steps involved:

Bootstrap 3 Slide in Menu / Navbar on Mobile

Bootstrap 4

Create a responsive navbar sidebar "drawer" in Bootstrap 4?
Bootstrap horizontal menu collapse to sidemenu

Bootstrap 3

I think what you're looking for is generally known as an "off-canvas" layout. Here is the standard off-canvas example from the official Bootstrap docs:

The "official" example uses a right-side sidebar the toggle off and on separately from the top navbar menu. I also found these off-canvas variations that slide in from the left and may be closer to what you're looking for..

Laravel Eloquent get results grouped by days

Warning: untested code.

$dailyData = DB::table('page_views')
    ->select('created_at', DB::raw('count(*) as views'))

JavaFX "Location is required." even though it is in the same package

I have found all of the above solutions work just fine because they trigger your IDE to rebuild the project. No magic involved.

The "real" solution for this issue is that you should just ditch your previous build directory.

  • If you are using Maven, just delete the target folder (or do a mvn clean)!
  • If you're using ANT, delete that respective folder (I think it's called out)!
  • If you're using Gradle, delete the build folder!

How to connect to mysql with laravel?

In Laravel 5, there is a .env file,

It looks like





Edit that .env There is .env.sample is there , try to create from that if no such .env file found.

Insert Data Into Temp Table with Query

Fastest way to do this is using "SELECT INTO" command e.g.

SELECT * INTO #TempTableName

This will create a new table, you don't have to create it in advance.

Can you split a stream into two streams?

How about:

Supplier<Stream<Integer>> randomIntsStreamSupplier =
    () -> (new Random()).ints(0, 2).boxed();

Stream<Integer> tails =
Stream<Integer> heads =

Bootstrap 3 : Vertically Center Navigation Links when Logo Increasing The Height of Navbar

Use the Bootstrap Customizer to generate a version of Bootstrap that has a taller navbar. The value you want to change is @navbar-height in the Navbar section.

Inspect your current implementation to see how tall your navbar is with the 50px brand image, and use that calculated height in the Customizer.

Eclipse gives “Java was started but returned exit code 13”

I could resolve this issue by changing JDK1.8 64bit version to JDK 1.8 32bit(x86) version

Name does not exist in the current context


This is the phyiscal file -> CodeFile="Jobs.aspx.cs"

This is the class which handles the events of the page -> Inherits="Members_Jobs"


This is the partial class which manages the page events -> public partial class Members_Jobs : System.Web.UI.Page

The other part of the partial class should be -> public partial class Members_Jobs this is usually the designer file.

you dont need to have partial classes and could declare your controls all in 1 class and not have a designer file.

EDIT 27/09/2013 11:37

if you are still having issues with this I would do as Bharadwaj suggested and delete the designer file. You can then right-click on the page, in the solution explorer, and there is an option, something like "Convert to Web Application", which will regenerate your designer file

"Data too long for column" - why?

I try to create a table with a field as 200 characters and I've added two rows with early 160 characters and it's OK. Are you sure your rows are less than 200 characters?

Show SqlFiddle

"Eliminate render-blocking CSS in above-the-fold content"

Consider using a package to automatically generate inline styles from your css files. A good one is Grunt Critical or Critical css for Laravel.

How to extract or unpack an .ab file (Android Backup file)

As per you can run a one line command in Linux to add in an appropriate tar header to extract it.

( printf "\x1f\x8b\x08\x00\x00\x00\x00\x00" ; tail -c +25 backup.ab ) | tar xfvz -

Replace backup.ab with the path to your file.

Is it bad practice to use break to exit a loop in Java?

No, it is not a bad practice to break out of a loop when if certain desired condition is reached(like a match is found). Many times, you may want to stop iterations because you have already achieved what you want, and there is no point iterating further. But, be careful to make sure you are not accidentally missing something or breaking out when not required.

This can also add to performance improvement if you break the loop, instead of iterating over thousands of records even if the purpose of the loop is complete(i.e. may be to match required record is already done).

Example :

for (int j = 0; j < type.size(); j++) {
        if (condition) {
            // do stuff after which you want 

            break; // stop further iteration


How can I enable Assembly binding logging?

  1. Create a new Application Pool

  2. Go to the Advanced Settings of this application pool

  3. Set the Enable 32-Bit Application to True

  4. Point your web application to use this new Pool

Screenshot (IIS-ApplicationPool)

Python readlines() usage and efficient practice for reading

The short version is: The efficient way to use readlines() is to not use it. Ever.

I read some doc notes on readlines(), where people has claimed that this readlines() reads whole file content into memory and hence generally consumes more memory compared to readline() or read().

The documentation for readlines() explicitly guarantees that it reads the whole file into memory, and parses it into lines, and builds a list full of strings out of those lines.

But the documentation for read() likewise guarantees that it reads the whole file into memory, and builds a string, so that doesn't help.

On top of using more memory, this also means you can't do any work until the whole thing is read. If you alternate reading and processing in even the most naive way, you will benefit from at least some pipelining (thanks to the OS disk cache, DMA, CPU pipeline, etc.), so you will be working on one batch while the next batch is being read. But if you force the computer to read the whole file in, then parse the whole file, then run your code, you only get one region of overlapping work for the entire file, instead of one region of overlapping work per read.

You can work around this in three ways:

  1. Write a loop around readlines(sizehint), read(size), or readline().
  2. Just use the file as a lazy iterator without calling any of these.
  3. mmap the file, which allows you to treat it as a giant string without first reading it in.

For example, this has to read all of foo at once:

with open('foo') as f:
    lines = f.readlines()
    for line in lines:

But this only reads about 8K at a time:

with open('foo') as f:
    while True:
        lines = f.readlines(8192)
        if not lines:
        for line in lines:

And this only reads one line at a time—although Python is allowed to (and will) pick a nice buffer size to make things faster.

with open('foo') as f:
    while True:
        line = f.readline()
        if not line:

And this will do the exact same thing as the previous:

with open('foo') as f:
    for line in f:


but should the garbage collector automatically clear that loaded content from memory at the end of my loop, hence at any instant my memory should have only the contents of my currently processed file right ?

Python doesn't make any such guarantees about garbage collection.

The CPython implementation happens to use refcounting for GC, which means that in your code, as soon as file_content gets rebound or goes away, the giant list of strings, and all of the strings within it, will be freed to the freelist, meaning the same memory can be reused again for your next pass.

However, all those allocations, copies, and deallocations aren't free—it's much faster to not do them than to do them.

On top of that, having your strings scattered across a large swath of memory instead of reusing the same small chunk of memory over and over hurts your cache behavior.

Plus, while the memory usage may be constant (or, rather, linear in the size of your largest file, rather than in the sum of your file sizes), that rush of mallocs to expand it the first time will be one of the slowest things you do (which also makes it much harder to do performance comparisons).

Putting it all together, here's how I'd write your program:

for filename in os.listdir(input_dir):
    with open(filename, 'rb') as f:
        if filename.endswith(".gz"):
            f =
        words = (line.split(delimiter) for line in f)
        ... my logic ...  

Or, maybe:

for filename in os.listdir(input_dir):
    if filename.endswith(".gz"):
        f =, 'rb')
        f = open(filename, 'rb')
    with contextlib.closing(f):
        words = (line.split(delimiter) for line in f)
        ... my logic ...

Disable firefox same origin policy

There's a Firefox extension that adds the CORS headers to any HTTP response working on the latest Firefox (build 36.0.1) released March 5, 2015. I tested it and it's working on both Windows 7 and Mavericks. I'll guide you throught the steps to get it working.

1) Getting the extension

You can either download the xpi from here (author builds) or from here (mirror, may not be updated).

Or download the files from GitHub. Now it's also on Firefox Marketplace: Download here. In this case, the addon is installed after you click install and you can skip to step 4.

If you downloaded the xpi you can jump to step 3. If you downloaded the zip from GitHub, go to step 2.

2) Building the xpi

You need to extract the zip, get inside the "cors-everywhere-firefox-addon-master" folder, select all the items and zip them. Then, rename the created zip as *.xpi

Note: If you are using the OS X gui, it may create some hidden files, so you 'd be better using the command line.

3) Installing the xpi

You can just drag and drop the xpi to firefox, or go to: "about:addons", click on the cog on the top right corner and select "install add on from file", then select you .xpi file. Now, restart firefox.

4) Getting it to work

Now, the extension won't be working by default. You need to drag the extension icon to the extension bar, but don't worry. There are pictures!

  • Click on the Firefox Menu
  • Click on Customise


  • Drag CorsE to the bar
  • Now, click on the icon, when it's green the CORS headers will be added to any HTTP response


5) Testing if it's working


$.get( "", function( data ) {
  console.log (data);


xmlhttp=new XMLHttpRequest();

xmlhttp.onreadystatechange = function() {
    if (xmlhttp.readyState == 4) {

6) Final considerations

Note that https to http is not allowed.

There may be a way around it, but it's behind the scope of the question.

Registry Key '...' has value '1.7', but '1.6' is required. Java 1.7 is Installed and the Registry is Pointing to it

The jar was compiled to be 1.6 compliant. That is why you get this error. Two resolutions:
1) Use Java 1.6


2) Recompile the jar to be compliant for your environment 1.7

Are there any style options for the HTML5 Date picker?

found this on Zurb's github

In case you want to do some more custom styling. Here's all the default CSS for webkit rendering of the date components.

input[type="date"] {
     -webkit-align-items: center;
     display: -webkit-inline-flex;
     font-family: monospace;
     overflow: hidden;
     padding: 0;
     -webkit-padding-start: 1px;

input::-webkit-datetime-edit {
    -webkit-flex: 1;
    -webkit-user-modify: read-only !important;
    display: inline-block;
    min-width: 0;
    overflow: hidden;

input::-webkit-datetime-edit-fields-wrapper {
    -webkit-user-modify: read-only !important;
    display: inline-block;
    padding: 1px 0;
    white-space: pre;

In Angular, how to redirect with $location.path as $ success callback

Instead of using success, I change it to then and it works.

here is the code:

lgrg.controller('login', function($scope, $window, $http) {
    $scope.loginUser = {};

    $scope.submitForm = function() {
        $scope.errorInfo = null

            method  : 'POST',
            url     : '/login',
            headers : {'Content-Type': 'application/json'}
            data: $scope.loginUser
        }).then(function(data) {
            if (!data.status) {
                $scope.errorInfo =
            } else {
                //page jump
                $window.location.href = '/admin';

Eclipse Workspaces: What for and why?

The whole point of a workspace is to group a set of related projects together that usually make up an application. The workspace framework comes down to the eclipse.core.resources plugin and it naturally by design makes sense.

Projects have natures, builders are attached to specific projects and as you change resources in one project you can see in real time compile or other issues in projects that are in the same workspace. So the strategy I suggest is have different workspaces for different projects you work on but without a workspace in eclipse there would be no concept of a collection of projects and configurations and after all it's an IDE tool.

If that does not make sense ask how Net Beans or Visual Studio addresses this? It's the same theme. Maven is a good example, checking out a group of related maven projects into a workspace lets you develop and see errors in real time. If not a workspace what else would you suggest? An RCP application can be a different beast depending on what its used for but in the true IDE sense I don't know what would be a better solution than a workspace or context of projects. Just my thoughts. - Duncan

Entity Framework Migrations renaming tables and columns

In EF Core, I use the following statements to rename tables and columns:

As for renaming tables:

    protected override void Up(MigrationBuilder migrationBuilder)
        migrationBuilder.RenameTable(name: "OldTableName", schema: "dbo", newName: "NewTableName", newSchema: "dbo");

    protected override void Down(MigrationBuilder migrationBuilder)
        migrationBuilder.RenameTable(name: "NewTableName", schema: "dbo", newName: "OldTableName", newSchema: "dbo");

As for renaming columns:

    protected override void Up(MigrationBuilder migrationBuilder)
        migrationBuilder.RenameColumn(name: "OldColumnName", table: "TableName", newName: "NewColumnName", schema: "dbo");

    protected override void Down(MigrationBuilder migrationBuilder)
        migrationBuilder.RenameColumn(name: "NewColumnName", table: "TableName", newName: "OldColumnName", schema: "dbo");

What is Cache-Control: private?

The Expires entity-header field gives the date/time after which the response is considered stale.The Cache-control:maxage field gives the age value (in seconds) bigger than which response is consider stale.

Althought above header field give a mechanism to client to decide whether to send request to the server. In some condition, the client send a request to sever and the age value of response is bigger then the maxage value ,dose it means server needs to send the resource to client? Maybe the resource never changed.

In order to resolve this problem, HTTP1.1 gives last-modifided head. The server gives the last modified date of the response to client. When the client need this resource, it will send If-Modified-Since head field to server. If this date is before the modified date of the resouce, the server will sends the resource to client and gives 200 code.Otherwise,it will returns 304 code to client and this means client can use the resource it cached.

Creating a search form in PHP to search a database?

You're getting errors 'table liam does not exist' because the table's name is Liam which is not the same as liam. MySQL table names are case sensitive.

How to JUnit test that two List<E> contain the same elements in the same order?

Why not simply use List#equals?

assertEquals(argumentComponents, imapPathComponents);

Contract of List#equals:

two lists are defined to be equal if they contain the same elements in the same order.

PostgreSQL error 'Could not connect to server: No such file or directory'

for me command rm /usr/local/var/postgres/ didn't work cause I installed a specific version of postgresql with homebrew.

the right command is rm /usr/local/var/postgres@10/

then brew services restart postgresql@10.

Find Active Tab using jQuery and Twitter Bootstrap

First of all you need to remove the data-toggle attribute. We will use some JQuery, so make sure you include it.

  <ul class='nav nav-tabs'>
    <li class='active'><a href='#home'>Home</a></li>
    <li><a href='#menu1'>Menu 1</a></li>
    <li><a href='#menu2'>Menu 2</a></li>
    <li><a href='#menu3'>Menu 3</a></li>

  <div class='tab-content'>
    <div id='home' class='tab-pane fade in active'>
    <div id='menu1' class='tab-pane fade'>
      <h3>Menu 1</h3>
    <div id='menu2' class='tab-pane fade'>
      <h3>Menu 2</h3>
    <div id='menu3' class='tab-pane fade'>
      <h3>Menu 3</h3>

// Handling data-toggle manually
    $('.nav-tabs a').click(function(){
// The on tab shown event
    $('.nav-tabs a').on('', function (e) {
        alert('Hello from the other siiiiiide!');
        var current_tab =;
        var previous_tab = e.relatedTarget;

Python 3 turn range to a list

in Python 3.x, the range() function got its own type. so in this case you must use iterator


Parsing JSON array with PHP foreach

$user->data is an array of objects. Each element in the array has a name and value property (as well as others).

Try putting the 2nd foreach inside the 1st.

foreach($user->data as $mydata)
    echo $mydata->name . "\n";
    foreach($mydata->values as $values)
        echo $values->value . "\n";

X-Frame-Options: ALLOW-FROM in firefox and chrome

For Chrome, instead of

response.AppendHeader("X-Frame-Options", "ALLOW-FROM " + host);

you need to add Content-Security-Policy

string selfAuth = System.Web.HttpContext.Current.Request.Url.Authority;
string refAuth = System.Web.HttpContext.Current.Request.UrlReferrer.Authority;
response.AppendHeader("Content-Security-Policy", "default-src 'self' 'unsafe-inline' 'unsafe-eval' data: * " + selfAuth + " " + refAuth);

to the HTTP-response-headers.
Note that this assumes you checked on the server whether or not refAuth is allowed.
And also, note that you need to do browser-detection in order to avoid adding the allow-from header for Chrome (outputs error on console).

For details, see my answer here.

I need to learn Web Services in Java. What are the different types in it?

Q1) Here are couple things to read or google more :

Main differences between SOAP and RESTful web services in java

It's up to you what do you want to learn first. I'd recommend you take a look at the CXF framework. You can build both rest/soap services.

Q2) Here are couple of good tutorials for soap (I had them bookmarked) :

Best way to learn is not just reading tutorials. But you would first go trough tutorials to get a basic idea so you can see that you're able to produce something(or not) and that would get you motivated.

SO is great way to learn particular technology (or more), people ask lot of wierd questions, and there are ever weirder answers. But overall you'll learn about ways to solve issues on other way. Maybe you didn't know of that way, maybe you couldn't thought of it by yourself.

Subscribe to couple of tags that are interesting to you and be persistent, ask good questions and try to give good answers and I guarantee you that you'll learn this as time passes (if you're persistent that is).

Q3) You will have to answer this one yourself. First by deciding what you're going to build, after all you will need to think of some mini project or something and take it from there.

If you decide to use CXF as your framework for building either REST/SOAP services I'd recommend you look up this book Apache CXF Web Service Development. It's fantastic, not hard to read and not too big either (win win).

Changing the position of Bootstrap popovers based on the popover's X position in relation to window edge?

I just noticed that the placement option could either be a string or a function returning a string that makes the calculation each time you click on a popover-able link.

This makes it real easy to replicate what you did without the initial $.each function:

var options = {
    placement: function (context, source) {
        var position = $(source).position();

        if (position.left > 515) {
            return "left";

        if (position.left < 515) {
            return "right";

        if ( < 110){
            return "bottom";

        return "top";
    , trigger: "click"

C# : Passing a Generic Object

It doesn't compile because T could be anything, and not everything will have the myvar field.

You could make myvar a property on ITest:

public ITest
    string myvar{get;}

and implement it on the classes as a property:

public class MyClass1 : ITest
    public string myvar{ get { return "hello 1"; } }

and then put a generic constraint on your method:

public void PrintGeneric<T>(T test) where T : ITest
    Console.WriteLine("Generic : " + test.myvar);

but in that case to be honest you are better off just passing in an ITest:

public void PrintGeneric(ITest test)
    Console.WriteLine("Generic : " + test.myvar);

receiving error: 'Error: SSL Error: SELF_SIGNED_CERT_IN_CHAIN' while using npm

As of February 27, 2014, npm no longer supports its self-signed certificates. The following options, as recommended by npm, is to do one of the following:

Upgrade your version of npm

npm install npm -g --ca=""

-- OR --

Tell your current version of npm to use known registrars

npm config set ca ""

Update: npm has posted More help with SELF_SIGNED_CERT_IN_CHAIN and npm with more solutions particular to different environments

You may or may not need to prepend sudo to the recommendations.

Other options

It seems that people are having issues using npm's recommendations, so here are some other potential solutions.

Upgrade Node itself
Receiving this error may suggest you have an older version of node, which naturally comes with an older version of npm. One solution is to upgrade your version of Node. This is likely the best option as it brings you up to date and fixes existing bugs and vulnerabilities.

The process here depends on how you've installed Node, your operating system, and otherwise.

Update npm
Being that you probably got here while trying to install a package, it is possible that npm install npm -g might fail with the same error. If this is the case, use update instead. As suggested by Nisanth Sojan:

npm update npm -g

Update npm alternative
One way around the underlying issue is to use known registrars, install, and then stop using known registrars. As suggested by jnylen:

npm config set ca ""
npm install npm -g
npm config delete ca

How do I tell Python to convert integers into words

Use pynum2word module that can be found at sourceforge

>>> import num2word
>>> num2word.to_card(15)
>>> num2word.to_card(55)
>>> num2word.to_card(1555)
'one thousand, five hundred and fifty-five'

Why are elementwise additions much faster in separate loops than in a combined loop?

The second loop involves a lot less cache activity, so it's easier for the processor to keep up with the memory demands.

iOS Launching Settings -> Restrictions URL Scheme

As of iOS8 you can open the built-in Settings app with:

NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
if ([[UIApplication sharedApplication] canOpenURL:url]) {
   [[UIApplication sharedApplication] openURL:url];

The actual URL string is @"app-settings:". I tried appending different sections to the string ("Bluetooth", "GENERAL", etc.) but seems only linking to the main Settings screen works. Post a reply if you find out otherwise.

When to use cla(), clf() or close() for clearing a plot in matplotlib?

plt.cla() means clear current axis

plt.clf() means clear current figure

also, there's plt.gca() (get current axis) and plt.gcf() (get current figure)

Read more here: Matplotlib, Pyplot, Pylab etc: What's the difference between these and when to use each?

JavaScript Array Push key value

You have to use bracket notation:

var obj = {};
obj[a[i]] = 0;

The result will be:

x = [{left: 0}, {top: 0}];

Maybe instead of an array of objects, you just want one object with two properties:

var x = {};


x[a[i]] = 0;

This will result in x = {left: 0, top: 0}.

Redis: Show database size/size for keys

I usually prefer the key sampling method to troubleshoot such scenarios.

redis-cli -p 6379 -n db_number --bigkeys


redis-cli -p 6370 -n 0 --bigkeys

Why can't I find SQL Server Management Studio after installation?

Generally if the installation went smoothly, it will create the desktop icons/folders. Maybe check the installation summary log to see if there's any underlying errors.

It should be located C:\Program Files\Microsoft SQL Server\100\Setup Bootstrap\Log(date stamp)\

JSON Post with Customized HTTPHeader Field

I tried as you mentioned, but only first parameter is going through and rest all are appearing in the server as undefined. I am passing JSONWebToken as part of header.

    url: 'api/outletadd',
    type: 'post',
    data: { outletname:outletname , addressA:addressA , addressB:addressB, city:city , postcode:postcode , state:state , country:country , menuid:menuid },
    headers: {
        authorization: storedJWT
    dataType: 'json',
    success: function (data){
        alert("Outlet Created");
    error: function (data){
        alert("Outlet Creation Failed, please try again.");        


Reading content from URL with Node.js


const getScript = (url) => {
    return new Promise((resolve, reject) => {
        const http      = require('http'),
              https     = require('https');

        let client = http;

        if (url.toString().indexOf("https") === 0) {
            client = https;

        client.get(url, (resp) => {
            let data = '';

            // A chunk of data has been recieved.
            resp.on('data', (chunk) => {
                data += chunk;

            // The whole response has been received. Print out the result.
            resp.on('end', () => {

        }).on("error", (err) => {

(async (url) => {
    console.log(await getScript(url));

MySQL trigger if condition exists

I think you mean to update it back to the OLD password, when the NEW one is not supplied.



      IF (NEW.password IS NULL OR NEW.password = '') THEN
            SET NEW.password = OLD.password;
            SET NEW.password = Password(NEW.Password);
      END IF;


However, this means a user can never blank out a password.

If the password field (already encrypted) is being sent back in the update to mySQL, then it will not be null or blank, and MySQL will attempt to redo the Password() function on it. To detect this, use this code instead


      IF (NEW.password IS NULL OR NEW.password = '' OR NEW.password = OLD.password) THEN
            SET NEW.password = OLD.password;
            SET NEW.password = Password(NEW.Password);
      END IF;


Conveniently map between enum and int / String

If you have a class Car

public class Car {
    private Color externalColor;

And the property Color is a class

public class Color {
    private Integer id;
    private String name;

And you want to convert Color to an Enum

public class CarDTO {
    private ColorEnum externalColor;

Simply add a method in Color class to convert Color in ColorEnum

public class Color {
    private Integer id;
    private String name;

    public ColorEnum getEnum(){

and inside ColorEnum implements the method getById()

public enum ColorEnum {
    public static ColorEnum getById(int id) {
        for(ColorEnum e : values()) {
                return e;

Now you can use a classMap

private MapperFactory factory = new DefaultMapperFactory.Builder().build();
factory.classMap(Car.class, CarDTO.class)
CarDTO dto =, CarDTO.class);

Pass a PHP array to a JavaScript function

You can pass PHP arrays to JavaScript using json_encode PHP function.

    $phpArray = array(
        0 => "Mon", 
        1 => "Tue", 
        2 => "Wed", 
        3 => "Thu",
        4 => "Fri", 
        5 => "Sat",
        6 => "Sun",

<script type="text/javascript">

    var jArray = <?php echo json_encode($phpArray); ?>;

    for(var i=0; i<jArray.length; i++){


Float to String format specifier

You can pass a format string to the ToString method, like so:

ToString("N4"); // 4 decimal points Number

If you want to see more modifiers, take a look at MSDN - Standard Numeric Format Strings

HTTP 400 (bad request) for logical error, not malformed request syntax

In my case:

I am getting 400 bad request because I set content-type wrongly. I changed content type then able to get response successfully.

Before (Issue):

ClientResponse response = Client.create().resource(requestUrl).queryParam("noOfDates", String.valueOf(limit))
                .header(SecurityConstants.AUTHORIZATION, formatedToken).
header("Content-Type", "\"application/json\"").get(ClientResponse.class);

After (Fixed):

ClientResponse response = Client.create().resource(requestUrl).queryParam("noOfDates", String.valueOf(limit))
                .header(SecurityConstants.AUTHORIZATION, formatedToken).
header("Content-Type", "\"application/x-www-form-urlencoded\"").get(ClientResponse.class);

How do the major C# DI/IoC frameworks compare?

Just read this great .Net DI container comparison blog by Philip Mat.

He does some thorough performance comparison tests on;

He recommends Autofac as it is small, fast, and easy to use ... I agree. It appears that Unity and Ninject are the slowest in his tests.

Spring @ContextConfiguration how to put the right location for the xml

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = {"/Beans.xml"}) public class DemoTest{}

How to sort in mongoose?

Chaining with the query builder interface in Mongoose 4.

// Build up a query using chaining syntax. Since no callback is passed this will create an instance of Query.
var query = Person.
    find({ occupation: /host/ }).
    where('name.last').equals('Ghost'). // find each Person with a last name matching 'Ghost'
    where('likes').in(['vaporizing', 'talking']).
    sort('-occupation'). // sort by occupation in decreasing order
    select('name occupation'); // selecting the `name` and `occupation` fields

// Excute the query at a later time.
query.exec(function (err, person) {
    if (err) return handleError(err);
    console.log('%s %s is a %s.',,, person.occupation) // Space Ghost is a talk show host

See the docs for more about queries.

Fixed Table Cell Width

table { 
    table-layout:fixed; width:200px;
table tr {
    height: 20px;


Fast and Lean PDF Viewer for iPhone / iPad / iOS - tips and hints?

I have build such kind of application using approximatively the same approach except :

  • I cache the generated image on the disk and always generate two to three images in advance in a separate thread.
  • I don't overlay with a UIImage but instead draw the image in the layer when zooming is 1. Those tiles will be released automatically when memory warnings are issued.

Whenever the user start zooming, I acquire the CGPDFPage and render it using the appropriate CTM. The code in - (void)drawLayer: (CALayer*)layer inContext: (CGContextRef) context is like :

CGAffineTransform currentCTM = CGContextGetCTM(context);    
if (currentCTM.a == 1.0 && baseImage) {
    //Calculate ideal scale
    CGFloat scaleForWidth = baseImage.size.width/self.bounds.size.width;
    CGFloat scaleForHeight = baseImage.size.height/self.bounds.size.height; 
    CGFloat imageScaleFactor = MAX(scaleForWidth, scaleForHeight);

    CGSize imageSize = CGSizeMake(baseImage.size.width/imageScaleFactor, baseImage.size.height/imageScaleFactor);
    CGRect imageRect = CGRectMake((self.bounds.size.width-imageSize.width)/2, (self.bounds.size.height-imageSize.height)/2, imageSize.width, imageSize.height);
    CGContextDrawImage(context, imageRect, [baseImage CGImage]);
} else {
    @synchronized(issue) { 
        CGPDFPageRef pdfPage = CGPDFDocumentGetPage(issue.pdfDoc, pageIndex+1);
        pdfToPageTransform = CGPDFPageGetDrawingTransform(pdfPage, kCGPDFMediaBox, layer.bounds, 0, true);
        CGContextConcatCTM(context, pdfToPageTransform);    
        CGContextDrawPDFPage(context, pdfPage);

issue is the object containg the CGPDFDocumentRef. I synchronize the part where I access the pdfDoc property because I release it and recreate it when receiving memoryWarnings. It seems that the CGPDFDocumentRef object do some internal caching that I did not find how to get rid of.

jQuery: Setting select list 'selected' based on text, failing strangely

I usually use:

$("#my-Select option[text='" + myText +"']").attr("selected","selected") ;

#pragma pack effect

Note that there are other ways of achieving data consistency that #pragma pack offers (for instance some people use #pragma pack(1) for structures that should be sent across the network). For instance, see the following code and its subsequent output:

#include <stdio.h>

struct a {
    char one;
    char two[2];
    char eight[8];
    char four[4];

struct b { 
    char one;
    short two;
    long int eight;
    int four;

int main(int argc, char** argv) {
    struct a twoa[2] = {}; 
    struct b twob[2] = {}; 
    printf("sizeof(struct a): %i, sizeof(struct b): %i\n", sizeof(struct a), sizeof(struct b));
    printf("sizeof(twoa): %i, sizeof(twob): %i\n", sizeof(twoa), sizeof(twob));

The output is as follows: sizeof(struct a): 15, sizeof(struct b): 24 sizeof(twoa): 30, sizeof(twob): 48

Notice how the size of struct a is exactly what the byte count is, but struct b has padding added (see this for details on the padding). By doing this as opposed to the #pragma pack you can have control of converting the "wire format" into the appropriate types. For instance, "char two[2]" into a "short int" et cetera.

Types in MySQL: BigInt(20) vs Int(20)

I wanted to add one more point is, if you are storing a really large number like 902054990011312 then one can easily see the difference of INT(20) and BIGINT(20). It is advisable to store in BIGINT.

Click outside menu to close in jquery

Use the ':visible' selector. Where .menuitem is the to-hide element(s) ...


Or if you already have the .menuitem element(s) in a var ...

var menitems = $('.menuitem');

PowerShell Script to Find and Replace for all Files with a Specific Extension

This powershell example looks for all instances of the string "\foo\" in a folder and its subfolders, replaces "\foo\" with "\bar\" AND DOES NOT REWRITE files that don't contain the string "\foo\" This way you don't destroy the file last update datetime stamps where the string was not found:

Get-ChildItem  -Path C:\YOUR_ROOT_PATH\*.* -recurse 
 | ForEach {If (Get-Content $_.FullName | Select-String -Pattern '\\foo\\') 
           {(Get-Content $_ | ForEach {$_ -replace '\\foo\\', '\bar\'}) | Set-Content $_ }

jquery $(window).width() and $(window).height() return different values when viewport has not been resized

Try to use a

  • $(window).load event


  • $(document).ready

    because the initial values may be inconstant because of changes that occur during the parsing or during the DOM load.

How to properly override clone method?

Use serialization to make deep copies. This is not the quickest solution but it does not depend on the type.

How to Find the Default Charset/Encoding in Java?

The behaviour is not really that strange. Looking into the implementation of the classes, it is caused by:

  • Charset.defaultCharset() is not caching the determined character set in Java 5.
  • Setting the system property "file.encoding" and invoking Charset.defaultCharset() again causes a second evaluation of the system property, no character set with the name "Latin-1" is found, so Charset.defaultCharset() defaults to "UTF-8".
  • The OutputStreamWriter is however caching the default character set and is probably used already during VM initialization, so that its default character set diverts from Charset.defaultCharset() if the system property "file.encoding" has been changed at runtime.

As already pointed out, it is not documented how the VM must behave in such a situation. The Charset.defaultCharset() API documentation is not very precise on how the default character set is determined, only mentioning that it is usually done on VM startup, based on factors like the OS default character set or default locale.

Retrieving JSON Object Literal from HttpServletRequest

are you looking for this ?

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    StringBuilder sb = new StringBuilder();
    BufferedReader reader = request.getReader();
    try {
        String line;
        while ((line = reader.readLine()) != null) {
    } finally {

Function pointer as a member of a C struct

Maybe I am missing something here, but did you allocate any memory for that PString before you accessed it?

PString * initializeString() {
    PString *str;
    str = (PString *) malloc(sizeof(PString));
    str->length = &length;
    return str;

How do I set Tomcat Manager Application User Name and Password for NetBeans?

Go to apache-tomcat\conf folder add these lines in

tomcat-users.xml file

<role rolename="manager-gui"/>
<user username="admin" password="admin" roles="manager-gui"/>

and restart server

System.Security.SecurityException when writing to Event Log

Had a similar issue with all of our 2008 servers. The security log stopped working altogether because of a GPO that took the group Authenticated Users and read permission away from the key HKLM\System\CurrentControlSet\Services\EventLog\security

Putting this back per Microsoft's recommendation corrected the issue. I suspect giving all authenticated users read at a higher level will also correct your problem.

jQuery to retrieve and set selected option value of html select element

The way you have it is correct at the moment. Either the id of the select is not what you say or you have some issues in the dom.

Check the Id of the element and also check your markup validates at here at W3c.

Without a valid dom jQuery cannot work correctly with the selectors.

If the id's are correct and your dom validates then the following applies:

To Read Select Option Value


To Set Select Option Value


To Read Selected Text


Are SSL certificates bound to the servers ip address?

The SSL certificates are going to be bound to hostname rather than IP if they are setup in the standard way. Hence why it works at one site rather than the other.

Even if the servers share the same hostname they may well have two different certificates and hence WebSphere will have a certificate trust issue as it won't be able to recognise the certificate on the second server as it is different to the first.

What is the difference between Cloud Computing and Grid Computing?

Cloud Computing is a large group of interconnected computers.The data are hidden form the user. Grid computing is more than one computers interconnected to resolve the problem.grid computing is worked in cloud computing.

Use of "this" keyword in formal parameters for static methods in C#

This is an extension method. See here for an explanation.

Extension methods allow developers to add new methods to the public contract of an existing CLR type, without having to sub-class it or recompile the original type. Extension Methods help blend the flexibility of "duck typing" support popular within dynamic languages today with the performance and compile-time validation of strongly-typed languages.

Extension Methods enable a variety of useful scenarios, and help make possible the really powerful LINQ query framework... .

it means that you can call

MyClass myClass = new MyClass();
int i = myClass.Foo();

rather than

MyClass myClass = new MyClass();
int i = Foo(myClass);

This allows the construction of fluent interfaces as stated below.

PHPDoc type hinting for array of objects?

In NetBeans 7.0 (may be lower too) you could declare the the return type "array with Text objects " just as @return Text and the code hinting will work:

Edit: updated the example with @Bob Fanger suggestion

 * get all Tests
 * @return Test|Array $tests
public function getAllTexts(){
    return array(new Test(), new Test());

and just use it:

$tests =  $controller->getAllTests();
//$tests->         //codehinting works!
//$tests[0]->      //codehinting works!

foreach($tests as $text){
    //$test->      //codehinting works!

It is not perfect but it is better then just to leave it just "mixed", which brings no value.

CONS is you are allowed to tread the array as Text Object which will throw errors.

iPhone Navigation Bar Title text color

Short and sweet.

[[[self navigationController] navigationBar] setTitleTextAttributes:@{NSForegroundColorAttributeName: [UIColor redColor]}];

Watching variables in SSIS during debug

Visual Studio 2013: Yes to both adding to the watch windows during debugging and dragging variables or typing them in without "user::". But before any of that would work I also needed to go to Tools > Options, then Debugging > General and had to scroll right down to the bottom of the right hand pane to be able to tick "Use Managed Compatibility Mode". Then I had to stop and restart debugging. Finally the above advice worked. Many thanks to the above and to this article: Visual Studio 2015 Debugging: Can't expand local variables?

How to write the Fibonacci Sequence?

Fibonacci series in python,by creating null list:

                   inp=int(input())     #size of the series example it is 7
                   x=[]                 #blank list
                   x.insert(0,0)    #initially insert 0th position 0 element
                   for i in range(0,inp-1):
                    n=n1                  #swapping the value
                    x.append(n)          #append all the values to null list
                   for i in x:        #run this loop so ans is 0 1 1 2 3 5 8
                    print(i,end=" ")

HttpContext.Current.Session is null when routing requests

It seems that you have forgotten to add your state server address in the config file.

 <sessionstate mode="StateServer" timeout="20" server="" port="42424" />

Which is faster: Stack allocation or Heap allocation

Probably the biggest problem of heap allocation versus stack allocation, is that heap allocation in the general case is an unbounded operation, and thus you can't use it where timing is an issue.

For other applications where timing isn't an issue, it may not matter as much, but if you heap allocate a lot, this will affect the execution speed. Always try to use the stack for short lived and often allocated memory (for instance in loops), and as long as possible - do heap allocation during application startup.

Unit Testing C Code

You also might want to take a look at libtap, a C testing framework which outputs the Test Anything Protocol (TAP) and thus integrates well with a variety of tools coming out for this technology. It's mostly used in the dynamic language world, but it's easy to use and becoming very popular.

An example:

#include <tap.h>

int main () {

    ok(3 == 3);
    is("fnord", "eek", "two different strings not that way?");
    ok(3 <= 8732, "%d <= %d", 3, 8732);
    like("fnord", "f(yes|no)r*[a-f]$");
    cmp_ok(3, ">=", 10);


Adding extra zeros in front of a number using jQuery?

If you split on the space, you can add leading zeros using a simple function like:

function addZeros(n) {
  return (n < 10)? '00' + n : (n < 100)? '0' + n : '' + n;

So you can test the length of the string and if it's less than 6, split on the space, add zeros to the number, then join it back together.

Or as a regular expression:

function addZeros(s) {
  return s.replace(/ (\d$)/,' 00$1').replace(/ (\d\d)$/,' 0$1');

I'm sure someone can do it with one replace, not two.

Edit - examples

alert(addZeros('MR 3'));    // MR 003
alert(addZeros('MR 23'));   // MR 023
alert(addZeros('MR 123'));  // MR 123
alert(addZeros('foo bar 23'));  // foo bar 023

It will put one or two zeros infront of a number at the end of a string with a space in front of it. It doesn't care what bit before the space is.

Hibernate: Automatically creating/updating the db tables based on entity classes

You might try changing this line in your persistence.xml from

<property name="" value="create"/>


<property name="" value="update"/>

This is supposed to maintain the schema to follow any changes you make to the Model each time you run the app.

Got this from JavaRanch

How do I change the background color of a plot made with ggplot2

To change the panel's background color, use the following code:

myplot + theme(panel.background = element_rect(fill = 'green', colour = 'red'))

To change the color of the plot (but not the color of the panel), you can do:

myplot + theme(plot.background = element_rect(fill = 'green', colour = 'red'))

See here for more theme details Quick reference sheet for legends, axes and themes.

How to improve a case statement that uses two columns

You could do it this way:

-- Notice how STATE got moved inside the condition:
CASE WHEN STATE = 2 AND RetailerProcessType IN (1, 2) THEN '"AUTHORISED"'
     WHEN STATE = 1 AND RetailerProcessType = 2 THEN '"PENDING"'

The reason you can do an AND here is that you are not checking the CASE of STATE, but instead you are CASING Conditions.

The key part here is that the STATE condition is a part of the WHEN.

How to store a list in a column of a database table

I'd just store it as CSV, if it's simple values then it should be all you need (XML is very verbose and serializing to/from it would probably be overkill but that would be an option as well).

Here's a good answer for how to pull out CSVs with LINQ.

What is NODE_ENV and how to use it in Express?

NODE_ENV is an environment variable made popular by the express web server framework. When a node application is run, it can check the value of the environment variable and do different things based on the value. NODE_ENV specifically is used (by convention) to state whether a particular environment is a production or a development environment. A common use-case is running additional debugging or logging code if running in a development environment.

Accessing NODE_ENV

You can use the following code to access the environment variable yourself so that you can perform your own checks and logic:

var environment = process.env.NODE_ENV

Assume production if you don't recognise the value:

var isDevelopment = environment === 'development'

if (isDevelopment) {

You can alternatively using express' app.get('env') function, but note that this is NOT RECOMMENDED as it defaults to "development", which may result in development code being accidentally run in a production environment - it's much safer if your app throws an error if this important value is not set (or if preferred, defaults to production logic as above).

Be aware that if you haven't explicitly set NODE_ENV for your environment, it will be undefined if you access it from process.env, there is no default.

Setting NODE_ENV

How to actually set the environment variable varies from operating system to operating system, and also depends on your user setup.

If you want to set the environment variable as a one-off, you can do so from the command line:

  • linux & mac: export NODE_ENV=production
  • windows: $env:NODE_ENV = 'production'

In the long term, you should persist this so that it isn't unset if you reboot - rather than list all the possible methods to do this, I'll let you search how to do that yourself!

Convention has dictated that there are two 'main' values you should use for NODE_ENV, either production or development, all lowercase. There's nothing to stop you from using other values, (test, for example, if you wish to use some different logic when running automated tests), but be aware that if you are using third-party modules, they may explicitly compare with 'production' or 'development' to determine what to do, so there may be side effects that aren't immediately obvious.

Finally, note that it's a really bad idea to try to set NODE_ENV from within a node application itself - if you do, it will only be applied to the process from which it was set, so things probably won't work like you'd expect them to. Don't do it - you'll regret it.

angularjs: ng-src equivalent for background-image:url(...)

The above answer doesn't support observable interpolation (and cost me a lot of time trying to debug). The jsFiddle link in @BrandonTilley comment was the answer that worked for me, which I'll re-post here for preservation:

app.directive('backImg', function(){
    return function(scope, element, attrs){
        attrs.$observe('backImg', function(value) {
                'background-image': 'url(' + value +')',
                'background-size' : 'cover'

Example using controller and template

Controller :

$scope.someID = ...;
The advantage of using directive will also work inside an ng-repeat :
someID can be inside an array of ID's 

$scope.arrayOfIDs = [0,1,2,3];

Template :

Use in template like so :

<div back-img="img/service-sliders/{{someID}}/1.jpg"></div>

or like so :

<div ng-repeat="someID in arrayOfIDs" back-img="img/service-sliders/{{someID}}/1.jpg"></div>

Better way to find index of item in ArrayList?

The best way to find the position of item in the list is by using Collections interface,


List<Integer> sampleList = Arrays.asList(10,45,56,35,6,7);
Collections.binarySearch(sampleList, 56);

Output : 2

Getting a link to go to a specific section on another page

You can simply use

 <a href="directry/filename.html#section5" >click me</a>

to link to a section/id of another page by

ls command: how can I get a recursive full-path listing, one line per file?

Best command is: tree -fi

-f print the full path prefix for each file
-i don't print indentations


$ tree -fi

In order to use the files but not the links, you have to remove > from your output:

tree -fi |grep -v \>

If you want to know the nature of each file, (to read only ASCII files for example) with two whiles:

tree -fi | \
grep -v \> | \
while read first ; do 
    file ${first}
done | \
while read second; do 
    echo ${second} | grep ASCII

mysql query: SELECT DISTINCT column1, GROUP BY column2

you can use COUNT(DISTINCT ip), this will only count distinct values

How do I remove a specific element from a JSONArray?

We can use iterator to filter out the array entries instead of creating a new  Array. 

'public static void removeNullsFrom(JSONArray array) throws JSONException {
                if (array != null) {
                    Iterator<Object> iterator = array.iterator();
                    while (iterator.hasNext()) {
                        Object o =;
                        if (o == null || o == JSONObject.NULL) {

Switch/toggle div (jQuery)

I used this way to do that for multiple blocks without conjuring new JavaScript code:

<a href="#" data-toggle="thatblock">Show/Hide Content</a>

<div id="thatblock" style="display: none">
  Here is some description that will appear when we click on the button

Then a JavaScript portion for all such cases:

$(function() {
  $('*[data-toggle]').click(function() {
    return false;

Convert Java string to Time, NOT Date

try {

    SimpleDateFormat format = new SimpleDateFormat("hh:mm a"); //if 24 hour format
    // or
    SimpleDateFormat format = new SimpleDateFormat("HH:mm"); // 12 hour format

    java.util.Date d1 =(java.util.Date)format.parse(your_Time);

    java.sql.Time ppstime = new java.sql.Time(d1.getTime());

} catch(Exception e) {

    Log.e("Exception is ", e.toString());

What does "<html xmlns="">" do?

The namespace name 
is intended for use in various specifications such as:


    XHTML™ 1.0: The Extensible HyperText Markup Language
    XHTML Modularization
    XHTML 1.1
    XHTML Basic
    XHTML Print

Check here for more detail

.NET - Get protocol, host, and port

Very similar to Holger's answer. If you need to grab the URL can do something like:

Uri uri = Context.Request.Url;         
var scheme = uri.Scheme // returns http, https
var scheme2 = uri.Scheme + Uri.SchemeDelimiter; // returns http://, https://
var host = uri.Host; // return
var port = uri.Port; // returns port number

The Uri class provides a whole range of methods, many which I have not listed.

In my instance, I needed to grab LocalHost along with the Port Number, so this is what I did:

var Uri uri = Context.Request.Url;
var host = uri.Scheme + Uri.SchemeDelimiter + uri.Host + ":" + uri.Port; 

Which successfully grabbed: http://localhost:12345

Task vs Thread differences



Thread represents an actual OS-level thread, with its own stack and kernel resources. (technically, a CLR implementation could use fibers instead, but no existing CLR does this) Thread allows the highest degree of control; you can Abort() or Suspend() or Resume() a thread (though this is a very bad idea), you can observe its state, and you can set thread-level properties like the stack size, apartment state, or culture.

The problem with Thread is that OS threads are costly. Each thread you have consumes a non-trivial amount of memory for its stack, and adds additional CPU overhead as the processor context-switch between threads. Instead, it is better to have a small pool of threads execute your code as work becomes available.

There are times when there is no alternative Thread. If you need to specify the name (for debugging purposes) or the apartment state (to show a UI), you must create your own Thread (note that having multiple UI threads is generally a bad idea). Also, if you want to maintain an object that is owned by a single thread and can only be used by that thread, it is much easier to explicitly create a Thread instance for it so you can easily check whether code trying to use it is running on the correct thread.


ThreadPool is a wrapper around a pool of threads maintained by the CLR. ThreadPool gives you no control at all; you can submit work to execute at some point, and you can control the size of the pool, but you can't set anything else. You can't even tell when the pool will start running the work you submit to it.

Using ThreadPool avoids the overhead of creating too many threads. However, if you submit too many long-running tasks to the threadpool, it can get full, and later work that you submit can end up waiting for the earlier long-running items to finish. In addition, the ThreadPool offers no way to find out when a work item has been completed (unlike Thread.Join()), nor a way to get the result. Therefore, ThreadPool is best used for short operations where the caller does not need the result.


Finally, the Task class from the Task Parallel Library offers the best of both worlds. Like the ThreadPool, a task does not create its own OS thread. Instead, tasks are executed by a TaskScheduler; the default scheduler simply runs on the ThreadPool.

Unlike the ThreadPool, Task also allows you to find out when it finishes, and (via the generic Task) to return a result. You can call ContinueWith() on an existing Task to make it run more code once the task finishes (if it's already finished, it will run the callback immediately). If the task is generic, ContinueWith() will pass you the task's result, allowing you to run more code that uses it.

You can also synchronously wait for a task to finish by calling Wait() (or, for a generic task, by getting the Result property). Like Thread.Join(), this will block the calling thread until the task finishes. Synchronously waiting for a task is usually bad idea; it prevents the calling thread from doing any other work, and can also lead to deadlocks if the task ends up waiting (even asynchronously) for the current thread.

Since tasks still run on the ThreadPool, they should not be used for long-running operations, since they can still fill up the thread pool and block new work. Instead, Task provides a LongRunning option, which will tell the TaskScheduler to spin up a new thread rather than running on the ThreadPool.

All newer high-level concurrency APIs, including the Parallel.For*() methods, PLINQ, C# 5 await, and modern async methods in the BCL, are all built on Task.


The bottom line is that Task is almost always the best option; it provides a much more powerful API and avoids wasting OS threads.

The only reasons to explicitly create your own Threads in modern code are setting per-thread options, or maintaining a persistent thread that needs to maintain its own identity.

How to set corner radius of imageView?

try this

self.mainImageView.layer.cornerRadius = CGRectGetWidth(self.mainImageView.frame)/4.0
self.mainImageView.clipsToBounds = true

change background image in body

Just set an onload function on the body:

<body onload="init()">

Then do something like this in javascript:

function init() {
  var someimage = 'changableBackgroudImage'; = 'url(img/'+someimage+'.png) no-repeat center center'

You can change the 'someimage' variable to whatever you want depending on some conditions, such as the time of day or something, and that image will be set as the background image.

Disable browser's back button

I came up with a little hack that disables the back button using JavaScript. I checked it on chrome 10, firefox 3.6 and IE9:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="" >
<title>Untitled Page</title>
<script type = "text/javascript" >
function changeHashOnLoad() {
     window.location.href += "#";
     setTimeout("changeHashAgain()", "50"); 

function changeHashAgain() {
  window.location.href += "1";

var storedHash = window.location.hash;
window.setInterval(function () {
    if (window.location.hash != storedHash) {
         window.location.hash = storedHash;
}, 50);

<body onload="changeHashOnLoad(); ">
Try to hit the back button!

What is it doing?

From Comments:

This script leverages the fact that browsers consider whatever comes after the "#" sign in the URL as part of the browsing history. What it does is this: When the page loads, "#1" is added to the URL. After 50ms the "1" is removed. When the user clicks "back", the browser changes the URL back to what it was before the "1" was removed, BUT - it's the same web page, so the browser doesn't need to reload the page. – Yossi Shasho

1030 Got error 28 from storage engine

Check your /backup to see if you can delete an older not needed backup.

Jquery $(this) Child Selector

The best way with the HTML you have would probably be to use the next function, like so:

var div = $(this).next('.class2');

Since the click handler is happening to the <a>, you could also traverse up to the parent DIV, then search down for the second DIV. You would do this with a combination of parent and children. This approach would be best if the HTML you put up is not exactly like that and the second DIV could be in another location relative to the link:

var div = $(this).parent().children('.class2');

If you wanted the "search" to not be limited to immediate children, you would use find instead of children in the example above.

Also, it is always best to prepend your class selectors with the tag name if at all possible. ie, if only <div> tags are going to have those classes, make the selector be div.class1, div.class2.

javac is not recognized as an internal or external command, operable program or batch file

Check your environment variables.

In my case I had JAVA_HOME set in the System variables as well as in my User Account variables and the latter was set to a wrong version of Java. I also had the same problem with the Path variable.

After deleting JAVA_HOME from my User Account variables and removing the wrong path from the Path variable it worked correctly.

How to permanently remove few commits from remote branch

You git reset --hard your local branch to remove changes from working tree and index, and you git push --force your revised local branch to the remote. (other solution here, involving deleting the remote branch, and re-pushing it)

This SO answer illustrates the danger of such a command, especially if people depends on the remote history for their own local repos.
You need to be prepared to point out people to the RECOVERING FROM UPSTREAM REBASE section of the git rebase man page

With Git 2.23 (August 2019, nine years later), you would use the new command git switch.
That is: git switch -C mybranch origin/mybranch~n
(replace n by the number of commits to remove)

That will restore the index and working tree, like a git reset --hard would.
The documentation adds:

-C <new-branch>
--force-create <new-branch>

Similar to --create except that if <new-branch> already exists, it will be reset to <start-point>.
This is a convenient shortcut for:

$ git branch -f <new-branch>
$ git switch <new-branch>

Hibernate SessionFactory vs. JPA EntityManagerFactory

Prefer EntityManagerFactory and EntityManager. They are defined by the JPA standard.

SessionFactory and Session are hibernate-specific. The EntityManager invokes the hibernate session under the hood. And if you need some specific features that are not available in the EntityManager, you can obtain the session by calling:

Session session = entityManager.unwrap(Session.class);

Kill process by name?

import os, signal

def check_kill_process(pstring):
    for line in os.popen("ps ax | grep " + pstring + " | grep -v grep"):
        fields = line.split()
        pid = fields[0]
        os.kill(int(pid), signal.SIGKILL)

How can I join on a stored procedure?

It has already been answered, the best way work-around is to convert the Stored Procedure into an SQL Function or a View.

The short answer, just as mentioned above, is that you cannot directly JOIN a Stored Procedure in SQL, not unless you create another stored procedure or function using the stored procedure's output into a temporary table and JOINing the temporary table, as explained above.

I will answer this by converting your Stored Procedure into an SQL function and show you how to use it inside a query of your choice.

  SELECT tenant.ID AS TenantID, 
       SUM(ISNULL(trans.Amount,0)) AS TenantBalance 
  FROM tblTenant tenant
    LEFT JOIN tblTransaction trans ON tenant.ID = trans.TenantID
  GROUP BY tenant.ID

Now to use that function, in your SQL...

SELECT t.TenantName, 
FROM tblTenant t
    LEFT JOIN tblRentalUnit u ON t.UnitID = u.ID
    LEFT JOIN tblProperty p ON u.PropertyID = p.ID
    LEFT JOIN dbo.fnMyFunc() AS a
         ON a.TenantID = t.TenantID
ORDER BY p.PropertyName, t.CarPlateNumber

If you wish to pass parameters into your function from within the above SQL, then I recommend you use CROSS APPLY or CROSS OUTER APPLY.

Read up on that here.


Bootstrap 3.0 Sliding Menu from left

I believe that although javascript is an option here, you have a smoother animation through forcing hardware accelerate with CSS3. You can achieve this by setting the following CSS3 properties on the moving div:

div.hardware-accelarate {
     -webkit-transform: translate3d(0,0,0);
        -moz-transform: translate3d(0,0,0);
         -ms-transform: translate3d(0,0,0);
          -o-transform: translate3d(0,0,0);
             transform: translate3d(0,0,0);

I've made a plunkr setup for ya'll to test and tweak...

Android: ScrollView vs NestedScrollView

NestedScrollView as the name suggests is used when there is a need for a scrolling view inside another scrolling view. Normally this would be difficult to accomplish since the system would be unable to decide which view to scroll.

This is where NestedScrollView comes in.

Environment variables in Eclipse

The .bashrc file is used for setting variables used by interactive login shells. If you want those environment variables available in Eclipse you need to put them in /etc/environment.

How to downgrade or install an older version of Cocoapods

Several notes:

Make sure you first get a list of all installed versions. I actually had the version I wanted to downgrade to already installed, but ended up uninstalling that as well. To see the list of all your versions do:

sudo gem list cocoapods

Then when you want to delete a version, specify that version.

sudo gem uninstall cocoapods -v 1.6.2

You could remove the version specifier -v 1.6.2 and that would delete all versions:

You may try all this and still see that the Cocoapods you expected is still installed. If that's the case then it might be because Cocoaposa is stored in a different directory.

sudo gem uninstall -n /usr/local/bin cocoapods -v 1.6.2

Then you will have to also install it in a different directory, otherwise you may get an error saying You don't have write permissions for the /usr/bin directory

sudo gem install -n /usr/local/bin cocoapods -v 1.6.1

To check which version is your default do:

pod --version

For more on the directory problem see here

Is there a CSS selector for text nodes?

Text nodes cannot have margins or any other style applied to them, so anything you need style applied to must be in an element. If you want some of the text inside of your element to be styled differently, wrap it in a span or div, for example.

Directly assigning values to C Pointers

In the first example, ptr has not been initialized, so it points to an unspecified memory location. When you assign something to this unspecified location, your program blows up.

In the second example, the address is set when you say ptr = &q, so you're OK.

Error #2032: Stream Error

From a quick google search it seems that the problem is a file or url couldn't be found be the HTTPservice.

Here are the links where I found this information:

ImportError: No module named 'encodings'

I was facing this issue "ModuleNotFoundError: No module named 'encodings" after updating to macOS Catalina.

I was having multiple versions of Python installed in my system.

Removing all the python versions(2.7 and 3.7.4) from macOS system and reinstalling the latest python 3.8 worked for me.

To remove a python from macOS, I've followed the instructions from here How to uninstall Python 2.7 on a Mac OS X 10.6.4?

The above link is for python 2.7 and but you can use the same for 3.7 also.

Class 'ViewController' has no initializers in swift

The Swift Programming Language states:

Classes and structures must set all of their stored properties to an appropriate initial value by the time an instance of that class or structure is created. Stored properties cannot be left in an indeterminate state.

You can set an initial value for a stored property within an initializer, or by assigning a default property value as part of the property’s definition.

Therefore, you can write:

class myClass {

    var delegate: AppDelegate //non-optional variable

    init() {
        delegate = UIApplication.sharedApplication().delegate as AppDelegate



class myClass {

    var delegate = UIApplication.sharedApplication().delegate as AppDelegate //non-optional variable

    init() {



class myClass {

    var delegate : AppDelegate! //implicitly unwrapped optional variable set to nil when class is initialized

    init() {

    func myMethod() {
        delegate = UIApplication.sharedApplication().delegate as AppDelegate


But you can't write the following:

class myClass {

    var delegate : AppDelegate //non-optional variable

    init() {

    func myMethod() {
        //too late to assign delegate as an non-optional variable
        delegate = UIApplication.sharedApplication().delegate as AppDelegate


How can I add 1 day to current date?

currentDay = '2019-12-06';
currentDay = new Date(currentDay).add(Date.DAY, +1).format('Y-m-d');

Get resultset from oracle stored procedure

Hi I know this was asked a while ago but I've just figured this out and it might help someone else. Not sure if this is exactly what you're looking for but this is how I call a stored proc and view the output using SQL Developer.
In SQL Developer when viewing the proc, right click and choose 'Run' or select Ctrl+F11 to bring up the Run PL/SQL window. This creates a template with the input and output params which you need to modify. My proc returns a sys_refcursor. The tricky part for me was declaring a row type that is exactly equivalent to the select stmt / sys_refcursor being returned by the proc:

  v_Return sys_refcursor;
  type t_row is record (CAE_SEC_ID NUMBER,FM_SEC_CODE VARCHAR2(7),rownum number, v_total_count number);
  v_rec t_row;

  P_PAGE_INDEX := 0;
  P_PAGE_SIZE := 25;

    P_FOF_SEC_REFCUR => v_Return
  -- Modify the code to output the variable
    fetch v_Return into v_rec;
    exit when v_Return%notfound;
    DBMS_OUTPUT.PUT_LINE('sec_id = ' || v_rec.CAE_SEC_ID || 'sec code = ' ||v_rec.FM_SEC_CODE);
  end loop;


Download data url file


  • Try a <a href="data:...." target="_blank"> (Untested)

  • Use downloadify instead of data URLs (would work for IE as well)

IllegalStateException: Can not perform this action after onSaveInstanceState with ViewPager

I found a dirty solution for this kind of problem. If you still want to keep your ActivityGroups for whatever reason (I had time limitation reasons), you just implement

public void onBackPressed() {}

in your Activity and do some back code in there. even if there is no such Method on older Devices, this Method gets called by newer ones.

What does "Use of unassigned local variable" mean?

Use "default"!!!

    string myString = default;
    double myDouble = defaul;

       myDouble = 1.5;

    return myDouble;

How to connect to SQL Server from command prompt with Windows authentication

Try This :

--Default Instance


--Named Instance




More details can be found here

Comparing floating point number to zero

If you are only interested in +0.0 and -0.0, you can use fpclassify from <cmath>. For instance:

if( FP_ZERO == fpclassify(x) ) do_something;

Problem with SMTP authentication in PHP using PHPMailer, with Pear Mail works

strange issue that i solved by comment this line


whit the last phpmailer version (5.2)

Is gcc's __attribute__((packed)) / #pragma pack unsafe?

Using this attribute is definitely unsafe.

One particular thing it breaks is the ability of a union which contains two or more structs to write one member and read another if the structs have a common initial sequence of members. Section of the C11 standard states:

6 One special guarantee is made in order to simplify the use of unions: if a union contains several structures that share a common initial sequence (see below), and if the union object currently contains one of these structures, it is permitted to inspect the common initial part of any of them anywhere that a declaration of the completed type of the union is visible. Tw o structures share a common initial sequence if corresponding members have compatible types (and, for bit-fields, the same widths) for a sequence of one or more initial members.


9 EXAMPLE 3 The following is a valid fragment:

union {
    struct {
        int    alltypes;
    struct {
        int    type;
        int    intnode;
    } ni;
    struct {
        int    type;
        double doublenode;
    } nf;
}u; = 1; = 3.14;
if (u.n.alltypes == 1)
if (sin( == 0.0)

When __attribute__((packed)) is introduced it breaks this. The following example was run on Ubuntu 16.04 x64 using gcc 5.4.0 with optimizations disabled:

#include <stdio.h>
#include <stdlib.h>

struct s1
    short a;
    int b;
} __attribute__((packed));

struct s2
    short a;
    int b;

union su {
    struct s1 x;
    struct s2 y;

int main()
    union su s;
    s.x.a = 0x1234;
    s.x.b = 0x56789abc;

    printf("sizeof s1 = %zu, sizeof s2 = %zu\n", sizeof(struct s1), sizeof(struct s2));
    printf("s.y.a=%hx, s.y.b=%x\n", s.y.a, s.y.b);
    return 0;


sizeof s1 = 6, sizeof s2 = 8
s.y.a=1234, s.y.b=5678

Even though struct s1 and struct s2 have a "common initial sequence", the packing applied to the former means that the corresponding members don't live at the same byte offset. The result is the value written to member x.b is not the same as the value read from member y.b, even though the standard says they should be the same.

How to save a plot as image on the disk?

If you open a device using png(), bmp(), pdf() etc. as suggested by Andrie (the best answer), the windows with plots will not pop up open, just *.png, *bmp or *.pdf files will be created. This is convenient in massive calculations, since R can handle only limited number of graphic windows.

However, if you want to see the plots and also have them saved, call savePlot(filename, type) after the plots are drawn and the window containing them is active.

Sum up a column from a specific row down

You all seem to love complication. Just click on column(to select entire column), press and hold CTRL and click on cells that you want to exclude(C1 to C5 in you case). Now you have selected entire column C (right to the end of sheet) without starting cells. All you have to do now is to rightclick and "Define Name" for your selection(ex. asdf ). In formula you use SUM(asdf). And now you're done. Good luck

Allways find the easyest way ;)

Split page vertically using CSS

There can also be a solution by having both float to left.

Try this out:

Working Demo

P.S. This is just an improvement of Ankit's Answer

What does set -e mean in a bash script?

This is an old question, but none of the answers here discuss the use of set -e aka set -o errexit in Debian package handling scripts. The use of this option is mandatory in these scripts, per Debian policy; the intent is apparently to avoid any possibility of an unhandled error condition.

What this means in practice is that you have to understand under what conditions the commands you run could return an error, and handle each of those errors explicitly.

Common gotchas are e.g. diff (returns an error when there is a difference) and grep (returns an error when there is no match). You can avoid the errors with explicit handling:

diff this that ||
  echo "$0: there was a difference" >&2
grep cat food ||
  echo "$0: no cat in the food" >&2

(Notice also how we take care to include the current script's name in the message, and writing diagnostic messages to standard error instead of standard output.)

If no explicit handling is really necessary or useful, explicitly do nothing:

diff this that || true
grep cat food || :

(The use of the shell's : no-op command is slightly obscure, but fairly commonly seen.)

Just to reiterate,

something || other

is shorthand for

if something; then
    : nothing

i.e. we explicitly say other should be run if and only if something fails. The longhand if (and other shell flow control statements like while, until) is also a valid way to handle an error (indeed, if it weren't, shell scripts with set -e could never contain flow control statements!)

And also, just to be explicit, in the absence of a handler like this, set -e would cause the entire script to immediately fail with an error if diff found a difference, or if grep didn't find a match.

On the other hand, some commands don't produce an error exit status when you'd want them to. Commonly problematic commands are find (exit status does not reflect whether files were actually found) and sed (exit status won't reveal whether the script received any input or actually performed any commands successfully). A simple guard in some scenarios is to pipe to a command which does scream if there is no output:

find things | grep .
sed -e 's/o/me/' stuff | grep ^

It should be noted that the exit status of a pipeline is the exit status of the last command in that pipeline. So the above commands actually completely mask the status of find and sed, and only tell you whether grep finally succeeded.

(Bash, of course, has set -o pipefail; but Debian package scripts cannot use Bash features. The policy firmly dictates the use of POSIX sh for these scripts, though this was not always the case.)

In many situations, this is something to separately watch out for when coding defensively. Sometimes you have to e.g. go through a temporary file so you can see whether the command which produced that output finished successfully, even when idiom and convenience would otherwise direct you to use a shell pipeline.

Wpf DataGrid Add new row

Just simply use this Style of DataGridRow:

        <Style TargetType="DataGridRow">
            <Setter Property="IsEnabled" Value="{Binding RelativeSource={RelativeSource Self},Path=IsNewItem,Mode=OneWay}" />

How do you set up use HttpOnly cookies in PHP

//None HttpOnly cookie:
setcookie("abc", "test", NULL, NULL, NULL, NULL, FALSE); 

//HttpOnly cookie:
setcookie("abc", "test", NULL, NULL, NULL, NULL, TRUE); 



How do I create a shortcut via command-line in Windows?

The best way is to run this batch file. open notepad and type:-

@echo off
echo Set oWS = WScript.CreateObject("WScript.Shell") > CreateShortcut.vbs
echo sLinkFile = "GIVETHEPATHOFLINK.lnk" >> CreateShortcut.vbs
echo Set oLink = oWS.CreateShortcut(sLinkFile) >> CreateShortcut.vbs
echo oLink.Save >> CreateShortcut.vbs
cscript CreateShortcut.vbs
del CreateShortcut.vbs

Save as filename.bat(be careful while saving select all file types) worked well in win XP.

is inaccessible due to its protection level

The reason being you can not access protected member data through the instance of the class.

Reason why it is not allowed is explained in this blog

Python float to int conversion

Languages that use binary floating point representations (Python is one) cannot represent all fractional values exactly. If the result of your calculation is 250.99999999999 (and it might be), then taking the integer part will result in 250.

A canonical article on this topic is What Every Computer Scientist Should Know About Floating-Point Arithmetic.

What MySQL data type should be used for Latitude/Longitude with 8 decimal places?

I believe the best way to store Lat/Lng in MySQL is to have a POINT column (2D datatype) with a SPATIAL index.

CREATE TABLE `cities` (
  `zip` varchar(8) NOT NULL,
  `country` varchar (2) GENERATED ALWAYS AS (SUBSTRING(`zip`, 1, 2)) STORED,
  `city` varchar(30) NOT NULL,
  `centre` point NOT NULL,
  PRIMARY KEY (`zip`),
  KEY `country` (`country`),
  KEY `city` (`city`),
  SPATIAL KEY `centre` (`centre`)

INSERT INTO `cities` (`zip`, `city`, `centre`) VALUES
('CZ-10000', 'Prague', POINT(50.0755381, 14.4378005));

How to convert string to float?

Why one should not use function atof() to convert string to double?

On success, atof() function returns the converted floating point number as a double value. If no valid conversion could be performed, the function returns zero (0.0). If the converted value would be out of the range of representable values by a double, it causes undefined behavior.


Instead use function strtod(), it is more robust.

Try this code:

int main()
    char s[100] = "4.0800";
    printf("Float value : %4.8f\n",strtod(s,NULL));
    return 0;

You will get the following output:

Float value : 4.08000000

How to download the latest artifact from Artifactory repository?

You can use the REST-API's "Item last modified". From the docs, it retuns something like this:

GET /api/storage/libs-release-local/org/acme?lastModified
"uri": "http://localhost:8081/artifactory/api/storage/libs-release-local/org/acme/foo/1.0-SNAPSHOT/foo-1.0-SNAPSHOT.pom",
"lastModified": ISO8601


# Figure out the URL of the last item modified in a given folder/repo combination
url=$(curl \
    'http://<artifactory-base-url>/api/storage/<repo>/<folder>?lastModified'  | jq -r '.uri')
# Figure out the name of the downloaded file
downloaded_filename=$(echo "${url}" | sed -e 's|[^/]*/||g')
# Download the file
curl -L -O "${url}"

How to make a vertical SeekBar in Android?


<RelativeLayout xmlns:android=""  
android:layout_height="match_parent" > 



What is the difference between state and props in React?

State is your data, is mutable, you can do anything you need with it, props is read only data, usually when you pass props you have already work with your data and you need the child component to render it or if your props is a function u call it to perform a task

Hibernate: How to fix "identifier of an instance altered from X to Y"?

Are you changing the primary key value of a User object somewhere? You shouldn't do that. Check that your mapping for the primary key is correct.

What does your mapping XML file or mapping annotations look like?

Can I change the fill color of an svg path with CSS?

if you want to change color by hovering in the element, try this:


RecyclerView - Get view at particular position

You can use below


Twitter API returns error 215, Bad Authentication Data

Try this twitter API explorer, you can sign in as a developer and query whatever you want.

HTML.ActionLink vs Url.Action in ASP.NET Razor

    @Html.ActionLink("Create New", "Create")
@using (Html.BeginForm("Index", "Company", FormMethod.Get))
        Find by Name: @Html.TextBox("SearchString", ViewBag.CurrentFilter as string)
        <input type="submit" value="Search" />
        <input type="button" value="Clear" onclick="location.href='@Url.Action("Index","Company")'"/>

In the above example you can see that If I specifically need a button to do some action, I have to do it with @Url.Action whereas if I just want a link I will use @Html.ActionLink. The point is when you have to use some element(HTML) with action url is used.

How can I determine whether a 2D Point is within a Polygon?

I did some work on this back when I was a researcher under Michael Stonebraker - you know, the professor who came up with Ingres, PostgreSQL, etc.

We realized that the fastest way was to first do a bounding box because it's SUPER fast. If it's outside the bounding box, it's outside. Otherwise, you do the harder work...

If you want a great algorithm, look to the open source project PostgreSQL source code for the geo work...

I want to point out, we never got any insight into right vs left handedness (also expressible as an "inside" vs "outside" problem...


BKB's link provided a good number of reasonable algorithms. I was working on Earth Science problems and therefore needed a solution that works in latitude/longitude, and it has the peculiar problem of handedness - is the area inside the smaller area or the bigger area? The answer is that the "direction" of the verticies matters - it's either left-handed or right handed and in this way you can indicate either area as "inside" any given polygon. As such, my work used solution three enumerated on that page.

In addition, my work used separate functions for "on the line" tests.

...Since someone asked: we figured out that bounding box tests were best when the number of verticies went beyond some number - do a very quick test before doing the longer test if necessary... A bounding box is created by simply taking the largest x, smallest x, largest y and smallest y and putting them together to make four points of a box...

Another tip for those that follow: we did all our more sophisticated and "light-dimming" computing in a grid space all in positive points on a plane and then re-projected back into "real" longitude/latitude, thus avoiding possible errors of wrapping around when one crossed line 180 of longitude and when handling polar regions. Worked great!

hide div tag on mobile view only?

Set the display property to none as the default, then use a media query to apply the desired styles to the div when the browser reaches a certain width. Replace 768px in the media query with whatever the minimum px value is where your div should be visible.

#title_message {
    display: none;

@media screen and (min-width: 768px) {
    #title_message {
        clear: both;
        display: block;
        float: left;
        margin: 10px auto 5px 20px;
        width: 28%;

Angular 2: Can't bind to 'ngModel' since it isn't a known property of 'input'

Step to follow

1. Open your app.module.ts file.


2. Add import { FormsModule } from '@angular/forms';


3. Add FormsModule to imports asimports: [ BrowserModule, FormsModule ],


Final result will look like this

import { FormsModule } from '@angular/forms';
  imports: [   
     BrowserModule, FormsModule 

What is the correct JSON content type?

The right content type for JSON is application/json UNLESS you're using JSONP, also known as JSON with Padding, which is actually JavaScript and so the right content type would be application/javascript.

"Could not find the main class" error when running jar exported by Eclipse

Have you renamed your project/main class (e.g. through refactoring) ? If yes your Launch Configuration might be set up incorrectly (e.g. refering to the old main class or configuration). Even though the project name appears in the 'export runnable jar' dialog, a closer inspection might reveal an unmatched main class name.

Go to 'Properties->Run/Debug Settings' of your project and make sure your Launch Configuration (the same used to export runnable jar) is set to the right name of project AND your main class is set to

Why use 'virtual' for class properties in Entity Framework model definitions?

It’s quite common to define navigational properties in a model to be virtual. When a navigation property is defined as virtual, it can take advantage of certain Entity Framework functionality. The most common one is lazy loading.

Lazy loading is a nice feature of many ORMs because it allows you to dynamically access related data from a model. It will not unnecessarily fetch the related data until it is actually accessed, thus reducing the up-front querying of data from the database.

From book "ASP.NET MVC 5 with Bootstrap and Knockout.js"

Add A Year To Today's Date

    var d = new Date();
    var year = d.getFullYear();
    var month = d.getMonth();
    var day = d.getDate();

    var fulldate = new Date(year + 1, month, day);

    var toDate = fulldate.toISOString().slice(0, 10);


    output : 2020-01-02

How can I decrease the size of Ratingbar?

If you want to show the rating bar in small size, then just copy and paste this code in your project.

    android:stepSize="0.1" />

How to disable right-click context-menu in JavaScript

Capture the onContextMenu event, and return false in the event handler.

You can also capture the click event and check which mouse button fired the event with event.button, in some browsers anyway.

Best Practices for securing a REST API / web service

For Web Application Security, you should take a look at OWASP ( which provides cheatsheets for various security attacks. You can incorporate as many measures as possible to secure your Application. With respect to API security (authorization, authentication, identity management), there are multiple ways as already mentioned (Basic,Digest and OAuth). There are loop holes in OAuth1.0, so you can use OAuth1.0a (OAuth2.0 is not widely adopted due to concerns with the specification)

Removing the password from a VBA project

Another way to remove VBA project password is;

  • Open xls file with a hex editor. (ie. Hex Edit
  • Search for DPB
  • Replace DPB to DPx
  • Save file.
  • Open file in Excel.
  • Click "Yes" if you get any message box.
  • Set new password from VBA Project Properties.
  • Close and open again file, then type your new password to unprotect.

UPDATE: For Excel 2010 (Works for MS Office Pro Plus 2010 [14.0.6023.1000 64bit]),

  • Open the XLSX file with 7zip

If workbook is protected:

  • Browse the folder xl
  • If the workbook is protected, right click workbook.xml and select Edit
  • Find the portion <workbookProtection workbookPassword="XXXX" lockStructure="1"/> (XXXX is your encrypted password)
  • Remove XXXX part. (ie. <workbookProtection workbookPassword="" lockStructure="1"/>)
  • Save the file.
  • When 7zip asks you to update the archive, say Yes.
  • Close 7zip and re-open your XLSX.
  • Click Protect Workbook on Review tab.
  • Optional: Save your file.

If worksheets are protected:

  • Browse to xl/worksheets/ folder.
  • Right click the Sheet1.xml, sheet2.xml, etc and select Edit.
  • Find the portion <sheetProtection password="XXXX" sheet="1" objects="1" scenarios="1" />
  • Remove the encrypted password (ie. <sheetProtection password="" sheet="1" objects="1" scenarios="1" />)
  • Save the file.
  • When 7zip asks you to update the archive, say Yes.
  • Close 7zip and re-open your XLSX.
  • Click Unprotect Sheet on Review tab.
  • Optional: Save your file.

to_string not declared in scope

//Try this if you can't use -std=c++11:-
int number=55;
char tempStr[32] = {0};
sprintf(tempStr, "%d", number);

How do I handle a click anywhere in the page, even when a certain element stops the propagation?

I think this is what you need:


This will allow you to trigger the body click event from anywhere.

How to check if an array element exists?

You can also use array_keys for number of occurrences

$i=count(array_keys($array, 6));
 echo "Element exists in Array";

Send file via cURL from form POST in PHP

This should work:

$tmpfile = $_FILES['image']['tmp_name'];
$filename = basename($_FILES['image']['name']);

$data = array(
    'uploaded_file' => '@'.$tmpfile.';filename='.$filename,

$ch = curl_init();   
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
// set your other cURL options here (url, etc.)


In the receiving script, you would have:

/* which would output something like
     Array (
        [uploaded_file] => Array (
            [tmp_name] => /tmp/f87453hf
            [name] => myimage.jpg
            [error] => 0
            [size] => 12345
            [type] => image/jpeg

Then, if you want to properly handle the file upload, you would do something like this:

if (move_uploaded_file($_FILES['uploaded_file'], '/path/to/destination/')) {
   // do stuff

What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?

Your first port of call should be the documentation which explains it reasonably clearly:

Thrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array.

So for example:

int[] array = new int[5];
int boom = array[10]; // Throws the exception

As for how to avoid it... um, don't do that. Be careful with your array indexes.

One problem people sometimes run into is thinking that arrays are 1-indexed, e.g.

int[] array = new int[5];
// ... populate the array here ...
for (int index = 1; index <= array.length; index++)

That will miss out the first element (index 0) and throw an exception when index is 5. The valid indexes here are 0-4 inclusive. The correct, idiomatic for statement here would be:

for (int index = 0; index < array.length; index++)

(That's assuming you need the index, of course. If you can use the enhanced for loop instead, do so.)

how to run two commands in sudo?

The -s option didn't work for me, -i did.

Here is an example of how I could update the log size from my bash:

sudo -u [user] -i -- sh -c 'db2 connect to [database name];db2 update db cfg for [database name] using logsecond 20;db2 update db cfg for [database name] using logprimary 20;'

Sum all the elements java arraylist

Using Java 8 streams:

double sum =
    .mapToDouble(a -> a)


Why is the apt-get function not working in the terminal on Mac OS X v10.9 (Mavericks)?

Alternatively You can use the brew or curl command for installing things, wherever apt-get is mentioned with a URL...

For example,

curl -O

ScrollTo function in AngularJS

In order to animate to a specific element inside a scroll container (fixed DIV)

    @param Container(DIV) that needs to be scrolled, ID or Div of the anchor element that should be scrolled to
    Scrolls to a specific element in the div container
this.scrollTo = function(container, anchor) {
    var element = angular.element(anchor);
    angular.element(container).animate({scrollTop: element.offset().top}, "slow");

Why does writeObject throw and how do I fix it?

The fields of your object have in turn their fields, some of which do not implement Serializable. In your case the offending class is TransformGroup. How to solve it?

  • if the class is yours, make it Serializable
  • if the class is 3rd party, but you don't need it in the serialized form, mark the field as transient
  • if you need its data and it's third party, consider other means of serialization, like JSON, XML, BSON, MessagePack, etc. where you can get 3rd party objects serialized without modifying their definitions.

Find first and last day for previous calendar month in SQL Server Reporting Services (VB.Net)

I was having some difficulty translating actual VB.NET to the Expression subset that SSRS uses. You definitely inspired me though and this is what I came up with.


End Date

I know it's a bit recursive for the StartDate (first day of last month). Is there anything I'm missing here? These are strictly date fields (i.e. no time), but I think this should capture leap year, etc.

How did I do?

Send FormData with other field in AngularJS

Using $resource in AngularJS you can do:


$ngTask.factory("$taskService", [
    function ($resource) {
        var taskModelUrl = 'api/task/';
        return {
            rest: {
                taskUpload: $resource(taskModelUrl, {
                    id: '@id'
                }, {
                    save: {
                        method: "POST",
                        isArray: false,
                        headers: {"Content-Type": undefined},
                        transformRequest: angular.identity

And then use it in a module:


$ngModelTask.controller("taskController", [
    function (
    ) {
    $scope.saveTask = function (name, file) {
        var newTask,
            payload = new FormData();
        payload.append("name", name);
        payload.append("file", file);
        newTask = $;
        // check if exists

Integer.toString(int i) vs String.valueOf(int i)

Using the method, String.valueOf() you do not have to worry about the data(whether it is int,long,char,char[],boolean,Object), you can just call :

  • static String valueOf()

using the only syntax String.valueOf() can whatever you pass as a parameter is converted to String and returned..

Otherwise, if you use Integer.toString(),Float.toString() etc.(i.e. SomeType.toString()) then you will have to check the datatype of parameter that you want to convert into string. So, its better to use String.valueOf() for such convertions.

If you are having an array of object class that contains different values like Integer,Char,Float etc. then by using String.valueOf() method you can convert the elements of such array into String form easily. On contrary, if you want to use SomeType.toString() then at first you will need to know about there their datatype classes(maybe by using "instanceOf" operator) and then only you can proceed for a typecast.

String.valueOf() method when called matches the parameter that is passed(whether its Integer,Char,Float etc.) and by using method overloading calls that "valueOf()" method whose parameter gets matched, and then inside that method their is a direct call to corresponding "toString()" method..

So, we can see how the overhead of checking datatype and then calling corresponding "toString()" method is removed.Only we need is to call String.valueOf() method, not caring about what we want to convert to String.

Conclusion: String.valueOf() method has its importance just at cost of one more call.

Counter exit code 139 when running, but gdb make it through

this error is also caused by null pointer reference. if you are using a pointer who is not initialized then it causes this error.

to check either a pointer is initialized or not you can try something like

Class *pointer = new Class();

Select query to remove non-numeric characters

You can create SQL CLR scalar function in order to be able to use regular expressions like replace patterns.

Here you can find example of how to create such function.

Having such function will solve the issue with just the following lines:

SELECT [dbo].[fn_Utils_RegexReplace] ('AB ABCDE # 123', '[^0-9]', '');
SELECT [dbo].[fn_Utils_RegexReplace] ('ABCDE# 123', '[^0-9]', '');
SELECT [dbo].[fn_Utils_RegexReplace] ('AB: ABC# 123', '[^0-9]', '');

More important, you will be able to solve more complex issues as the regular expressions will bring a whole new world of options directly in your T-SQL statements.

How to change the button text of <input type="file" />?

Hide the file input. Create a new input to capture a click event and forward it to the hidden input:

<input type="button" id="loadFileXml" value="loadXml" onclick="document.getElementById('file').click();" />
<input type="file" style="display:none;" id="file" name="file"/>

Replace specific text with a redacted version using Python

You can do it using named-entity recognition (NER). It's fairly simple and there are out-of-the-shelf tools out there to do it, such as spaCy.

NER is an NLP task where a neural network (or other method) is trained to detect certain entities, such as names, places, dates and organizations.


Sponge Bob went to South beach, he payed a ticket of $200!
I know, Michael is a good person, he goes to McDonalds, but donates to charity at St. Louis street.


NER with spacy

Just be aware that this is not 100%!

Here are a little snippet for you to try out:

import spacy

phrases = ['Sponge Bob went to South beach, he payed a ticket of $200!', 'I know, Michael is a good person, he goes to McDonalds, but donates to charity at St. Louis street.']
nlp = spacy.load('en')
for phrase in phrases:
   doc = nlp(phrase)
   replaced = ""
   for token in doc:
      if token in doc.ents:
         replaced+="XXXX "
         replaced+=token.text+" "

Read more here:

You could, instead of replacing with XXXX, replace based on the entity type, like:

if ent.label_ == "PERSON":
   replaced += "<PERSON> "


import re, random

personames = ["Jack", "Mike", "Bob", "Dylan"]

phrase = re.replace("<PERSON>", random.choice(personames), phrase)

How to view unallocated free space on a hard disk through terminal

I had just the same trouble with fedora 26 and LVM partitions, it seems I forgot check something during the installation, So, my 15G root directory has been increased to 227G like I needed.

I posted the steps I followed here:

resize2fs: Bad magic number in super-block while trying to open

0) #df -h

Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 1.9G     0  1.9G   0% /dev
tmpfs                    1.9G     0  1.9G   0% /dev/shm
tmpfs                    1.9G  824K  1.9G   1% /run
tmpfs                    1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mapper/fedora-root   15G  2.1G   13G  14% /
tmpfs                    1.9G     0  1.9G   0% /tmp
/dev/md126p1             976M  119M  790M  14% /boot
tmpfs                    388M     0  388M   0% /run/user/0

1) # vgs

  VG     #PV #LV #SN Attr   VSize   VFree   
  fedora   1   2   0 wz--n- 231.88g 212.96g

2) # vgdisplay

  --- Volume group ---
  VG Name               fedora
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                2
  Open LV               2
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               231.88 GiB
  PE Size               4.00 MiB
  Total PE              59361
  Alloc PE / Size       4844 / 18.92 GiB
  Free  PE / Size       54517 / 212.96 GiB
  VG UUID               9htamV-DveQ-Jiht-Yfth-OZp7-XUDC-tWh5Lv

3) # lvextend -l +100%FREE /dev/mapper/fedora-root

  Size of logical volume fedora/root changed from 15.00 GiB (3840 extents) to 227.96 GiB (58357 extents).
  Logical volume fedora/root successfully resized.

4) #lvdisplay

5) #fd -h

6) # xfs_growfs /dev/mapper/fedora-root

meta-data=/dev/mapper/fedora-root isize=512    agcount=4, agsize=983040 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=1 spinodes=0 rmapbt=0
         =                       reflink=0
data     =                       bsize=4096   blocks=3932160, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal               bsize=4096   blocks=2560, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
data blocks changed from 3932160 to 59757568

7) #df -h

Filesystem               Size  Used Avail Use% Mounted on
devtmpfs                 1.9G     0  1.9G   0% /dev
tmpfs                    1.9G     0  1.9G   0% /dev/shm
tmpfs                    1.9G  828K  1.9G   1% /run
tmpfs                    1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/mapper/fedora-root  228G  2.3G  226G   2% /
tmpfs                    1.9G     0  1.9G   0% /tmp
/dev/md126p1             976M  119M  790M  14% /boot
tmpfs                    388M     0  388M   0% /run/user/0

Best regards,

HTML: how to force links to open in a new tab, not new window

Since I fell into this old question and then found that it is now possible (maybe this css option wasn't available then), I just want to add an update on how it can be done:

<a href="[yourlink]" target="_blank" style="target-new: tab;">Google</a>

Here are the options for the target-new style:

target-new: window | tab | none 

Didn't test the none option, maybe it uses the default browser setting.

I confirmed this for Firefox and IE7-9.

Codeigniter displays a blank page instead of error messages

Another method is to see if you've surpassed the error checking in your code by accident. Search all your code for any instance of error_reporting(). If you call it without parameters, it just returns the current level, and is harmless. If you call it with a parameter, such as 0 (zero), it will turn off error reporting.

You can test for this in CodeIgnitor by looking at their core library under ../system/core/Common.php and finding a section that's at about line 615 that looks like:

if (($severity & error_reporting()) !== $severity)

Add something like:

if (($severity & error_reporting()) !== $severity)
   echo "Suppressing errors!";

and you should be able to trap for surpassed errors, and debug from there.

Initializing a struct to 0

I also thought this would work but it's misleading:

myStruct _m1 = {0};

When I tried this:

myStruct _m1 = {0xff};

Only the 1st byte was set to 0xff, the remaining ones were set to 0. So I wouldn't get into the habit of using this.

HTML5 Video // Completely Hide Controls

There are two ways to hide video tag controls

  1. Remove the controls attribute from the video tag.

  2. Add the css to the video tag

    video::-webkit-media-controls-panel {
    display: none !important;
    opacity: 1 !important;}

Objects inside objects in javascript

You may have as many levels of Object hierarchy as you want, as long you declare an Object as being a property of another parent Object. Pay attention to the commas on each level, that's the tricky part. Don't use commas after the last element on each level:

{el1, el2, {el31, el32, el33}, {el41, el42}}

var MainObj = {_x000D_
  prop1: "prop1MainObj",_x000D_
  Obj1: {_x000D_
    prop1: "prop1Obj1",_x000D_
    prop2: "prop2Obj1",    _x000D_
    Obj2: {_x000D_
      prop1: "hey you",_x000D_
      prop2: "prop2Obj2"_x000D_
  Obj3: {_x000D_
    prop1: "prop1Obj3",_x000D_
    prop2: "prop2Obj3"_x000D_
  Obj4: {_x000D_
    prop1: true,_x000D_
    prop2: 3_x000D_
  }  _x000D_

How do I do logging in C# without using 3rd party libraries?

I would rather not use any outside frameworks like

Why? Log4net would probably address most of your requirements. For example check this class: RollingFileAppender.

Log4net is well documented and there are thousand of resources and use cases on the web.

Factory Pattern. When to use factory methods?

UML from

enter image description here

Product: It defines an interface of the objects the Factory method creates.

ConcreteProduct: Implements Product interface

Creator: Declares the Factory method

ConcreateCreator: Implements the Factory method to return an instance of a ConcreteProduct

Problem statement: Create a Factory of Games by using Factory Methods, which defines the game interface.

Code snippet:

import java.util.HashMap;

/* Product interface as per UML diagram */
interface Game{
    /* createGame is a complex method, which executes a sequence of game steps */
    public void createGame();

/* ConcreteProduct implementation as per UML diagram */
class Chess implements Game{
    public Chess(){

    public void createGame(){
        System.out.println("Create Chess game");
        System.out.println("Define 64 blocks");
        System.out.println("Place 16 pieces for White opponent");
        System.out.println("Place 16 pieces for Black opponent");
        System.out.println("Start Chess game");
class Checkers implements Game{
    public Checkers(){

    public void createGame(){
        System.out.println("Create Checkers game");
        System.out.println("Opponents:2 or 3 or 4 or 6");
        System.out.println("For each opponent, place 10 coins");
        System.out.println("Start Checkers game");
class Ludo implements Game{
    public Ludo(){

    public void createGame(){
        System.out.println("Create Ludo game");
        System.out.println("Opponents:2 or 3 or 4");
        System.out.println("For each opponent, place 4 coins");
        System.out.println("Create two dices with numbers from 1-6");
        System.out.println("Start Ludo game");

/* Creator interface as per UML diagram */
interface IGameFactory {
    public Game getGame(String gameName);

/* ConcreteCreator implementation as per UML diagram */
class GameFactory implements IGameFactory {

     HashMap<String,Game> games = new HashMap<String,Game>();
        Since Game Creation is complex process, we don't want to create game using new operator every time.
        Instead we create Game only once and store it in Factory. When client request a specific game, 
        Game object is returned from Factory instead of creating new Game on the fly, which is time consuming

    public GameFactory(){

        games.put(Chess.class.getName(),new Chess());
        games.put(Checkers.class.getName(),new Checkers());
        games.put(Ludo.class.getName(),new Ludo());        
    public Game getGame(String gameName){
        return games.get(gameName);

public class NonStaticFactoryDemo{
    public static void main(String args[]){
        if ( args.length < 1){
            System.out.println("Usage: java FactoryDemo gameName");

        GameFactory factory = new GameFactory();
        Game game = factory.getGame(args[0]);
        if ( game != null ){                    
            System.out.println(args[0]+  " Game does not exists in factory");


java NonStaticFactoryDemo Chess
Create Chess game
Define 64 blocks
Place 16 pieces for White opponent
Place 16 pieces for Black opponent
Start Chess game

This example shows a Factory class by implementing a FactoryMethod.

  1. Game is the interface for all type of games. It defines complex method: createGame()

  2. Chess, Ludo, Checkers are different variants of games, which provide implementation to createGame()

  3. public Game getGame(String gameName) is FactoryMethod in IGameFactory class

  4. GameFactory pre-creates different type of games in constructor. It implements IGameFactory factory method.

  5. game Name is passed as command line argument to NotStaticFactoryDemo

  6. getGame in GameFactory accepts a game name and returns corresponding Game object.


Creates objects without exposing the instantiation logic to the client.


Define an interface for creating an object, but let the subclasses decide which class to instantiate. The Factory method lets a class defer instantiation to subclasses

Use case:

When to use: Client doesn't know what concrete classes it will be required to create at runtime, but just wants to get a class that will do the job.

Convert date to UTC using moment.js

This worked for me. Others might find it useful.

// date = 2020-08-31T00:00:00Z I'm located in Denmark (timezone is +2 hours)

moment.utc(moment(date).utc()).format() // returns 2020-08-30T22:00:00Z

Java: Array with loop

this is actually the summation of an arithmatic progression with common difference as 1. So this is a special case of sum of natural numbers. Its easy can be done with a single line of code.

int i = 100;
// Implement the fomrulae n*(n+1)/2
int sum = (i*(i+1))/2;

R Markdown - changing font size and font type in html output

To change the font size, you don't need to know a lot of html for this. Open the html output with notepad ++. Control F search for "font-size". You should see a section with font sizes for the headers (h1, h2, h3,...).

Add the following somewhere in this section.

body {
  font-size: 16px;

The font size above is 16 pt font. You can change the number to whatever you want.

Align Bootstrap Navigation to Center

.navbar-nav {
   float: left;
   margin: 0;
   margin-left: 40%;

.navbar-nav.navbar-right:last-child {
   margin-right: -15px;
   margin-left: 0;

Updated Fiddle

Since You Have used the float property we don't have many options except to adjust it manually.

How to create .ipa file using Xcode?

Archive process (using Xcode 8.3.2)

Note : If you are using creating IPA using drag-and-drop process using iTunes Mac app then this is no longer applicable for iTunes 12.7 since there is no built-in App store in iTunes 12.7.

  1. Select ‘Generic iOS Device’ on device list in Xcode

Step 1

  1. Clean the project (cmd + shift + k as shortcut)

Step 2

  1. Go to Product -> Archive your project

Step 3

  1. Once archive is succeeded this will open a window with archived project

  2. You can validate your archive by pressing Validate (optional step but recommended)

  3. Now press on Export button

Step 4 5 6

  1. This will open list of method for export. Select the export method as per your requirement and click on Next button.

Step 7

  1. This will show list of team for provisioning. Select accordingly and press on ‘Choose’ button.

Step 8

  1. Now you’ve to select Device support -> Export one app for all compatible devices (recommended). If you want IPA for specific device then select the device variant from list and press on ‘Next’ button.

Step 9

  1. Now you’ll be able to see the ‘Summary’ and then press on ‘Next’ button

Step 10

  1. Thereafter IPA file generation beings and later you’ll be able to export the IPA as [App Name - Date Time] and then press on ‘Done’.

Step 11

Can I write into the console in a unit test? If yes, why doesn't the console window open?

I have an easier solution (that I used myself recently, for a host of lazy reasons). Add this method to the class you are working in:

public static void DumbDebug(string message)
    File.WriteAllText(@"C:\AdHocConsole\" + message + ".txt", "this is really dumb. I wish Microsoft had more obvious solutions to its solutions problems.");
} up the directory AdHocConsole, and order by created time. Make sure when you add your 'print statements'. They are distinct though, else there will be juggling.

How to set a variable to current date and date-1 in linux?

You can try:

d=$(date +%Y-%m-%d)
echo "$d"

EDIT: Changed y to Y for 4 digit date as per QuantumFool's comment.

Get String in YYYYMMDD format from JS date object?

It seems that mootools provides Date().format():

I'm not sure if it worth including just for this particular task though.

Get folder name from full file path

You could use this:

string path = @"c:\projects\roott\wsdlproj\devlop\beta2\text";
string lastDirectory = path.Split(new char[] { System.IO.Path.DirectorySeparatorChar }, StringSplitOptions.RemoveEmptyEntries).Last();

Writing BMP image in pure c/c++ without other libraries

I just wanted to share an improved version of Minhas Kamal's code because although it worked well enough for most applications, I had a few issues with it still. Two highly important things to remember:

  1. The code (at the time of writing) calls free() on two static arrays. This will cause your program to crash. So I commented out those lines.
  2. NEVER assume that your pixel data's pitch is always (Width*BytesPerPixel). It's best to let the user specify the pitch value. Example: when manipulating resources in Direct3D, the RowPitch is never guaranteed to be an even multiple of the byte depth being used. This can cause errors in your generated bitmaps (especially at odd resolutions such as 1366x768).

Below, you can see my revisions to his code:

const int bytesPerPixel = 4; /// red, green, blue
const int fileHeaderSize = 14;
const int infoHeaderSize = 40;

void generateBitmapImage(unsigned char *image, int height, int width, int pitch, const char* imageFileName);
unsigned char* createBitmapFileHeader(int height, int width, int pitch, int paddingSize);
unsigned char* createBitmapInfoHeader(int height, int width);

void generateBitmapImage(unsigned char *image, int height, int width, int pitch, const char* imageFileName) {

    unsigned char padding[3] = { 0, 0, 0 };
    int paddingSize = (4 - (/*width*bytesPerPixel*/ pitch) % 4) % 4;

    unsigned char* fileHeader = createBitmapFileHeader(height, width, pitch, paddingSize);
    unsigned char* infoHeader = createBitmapInfoHeader(height, width);

    FILE* imageFile = fopen(imageFileName, "wb");

    fwrite(fileHeader, 1, fileHeaderSize, imageFile);
    fwrite(infoHeader, 1, infoHeaderSize, imageFile);

    int i;
    for (i = 0; i < height; i++) {
        fwrite(image + (i*pitch /*width*bytesPerPixel*/), bytesPerPixel, width, imageFile);
        fwrite(padding, 1, paddingSize, imageFile);


unsigned char* createBitmapFileHeader(int height, int width, int pitch, int paddingSize) {
    int fileSize = fileHeaderSize + infoHeaderSize + (/*bytesPerPixel*width*/pitch + paddingSize) * height;

    static unsigned char fileHeader[] = {
        0,0, /// signature
        0,0,0,0, /// image file size in bytes
        0,0,0,0, /// reserved
        0,0,0,0, /// start of pixel array

    fileHeader[0] = (unsigned char)('B');
    fileHeader[1] = (unsigned char)('M');
    fileHeader[2] = (unsigned char)(fileSize);
    fileHeader[3] = (unsigned char)(fileSize >> 8);
    fileHeader[4] = (unsigned char)(fileSize >> 16);
    fileHeader[5] = (unsigned char)(fileSize >> 24);
    fileHeader[10] = (unsigned char)(fileHeaderSize + infoHeaderSize);

    return fileHeader;

unsigned char* createBitmapInfoHeader(int height, int width) {
    static unsigned char infoHeader[] = {
        0,0,0,0, /// header size
        0,0,0,0, /// image width
        0,0,0,0, /// image height
        0,0, /// number of color planes
        0,0, /// bits per pixel
        0,0,0,0, /// compression
        0,0,0,0, /// image size
        0,0,0,0, /// horizontal resolution
        0,0,0,0, /// vertical resolution
        0,0,0,0, /// colors in color table
        0,0,0,0, /// important color count

    infoHeader[0] = (unsigned char)(infoHeaderSize);
    infoHeader[4] = (unsigned char)(width);
    infoHeader[5] = (unsigned char)(width >> 8);
    infoHeader[6] = (unsigned char)(width >> 16);
    infoHeader[7] = (unsigned char)(width >> 24);
    infoHeader[8] = (unsigned char)(height);
    infoHeader[9] = (unsigned char)(height >> 8);
    infoHeader[10] = (unsigned char)(height >> 16);
    infoHeader[11] = (unsigned char)(height >> 24);
    infoHeader[12] = (unsigned char)(1);
    infoHeader[14] = (unsigned char)(bytesPerPixel * 8);

    return infoHeader;

UIView Hide/Show with animation

This code give an animation like pushing viewController in uinavigation controller...

CATransition *animation = [CATransition animation];
 animation.type = kCATransitionPush;
 animation.subtype = kCATransitionFromRight;
 animation.duration = 0.3;
 [_viewAccountName.layer addAnimation:animation forKey:nil];

 _viewAccountName.hidden = true;

Used this for pop animation...

 CATransition *animation = [CATransition animation];
 animation.type = kCATransitionPush;
 animation.subtype = kCATransitionFromLeft;
 animation.duration = 0.3;
 [_viewAccountName.layer addAnimation:animation forKey:nil];

 _viewAccountName.hidden = false;

How can I get the behavior of GNU's readlink -f on a Mac?

readlink -f does two things:

  1. It iterates along a sequence of symlinks until it finds an actual file.
  2. It returns that file's canonicalized name—i.e., its absolute pathname.

If you want to, you can just build a shell script that uses vanilla readlink behavior to achieve the same thing. Here's an example. Obviously you could insert this in your own script where you'd like to call readlink -f



cd `dirname $TARGET_FILE`

# Iterate down a (possible) chain of symlinks
while [ -L "$TARGET_FILE" ]
    cd `dirname $TARGET_FILE`

# Compute the canonicalized name by finding the physical path 
# for the directory we're in and appending the target file.
PHYS_DIR=`pwd -P`
echo $RESULT

Note that this doesn't include any error handling. Of particular importance, it doesn't detect symlink cycles. A simple way to do this would be to count the number of times you go around the loop and fail if you hit an improbably large number, such as 1,000.

EDITED to use pwd -P instead of $PWD.

Note that this script expects to be called like ./script_name filename, no -f, change $1 to $2 if you want to be able to use with -f filename like GNU readlink.

Printing Mongo query output to a file while in the mongo shell

AFAIK, there is no a interactive option for output to file, there is a previous SO question related with this: Printing mongodb shell output to File

However, you can log all the shell session if you invoked the shell with tee command:

$ mongo | tee file.txt
MongoDB shell version: 2.4.2
connecting to: test
> printjson({this: 'is a test'})
{ "this" : "is a test" }
> printjson({this: 'is another test'})
{ "this" : "is another test" }
> exit

Then you'll get a file with this content:

MongoDB shell version: 2.4.2
connecting to: test
> printjson({this: 'is a test'})
{ "this" : "is a test" }
> printjson({this: 'is another test'})
{ "this" : "is another test" }
> exit

To remove all the commands and keep only the json output, you can use a command similar to:

tail -n +3 file.txt | egrep -v "^>|^bye" > output.json

Then you'll get:

{ "this" : "is a test" }
{ "this" : "is another test" }

Is it possible to get a list of files under a directory of a website? How?

There are only two ways to find a web page: through a link or by listing the directory.

Usually, web servers disable directory listing, so if there is really no link to the page, then it cannot be found.

BUT: information about the page may get out in ways you don't expect. For example, if a user with Google Toolbar visits your page, then Google may know about the page, and it can appear in its index. That will be a link to your page.

Rotate a div using javascript

To rotate a DIV we can add some CSS that, well, rotates the DIV using CSS transform rotate.

To toggle the rotation we can keep a flag, a simple variable with a boolean value that tells us what way to rotate.

var rotated = false;

document.getElementById('button').onclick = function() {
    var div = document.getElementById('div'),
        deg = rotated ? 0 : 66; = 'rotate('+deg+'deg)';    = 'rotate('+deg+'deg)';     = 'rotate('+deg+'deg)';      = 'rotate('+deg+'deg)';       = 'rotate('+deg+'deg)'; 

    rotated = !rotated;

var rotated = false;_x000D_
document.getElementById('button').onclick = function() {_x000D_
    var div = document.getElementById('div'),_x000D_
        deg = rotated ? 0 : 66;_x000D_
_x000D_ = 'rotate('+deg+'deg)'; _x000D_    = 'rotate('+deg+'deg)'; _x000D_     = 'rotate('+deg+'deg)'; _x000D_      = 'rotate('+deg+'deg)'; _x000D_       = 'rotate('+deg+'deg)'; _x000D_
    rotated = !rotated;_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

To add some animation to the rotation all we have to do is add CSS transitions

div {
    -webkit-transition: all 0.5s ease-in-out;
    -moz-transition: all 0.5s ease-in-out;
    -o-transition: all 0.5s ease-in-out;
    transition: all 0.5s ease-in-out;

var rotated = false;_x000D_
document.getElementById('button').onclick = function() {_x000D_
    var div = document.getElementById('div'),_x000D_
        deg = rotated ? 0 : 66;_x000D_
_x000D_ = 'rotate('+deg+'deg)'; _x000D_    = 'rotate('+deg+'deg)'; _x000D_     = 'rotate('+deg+'deg)'; _x000D_      = 'rotate('+deg+'deg)'; _x000D_       = 'rotate('+deg+'deg)'; _x000D_
    rotated = !rotated;_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
    -webkit-transition: all 0.5s ease-in-out;_x000D_
    -moz-transition: all 0.5s ease-in-out;_x000D_
    -o-transition: all 0.5s ease-in-out;_x000D_
    transition: all 0.5s ease-in-out;_x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

Another way to do it is using classes, and setting all the styles in a stylesheet, thus keeping them out of the javascript

document.getElementById('button').onclick = function() {

document.getElementById('button').onclick = function() {_x000D_
#div {_x000D_
    position:relative; _x000D_
    height: 200px; _x000D_
    width: 200px; _x000D_
    margin: 30px;_x000D_
    background: red;_x000D_
    -webkit-transition: all 0.5s ease-in-out;_x000D_
    -moz-transition: all 0.5s ease-in-out;_x000D_
    -o-transition: all 0.5s ease-in-out;_x000D_
    transition: all 0.5s ease-in-out;_x000D_
#div.rotated {_x000D_
    -webkit-transform : rotate(66deg); _x000D_
    -moz-transform : rotate(66deg); _x000D_
    -ms-transform : rotate(66deg); _x000D_
    -o-transform : rotate(66deg); _x000D_
    transform : rotate(66deg); _x000D_
<button id="button">rotate</button>_x000D_
<br /><br />_x000D_
<div id="div"></div>

npm WARN enoent ENOENT: no such file or directory, open 'C:\Users\Nuwanst\package.json'

Make sure you are on the right directory where you have package.json

What's NSLocalizedString equivalent in Swift?

A variation of the existing answers:

Swift 5.1:

extension String {

    func localized(withComment comment: String? = nil) -> String {
        return NSLocalizedString(self, comment: comment ?? "")


You can then simply use it with or without comment:

"Hello".localized(withComment: "Simple greeting")

Please note that genstrings won't work with this solution.

Visual Studio 2013 License Product Key

I solved this, without having to completely reinstall Visual Studio 2013.

For those who may come across this in the future, the following steps worked for me:

  1. Run the ISO (or vs_professional.exe).
  2. If you get the error below, you need to update the Windows Registry to trick the installer into thinking you still have the base version. If you don't get this error, skip to step 3 "The product version that you are trying to set up is earlier than the version already installed on this computer."

    • Click the link for 'examine the log file' and look near the bottom of the log, for this line: Detected related bundle ... operation: Downgrade

    • open regedit.exe and do an Edit > Find... for that GUID. In my case it was {6dff50d0-3bc3-4a92-b724-bf6d6a99de4f}. This was found in:


    • Edit the BundleVersion value and change it to a lower version. I changed mine from 12.0.21005.13 to 12.0.21000.13: BundleVersion for Visual Studio lower the version for BundleVersion

    • Exit the registry

  3. Run the ISO (or vs_professional.exe) again. If it has a repair button like the image below, you can skip to step 4.

    Visual Studio Repair button

    • Otherwise you have to let the installer fix the registry. I did this by "installing" at least one feature, even though I think I already had all features (they were not detected). This took about 20 minutes.
  4. Run the ISO (or vs_professional.exe) again. This time repair should be visible.

  5. Click Repair and let it update your installation and apply its embedded license key. This took about 20 minutes.

Now when you run Visual Studio 2013, it should indicate that a license key was applied, under Help > Register Product:

License: Product key applied

Hope this helps somebody in the future!

Reference blog 'story'

Convert a String to Modified Camel Case in Java or Title Case as is otherwise called


    static String toCamelCase(String s){
           String[] parts = s.split(" ");
           String camelCaseString = "";
           for (String part : parts){
               if(part!=null && part.trim().length()>0)
              camelCaseString = camelCaseString + toProperCase(part);
                   camelCaseString=camelCaseString+part+" ";   
           return camelCaseString;

        static String toProperCase(String s) {
            String temp=s.trim();
            String spaces="";
            int startCharIndex=s.charAt(temp.indexOf(0));
            temp=temp.substring(0, 1).toUpperCase() +
            spaces+temp.substring(1).toLowerCase()+" ";
            return temp;

  public static void main(String[] args) {
     String string="HI tHiS is   SomE Statement";

Java serialization - local class incompatible

This worked for me:

If you wrote your Serialized class object into a file, then made some changes to file and compiled it, and then you try to read an object, then this will happen.

So, write the necessary objects to file again if a class is modified and recompiled.

PS: This is NOT a solution; was meant to be a workaround.

Eclipse jump to closing brace

On the Macintosh, place the cursor after either the opening or closing curly brace } and use the keys: Shift + Command + P.


I had a similar issue where I wanted to represent HTML as JSON in the following way:

  • For HTML text nodes, use a string
  • For HTML elements, use an array with:
    • The (tag) name of the element
    • An object, mapping attribute keys to attribute values
    • The (inlined) list of children nodes




   ['span', {}, 'text'],

I wrote a function which handles transforming a DOM Element into this kind of JS structure. You can find this function at the end of this answer. The function is written in Typescript. You can use the Typescript playground to convert it to clean JavaScript.

Furthermore, if you need to parse an html string into DOM, assign to .innerHtml:

let element = document.createElement('div')
element.innerHtml = htmlString

Also, this one is common knowledge but if you need a JSON string output, use JSON.stringify.

 * A NodeDescriptor stands for either an (HTML) Element, or for a text node
export type NodeDescriptor = ElementDescriptor | string

 * Array representing an HTML Element. It consists of:
 * - The (tag) name of the element
 * - An object, mapping attribute keys to attribute values
 * - The (inlined) list of children nodes
export type ElementDescriptor = [
   Record<string, string>,

export let htmlToJs = (element: Element, trim = true): ElementDescriptor => {
   let convertElement = (element: Element): ElementDescriptor => {
      let attributeObject: Record<string, string> = {}
      for (let { name, value } of element.attributes) {
         attributeObject[name] = value

      let childArray: NodeDescriptor[] = []
      for (let node of element.childNodes) {
         let converter = htmlToJsDispatch[node.nodeType]
         if (converter) {
            let descriptor = converter(node as any)
            let skip = false

            if (trim && typeof descriptor === 'string') {
               descriptor = descriptor.trim()
               if (descriptor === '') skip = true

            if (!skip) childArray.push(descriptor)

      return [element.tagName.toLowerCase(), attributeObject, ...childArray]

   let htmlToJsDispatch = {
      [element.ELEMENT_NODE]: convertElement,
      [element.TEXT_NODE]: (node: Text): string =>,

   return convertElement(element)

Convert pyQt UI to python

For pyqt5 you can use

pyuic5 xyz.ui > 


pyuic5 xyz.ui -o

jQuery hover and class selector

Your code looks fine to me.

Make sure the DOM is ready before your javascript is executed by using jQuery's $(callback) function:

$(function() {
   $('.menuItem').hover( function(){
      $(this).css('background-color', '#F00');
      $(this).css('background-color', '#000');

What is the purpose of willSet and didSet in Swift?

My understanding is that set and get are for computed properties (no backing from stored properties)

if you are coming from an Objective-C bare in mind that the naming conventions have changed. In Swift an iVar or instance variable is named stored property

Example 1 (read only property) - with warning:

var test : Int {
    get {
        return test

This will result in a warning because this results in a recursive function call (the getter calls itself).The warning in this case is "Attempting to modify 'test' within its own getter".

Example 2. Conditional read/write - with warning

var test : Int {
    get {
        return test
    set (aNewValue) {
        //I've contrived some condition on which this property can be set
        //(prevents same value being set)
        if (aNewValue != test) {
            test = aNewValue

Similar problem - you cannot do this as it's recursively calling the setter. Also, note this code will not complain about no initialisers as there is no stored property to initialise.

Example 3. read/write computed property - with backing store

Here is a pattern that allows conditional setting of an actual stored property

//True model data
var _test : Int = 0

var test : Int {
    get {
        return _test
    set (aNewValue) {
        //I've contrived some condition on which this property can be set
        if (aNewValue != test) {
            _test = aNewValue

Note The actual data is called _test (although it could be any data or combination of data) Note also the need to provide an initial value (alternatively you need to use an init method) because _test is actually an instance variable

Example 4. Using will and did set

//True model data
var _test : Int = 0 {

    //First this
    willSet {
        println("Old value is \(_test), new value is \(newValue)")

    //value is set

    //Finaly this
    didSet {
        println("Old value is \(oldValue), new value is \(_test)")

var test : Int {
    get {
        return _test
    set (aNewValue) {
        //I've contrived some condition on which this property can be set
        if (aNewValue != test) {
            _test = aNewValue

Here we see willSet and didSet intercepting a change in an actual stored property. This is useful for sending notifications, synchronisation etc... (see example below)

Example 5. Concrete Example - ViewController Container

//Underlying instance variable (would ideally be private)
var _childVC : UIViewController? {
    willSet {
        //REMOVE OLD VC
        println("Property will set")
        if (_childVC != nil) {
            self.setOverrideTraitCollection(nil, forChildViewController: _childVC)
        if (newValue) {


    //I can't see a way to 'stop' the value being set to the same controller - hence the computed property

    didSet {
        //ADD NEW VC
        println("Property did set")
        if (_childVC) {
//                var views  = NSDictionaryOfVariableBindings(self.view)    .. NOT YET SUPPORTED (NSDictionary bridging not yet available)

            //Add subviews + constraints
            _childVC!.view.setTranslatesAutoresizingMaskIntoConstraints(false)       //For now - until I add my own constraints
            let views = ["view" : _childVC!.view] as NSMutableDictionary
            let layoutOpts = NSLayoutFormatOptions(0)
            let lc1 : AnyObject[] = NSLayoutConstraint.constraintsWithVisualFormat("|[view]|",  options: layoutOpts, metrics: NSDictionary(), views: views)
            let lc2 : AnyObject[] = NSLayoutConstraint.constraintsWithVisualFormat("V:|[view]|", options: layoutOpts, metrics: NSDictionary(), views: views)

            //Forward messages to child

//Computed property - this is the property that must be used to prevent setting the same value twice
//unless there is another way of doing this?
var childVC : UIViewController? {
    get {
        return _childVC
    set(suggestedVC) {
        if (suggestedVC != _childVC) {
            _childVC = suggestedVC

Note the use of BOTH computed and stored properties. I've used a computed property to prevent setting the same value twice (to avoid bad things happening!); I've used willSet and didSet to forward notifications to viewControllers (see UIViewController documentation and info on viewController containers)

I hope this helps, and please someone shout if I've made a mistake anywhere here!

How to detect scroll position of page using jQuery

$(window).scroll( function() { 
 var scrolled_val = $(document).scrollTop().valueOf();
 alert(scrolled_val+ ' = scroll value');

This is another way of getting the value of scroll.

Override console.log(); for production

It would be super useful to be able to toggle logging in the production build. The code below turns the logger off by default.

When I need to see logs, I just type debug(true) into the console.

var consoleHolder = console;
function debug(bool){
        consoleHolder = console;
        console = {};
            console[key] = function(){};
        console = consoleHolder;

To be thorough, this overrides ALL of the console methods, not just console.log.

Disabling vertical scrolling in UIScrollView

From iOS11 one can use the following property

let frameLayoutGuide: UILayoutGuide

If you set constraints for frameLayoutGuide.topAnchor and frameLayoutGuide.bottomAnchor to the same anchors of some subview of your scrollView then vertical scroll will be disabled and the height of the scrollView will be equal to the height of its subview.

git stash apply version

Since version 2.11, it's pretty easy, you can use the N stack number instead of saying "stash@{n}". So now instead of using:

git stash apply "stash@{n}"

You can type:

git stash apply n

For example, in your list:

stash@{0}: WIP on design: f2c0c72... Adjust Password Recover Email
stash@{1}: WIP on design: f2c0c72... Adjust Password Recover Email
stash@{2}: WIP on design: eb65635... Email Adjust
stash@{3}: WIP on design: eb65635... Email Adjust

If you want to apply stash@{1} you could type:

git stash apply 1

Otherwise, you can use it even if you have some changes in your directory since, but you must be sure the stash won't overwrite your working directory changes if it does you'll get an error:

error: Your local changes to the following files would be overwritten by merge:
Please commit your changes or stash them before you merge.

In versions prior to, it refused to work if there was a change in the working directory.

Git release notes:

The user always has to say "stash@{$N}" when naming a single element in the default location of the stash, i.e. reflogs in refs/stash. The "git stash" command learned to accept "git stash apply 4" as a short-hand for "git stash apply stash@{4}"

git stash apply" used to refuse to work if there was any change in the working tree, even when the change did not overlap with the change the stash recorded

Android AlertDialog Single Button

In Mono for Android you can do this:

var ad = new AlertDialog.Builder(this);
ad.SetPositiveButton("OK", delegate { ad.Dispose(); });

Get the value of input text when enter key pressed

Something like this (not tested, but should work)

Pass this as parameter in Html:

<input type="text" placeholder="some text" class="search" onkeydown="search(this)"/>

And alert the value of the parameter passed into the search function:

function search(e){

C++ error: "Array must be initialized with a brace enclosed initializer"

The syntax to statically initialize an array uses curly braces, like this:

int array[10] = { 0 };

This will zero-initialize the array.

For multi-dimensional arrays, you need nested curly braces, like this:

int cipher[Array_size][Array_size]= { { 0 } };

Note that Array_size must be a compile-time constant for this to work. If Array_size is not known at compile-time, you must use dynamic initialization. (Preferably, an std::vector).

how to stop a running script in Matlab

MATLAB doesn't respond to Ctrl-C while executing a mex implemented function such as svd. Also when MATLAB is allocating big chunk of memory it doesn't respond. A good practice is to always run your functions for small amount of data, and when all test passes run it for actual scale. When time is an issue, you would want to analyze how much time each segment of code runs as well as their rough time complexity.

What is the best way to search the Long datatype within an Oracle database?


create table longtable(id number,text long);

insert into longtable values(1,'hello world');
insert into longtable values(2,'say hello!');


create or replace function search_long(r rowid) return varchar2 is
temporary_varchar varchar2(4000);
select text into temporary_varchar from longtable where rowid=r;
return temporary_varchar;

SQL> select text from longtable where search_long(rowid) like '%hello%';                                                                              

hello world
say hello!

But be careful. A PL/SQL function will only search the first 32K of LONG.

String formatting: % vs. .format vs. string literal

But please be careful, just now I've discovered one issue when trying to replace all % with .format in existing code: '{}'.format(unicode_string) will try to encode unicode_string and will probably fail.

Just look at this Python interactive session log:

Python 2.7.2 (default, Aug 27 2012, 19:52:55) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2
; s='?'
; u=u'?'
; s
; u

s is just a string (called 'byte array' in Python3) and u is a Unicode string (called 'string' in Python3):

; '%s' % s
; '%s' % u

When you give a Unicode object as a parameter to % operator it will produce a Unicode string even if the original string wasn't Unicode:

; '{}'.format(s)
; '{}'.format(u)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
UnicodeEncodeError: 'latin-1' codec can't encode character u'\u0439' in position 0: ordinal not in range(256)

but the .format function will raise "UnicodeEncodeError":

; u'{}'.format(s)
; u'{}'.format(u)

and it will work with a Unicode argument fine only if the original string was Unicode.

; '{}'.format(u'i')

or if argument string can be converted to a string (so called 'byte array')

How to force file download with PHP

That's all you need. "Monkey.gif" change to your file name. If you need to download from other server, "monkey.gif" change to ""

Get parent directory of running script

I hope this will help

function get_directory(){
    $s = empty($_SERVER["HTTPS"]) ? '' : ($_SERVER["HTTPS"] == "on") ? "s" : "";
    $protocol = substr(strtolower($_SERVER["SERVER_PROTOCOL"]), 0, strpos(strtolower($_SERVER["SERVER_PROTOCOL"]), "/")) . $s;
    $port = ($_SERVER["SERVER_PORT"] == "80") ? "" : (":".$_SERVER["SERVER_PORT"]);
return $protocol . "://" . $_SERVER['SERVER_NAME'] . dirname($_SERVER['PHP_SELF']);
define("ROOT_PATH", get_directory()."/" );

Switch tabs using Selenium WebDriver with Java

This will work for the MacOS for Firefox and Chrome:

// opens the default browser tab with the first webpage
driver.get("the url 1");

// opens the second tab
driver.findElement(By.cssSelector("Body")).sendKeys(Keys.COMMAND + "t");
driver.get("the url 2");

// comes back to the first tab
driver.findElement(By.cssSelector("Body")).sendKeys(Keys.COMMAND, Keys.SHIFT, "{");

How to center a "position: absolute" element

If you don't know the width of the element you can use this code:

<div style="position: absolute; left: 50%;">
    <div style="position: relative; left: -50%; border: dotted red 1px;">
        I am some centered shrink-to-fit content! <br />
        tum te tum

Demo at fiddle:


Pretty-print a Map in Java

String result = objectMapper.writeValueAsString(map) - as simple as this!


{"2019-07-04T03:00":1,"2019-07-04T04:00":1,"2019-07-04T01:00":1,"2019-07-04T02:00":1,"2019-07-04T13:00":1,"2019-07-04T06:00":1 ...}

P.S. add Jackson JSON to your classpath.

How can I clear the Scanner buffer in Java?

You can't explicitly clear Scanner's buffer. Internally, it may clear the buffer after a token is read, but that's an implementation detail outside of the porgrammers' reach.

Min and max value of input in angular4 application

Simply do this in angular2+ by adding (onkeypress)

<input type="number" 
    (onkeypress)="return (event.charCode == 8 || event.charCode == 0) ? null : event.charCode >= 48 && event.charCode <= 57"

Tested on Angular 7

SQLSTATE[HY000] [1045] Access denied for user 'username'@'localhost' using CakePHP

I want to add to the answers posted on above that none of the solutions proposed here worked for me. My WAMP, is working on port 3308 instead of 3306 which is what it is installed by default. I found out that when working in a local environment, if you are using mysqladmin in your computer (for testing environment), and if you are working with port other than 3306, you must define your variable DB_SERVER with the value localhost:NumberOfThePort, so it will look like the following: define("DB_SERVER", "localhost:3308"). You can obtain this value by right-clicking on the WAMP icon in your taskbar (on the hidden icons section) and select Tools. You will see the section: "Port used by MySQL: NumberOfThePort"

This will fix your connection to your database.

This was the error I got: Error: SQLSTATE[HY1045] Access denied for user 'username'@'localhost' on line X.

I hope this helps you out.


MySQL Update Inner Join tables query

For MySql WorkBench, Please use below :

update emp as a
inner join department b on
where a.emp_id in (10,11,12); 

How would you make a comma-separated string from a list of strings?

Here is a alternative solution in Python 3.0 which allows non-string list items:

>>> alist = ['a', 1, (2, 'b')]
  • a standard way

    >>> ", ".join(map(str, alist))
    "a, 1, (2, 'b')"
  • the alternative solution

    >>> import io
    >>> s = io.StringIO()
    >>> print(*alist, file=s, sep=', ', end='')
    >>> s.getvalue()
    "a, 1, (2, 'b')"

NOTE: The space after comma is intentional.

How to change a nullable column to not nullable in a Rails migration?

You can't use add_timestamps and null:false if you have existing records, so here is the solution :

def change
  add_timestamps(:buttons, null: true)

  Button.find_each { |b| b.update(created_at:, updated_at: }

  change_column_null(:buttons, :created_at, false)
  change_column_null(:buttons, :updated_at, false)

Emulating a do-while loop in Bash

This implementation:

  • Has no code duplication
  • Doesn't require extra functions()
  • Doesn't depend on the return value of code in the "while" section of the loop:
while $do || conditions; do
  # your code ...

It works with a read loop, too, skipping the first read:

while $do || read foo; do

  # your code ...
  echo $foo

How to check if a file exists before creating a new file

Looked around a bit, and the only thing I find is using the open system call. It is the only function I found that allows you to create a file in a way that will fail if it already exists

#include <fcntl.h>
#include <errno.h>

int fd=open(filename, O_WRONLY | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (fd < 0) {
  /* file exists or otherwise uncreatable
     you might want to check errno*/
}else {
  /* File is open to writing */

Note that you have to give permissions since you are creating a file.

This also removes any race conditions there might be

Can I call a base class's virtual function if I'm overriding it?

If there are multiple levels of inheritance, you can specify the direct base class, even if the actual implementation is at a lower level.

class Foo
  virtual void DoStuff ()

class Bar : public Foo

class Baz : public Bar
  void DoStuff ()
    Bar::DoStuff() ;

In this example, the class Baz specifies Bar::DoStuff() although the class Bar does not contain an implementation of DoStuff. That is a detail, which Baz does not need to know.

It is clearly a better practice to call Bar::DoStuff than Foo::DoStuff, in case a later version of Bar also overrides this method.

mysql error 2005 - Unknown MySQL server host 'localhost'(11001)

ERROR 2005 (HY000): Unknown MySQL server host 'localhost' (0)

modify list of host names for your system:


Make sure that you have the following entry: localhost
In my case that entry was localhost which caussed all problem

(you may need to change modify permission to modify this file)

This performs DNS resolution of host “localhost” to the IP address

Checking during array iteration, if the current element is the last element

This always does the trick for me

foreach($array as $key => $value) {
   if (end(array_keys($array)) == $key)
       // Last key reached

Edit 30/04/15

$last_key = end(array_keys($array));

foreach($array as $key => $value) {
  if ( $key == $last_key)
      // Last key reached

To avoid the E_STRICT warning mentioned by @Warren Sergent

$array_keys = array_keys($array);
$last_key = end($array_keys);

Printing Exception Message in java

The output looks correct to me:

Invalid JavaScript code: missing } after property list (<Unknown source>) in <Unknown source>; at line number 1

I think Invalid Javascript code: .. is the start of the exception message.

Normally the stacktrace isn't returned with the message:

try {
    throw new RuntimeException("hu?\ntrace-line1\ntrace-line2");
} catch (Exception e) {
    System.out.println(e.getMessage()); // prints "hu?"

So maybe the code you are calling catches an exception and rethrows a ScriptException. In this case maybe e.getCause().getMessage() can help you.

Getting json body in aws Lambda via API gateway

You may have forgotten to define the Content-Type header. For example:

  return {
    statusCode: 200,
    headers: {
      'Content-Type': 'application/json',
    body: JSON.stringify({ items }),

'names' attribute must be the same length as the vector

In the spirit of @Chris W, just try to replicate the exact error you are getting. An example would have helped but maybe you're doing:

  x <- c(1,2)
  y <- c("a","b","c")
  names(x) <- y

Error in names(x) <- y : 
  'names' attribute [3] must be the same length as the vector [2]

I suspect you're trying to give names to a vector (x) that is shorter than your vector of names (y).

Reading a plain text file in Java

Here are the three working and tested methods:

Using BufferedReader

package io;
public class ReadFromFile2 {
    public static void main(String[] args)throws Exception {
        File file = new File("C:\\Users\\pankaj\\Desktop\\");
        BufferedReader br = new BufferedReader(new FileReader(file));
        String st;
        while((st=br.readLine()) != null){

Using Scanner

package io;

import java.util.Scanner;

public class ReadFromFileUsingScanner {
    public static void main(String[] args) throws Exception {
        File file = new File("C:\\Users\\pankaj\\Desktop\\");
        Scanner sc = new Scanner(file);

Using FileReader

package io;
public class ReadingFromFile {

    public static void main(String[] args) throws Exception {
        FileReader fr = new FileReader("C:\\Users\\pankaj\\Desktop\\");
        int i;
        while (( != -1){
            System.out.print((char) i);

Read the entire file without a loop using the Scanner class

package io;

import java.util.Scanner;

public class ReadingEntireFileWithoutLoop {

    public static void main(String[] args) throws FileNotFoundException {
        File file = new File("C:\\Users\\pankaj\\Desktop\\");
        Scanner sc = new Scanner(file);

What is the difference between Release and Debug modes in Visual Studio?

Debug and Release are just labels for different solution configurations. You can add others if you want. A project I once worked on had one called "Debug Internal" which was used to turn on the in-house editing features of the application. You can see this if you go to Configuration Manager... (it's on the Build menu). You can find more information on MSDN Library under Configuration Manager Dialog Box.

Each solution configuration then consists of a bunch of project configurations. Again, these are just labels, this time for a collection of settings for your project. For example, our C++ library projects have project configurations called "Debug", "Debug_Unicode", "Debug_MT", etc.

The available settings depend on what type of project you're building. For a .NET project, it's a fairly small set: #defines and a few other things. For a C++ project, you get a much bigger variety of things to tweak.

In general, though, you'll use "Debug" when you want your project to be built with the optimiser turned off, and when you want full debugging/symbol information included in your build (in the .PDB file, usually). You'll use "Release" when you want the optimiser turned on, and when you don't want full debugging information included.

How to for each the hashmap?


HashMap<String, HashMap<SomeInnerKeyType, String>> selects =
    new HashMap<String, HashMap<SomeInnerKeyType, String>>();


for(HashMap<SomeInnerKeyType, String> h : selects.values())
   ComboBox cb = new ComboBox();
   for(String s : h.values())

Displaying tooltip on mouse hover of a text

As there is nothing in this question (but its age) that requires a solution in Windows.Forms, here is a way to do this in WPF in code-behind.

TextBlock tb = new TextBlock();
tb.Inlines.Add(new Run("Background indicates packet repeat status:"));
tb.Inlines.Add(new LineBreak());
tb.Inlines.Add(new LineBreak());
Run r = new Run("White");
r.Background = Brushes.White;
r.ToolTip = "This word has a White background";
tb.Inlines.Add(new Run("\t= Identical Packet received at this time."));
tb.Inlines.Add(new LineBreak());
r = new Run("SkyBlue");
r.ToolTip = "This word has a SkyBlue background";
r.Background = new SolidColorBrush(Colors.SkyBlue);
tb.Inlines.Add(new Run("\t= Original Packet received at this time."));

myControl.Content = tb;

adb uninstall failed

Seems like you have an app that contains a hidden Device Administrator like this one here:

you can only uninstall such an app when you disable the device admin first. You can use to disable it or do it by your own by sending the intent to the app that invokes the receiver that will disable the device admin.

Android "elevation" not showing a shadow

Setting android:clipToPadding="false" in the top relative layout has solved the problem.

catch specific HTTP error in python

Tims answer seems to me as misleading. Especially when urllib2 does not return expected code. For example this Error will be fatal (believe or not - it is not uncommon one when downloading urls):

AttributeError: 'URLError' object has no attribute 'code'

Fast, but maybe not the best solution would be code using nested try/except block:

import urllib2
    urllib2.urlopen("some url")
except urllib2.HTTPError, err:
        if err.code == 404:
            # Handle the error

More information to the topic of nested try/except blocks Are nested try/except blocks in python a good programming practice?

How to write macro for Notepad++?

My personal experience is that shortcuts.xml is overwritten with the initially loaded + later recorded macros and settings when Notepad++ exits. So you can't use Notepad++ itself for editing this file.

Close Notepad++, edit shortcuts.xml by another tool, save it and restart Notepad++.

Determine Whether Two Date Ranges Overlap

All the solutions that check a multitude of conditions based on where the ranges are in relation to one another can be greatly simplified by just ensuring that a specific range starts earlier! You ensure that the first range starts earlier (or at the same time) by swapping the ranges if necessary up front.

Then, you can detect overlap if the other range start is less than or equal to the first range end (if ranges are inclusive, containing both the start and end times) or less than (if ranges are inclusive of start and exclusive of end).

Assuming inclusive at both ends, there's only four possibilities of which one is a non-overlap:

|----------------------|        range 1
|--->                           range 2 overlap
 |--->                          range 2 overlap
                       |--->    range 2 overlap
                        |--->   range 2 no overlap

The endpoint of the range 2 doesn't enter into it. So, in pseudo-code:

def doesOverlap (r1, r2):
    if r1.s > r2.s:
        swap r1, r2
    if r2.s > r1.e:
        return false
    return true

This could be simplified even more into:

def doesOverlap (r1, r2):
    if r1.s > r2.s:
        swap r1, r2
    return r2.s <= r1.e

If the ranges are inclusive at the start and exclusive at the end, you just have to replace > with >= in the second if statement (for the first code segment: in the second code segment, you'd use < rather than <=):

|----------------------|        range 1
|--->                           range 2 overlap
 |--->                          range 2 overlap
                       |--->    range 2 no overlap
                        |--->   range 2 no overlap

You greatly limit the number of checks you have to make because you remove half of the problem space early by ensuring range 1 never starts after range 2.

Converting byte array to String (Java)

The byte array contains characters in a special encoding (that you should know). The way to convert it to a String is:

String decoded = new String(bytes, "UTF-8");  // example for one encoding type

By The Way - the raw bytes appear may appear as negative decimals just because the java datatype byte is signed, it covers the range from -128 to 127.

-109 = 0x93: Control Code "Set Transmit State"

The value (-109) is a non-printable control character in UNICODE. So UTF-8 is not the correct encoding for that character stream.

0x93 in "Windows-1252" is the "smart quote" that you're looking for, so the Java name of that encoding is "Cp1252". The next line provides a test code:

System.out.println(new String(new byte[]{-109}, "Cp1252")); 

Calculate execution time of a SQL query?

I found this one more helpful and simple

DECLARE @StartTime datetime,@EndTime datetime   
--Your Query to be run goes here--  
SELECT DATEDIFF(ms,@StartTime,@EndTime) AS [Duration in milliseconds]   

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"

How to create a file in Linux from terminal window?

Depending on what you want the file to contain:

  • touch /path/to/file for an empty file
  • somecommand > /path/to/file for a file containing the output of some command.

      eg: grep --help > randomtext.txt
          echo "This is some text" > randomtext.txt
  • nano /path/to/file or vi /path/to/file (or any other editor emacs,gedit etc)
    It either opens the existing one for editing or creates & opens the empty file to enter, if it doesn't exist

Create the file using cat

$ cat > myfile.txt

Now, just type whatever you want in the file:

Hello World!

CTRL-D to save and exit

There are several possible solutions:

Create an empty file

touch file


echo -n > file

printf '' > file

The echo version will work only if your version of echo supports the -n switch to suppress newlines. This is a non-standard addition. The other examples will all work in a POSIX shell.

Create a file containing a newline and nothing else

echo '' > file

printf '\n' > file

This is a valid "text file" because it ends in a newline.

Write text into a file

"$EDITOR" file

echo 'text' > file

cat > file <<END \

printf 'text\n' > file

These are equivalent. The $EDITOR command assumes that you have an interactive text editor defined in the EDITOR environment variable and that you interactively enter equivalent text. The cat version presumes a literal newline after the \ and after each other line. Other than that these will all work in a POSIX shell.

Of course there are many other methods of writing and creating files, too.

Get day of week using NSDate

The simple answer (swift 3):

Calendar.current.component(.weekday, from: Date())

No increment operator (++) in Ruby?

From a posting by Matz:

(1) ++ and -- are NOT reserved operator in Ruby.

(2) C's increment/decrement operators are in fact hidden assignment. They affect variables, not objects. You cannot accomplish assignment via method. Ruby uses +=/-= operator instead.

(3) self cannot be a target of assignment. In addition, altering the value of integer 1 might cause severe confusion throughout the program.


Razor View Engine : An expression tree may not contain a dynamic operation

Seems like your view is typed dynamic. Set the right type on the view and you'll see the error go away.

Splitting a string into separate variables

Try this:

$Object = 'FirstPart SecondPart' | ConvertFrom-String -PropertyNames Val1, Val2

How do I prevent site scraping?

You can't stop normal screen scraping. For better or worse, it's the nature of the web.

You can make it so no one can access certain things (including music files) unless they're logged in as a registered user. It's not too difficult to do in Apache. I assume it wouldn't be too difficult to do in IIS as well.

typecast string to integer - Postgres

Common issue

Naively type casting any string into an integer like so

SELECT ''::integer

Often results to the famous error:

Query failed: ERROR: invalid input syntax for integer: ""


PostgreSQL has no pre-defined function for safely type casting any string into an integer.


Create a user-defined function inspired by PHP's intval() function.

CREATE FUNCTION intval(character varying) RETURNS integer AS $$

    WHEN length(btrim(regexp_replace($1, '[^0-9]', '','g')))>0 THEN btrim(regexp_replace($1, '[^0-9]', '','g'))::integer
    ELSE 0
END AS intval;



/* Example 1 */
SELECT intval('9000');
-- output: 9000

/* Example 2 */
SELECT intval('9gag');
-- output: 9

/* Example 3 */
SELECT intval('the quick brown fox jumps over the lazy dog');
-- output: 0

GitHub: invalid username or password

I am getting this while cloning app from bitbucket:

Cloning into 'YourAppName'...
Password for 'https://youruser id': 
remote: Invalid username or password

I solved it. Here you need to create password for your userid

  1. Click on Your profile and settings Click on Your profile and settings

  2. Then Create app password choose your name password will generated ,paste that password to terminal Create app password

Make absolute positioned div expand parent div height

Absolute views position themselves against the nearest ancestor that isn't statically positioned (position: static), therefore if you want an absolute view positioned against a given parent, set the parent position to relative and the child to position to absolute

sqlplus: error while loading shared libraries: cannot open shared object file: No such file or directory

You should already have all needed variables in /etc/profile.d/ Make sure you source it:

$ source /etc/profile.d/

The file's content looks like:

export PATH

If you don't have it, create it and source it.

How do I download a tarball from GitHub using cURL?

Use the -L option to follow redirects:

curl -L | tar zx

Set CSS property in Javascript?

All of the answers tell you correctly how to do what you asked but I would advise using JavaScript to set a class on the element and style it by using CSS. That way you are keeping the correct separation between behaviour and style.

Imagine if you got a designer in to re-style the site... they should be able to work purely in CSS without having to work with your JavaScript.

In prototype I would do:


Android TabLayout Android Design

I've just managed to setup new TabLayout, so here are the quick steps to do this (????)?*:???

  1. Add dependencies inside your build.gradle file:

    dependencies {
        compile ''
  2. Add TabLayout inside your layout

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android=""
  3. Setup your Activity like this:

    import android.os.Bundle;
    public class TabLayoutActivity extends AppCompatActivity {
        protected void onCreate(Bundle savedInstanceState) {
            Toolbar toolbar = (Toolbar) findViewById(;
            TabLayout tabLayout = (TabLayout) findViewById(;
            ViewPager viewPager = (ViewPager) findViewById(;
            if (toolbar != null) {
            viewPager.setAdapter(new SectionPagerAdapter(getSupportFragmentManager()));
        public class SectionPagerAdapter extends FragmentPagerAdapter {
            public SectionPagerAdapter(FragmentManager fm) {
            public Fragment getItem(int position) {
                switch (position) {
                    case 0:
                        return new FirstTabFragment();
                    case 1:
                        return new SecondTabFragment();
            public int getCount() {
                return 2;
            public CharSequence getPageTitle(int position) {
                switch (position) {
                    case 0:
                        return "First Tab";
                    case 1:
                        return "Second Tab";

XMLHttpRequest cannot load an URL with jQuery

I am using WebAPI 3 and was facing the same issue. The issue has resolve as @Rytis added his solution. And I think in WebAPI 3, we don't need to define method RegisterWebApi.

My change was only in web.config file and is working.

 <add name="Access-Control-Allow-Origin" value="*" />
 <add name="Access-Control-Allow-Methods" value="GET, POST" />

Thanks for you solution @Rytis!

Using the "With Clause" SQL Server 2008

There are two types of WITH clauses:

Here is the FizzBuzz in SQL form, using a WITH common table expression (CTE).

;WITH mil AS (
 SELECT TOP 1000000 ROW_NUMBER() OVER ( ORDER BY c.column_id ) [n]
 FROM master.sys.all_columns as c
 CROSS JOIN master.sys.all_columns as c2
             CASE WHEN n  % 5 = 0 THEN 'FizzBuzz' ELSE 'Fizz' END
        WHEN n % 5 = 0 THEN 'Buzz'
        ELSE CAST(n AS char(6))
     END + CHAR(13)
 FROM mil

Here is a select statement also using a WITH clause

SELECT * FROM orders WITH (NOLOCK) where order_id = 123

How do I decode a string with escaped unicode?

Edit (2017-10-12):

@MechaLynx and @Kevin-Weber note that unescape() is deprecated from non-browser environments and does not exist in TypeScript. decodeURIComponent is a drop-in replacement. For broader compatibility, use the below instead:

> ''

Original answer:

> ''

You can offload all the work to JSON.parse

How can I solve Exception in thread "main" java.lang.NullPointerException error

This is the problem

double a[] = null;

Since a is null, NullPointerException will arise every time you use it until you initialize it. So this:

a[i] = var;

will fail.

A possible solution would be initialize it when declaring it:

double a[] = new double[PUT_A_LENGTH_HERE]; //seems like this constant should be 7

IMO more important than solving this exception, is the fact that you should learn to read the stacktrace and understand what it says, so you could detect the problems and solve it.


This exception means there's a variable with null value being used. How to solve? Just make sure the variable is not null before being used.

at twoten.TwoTenB.(

This line has two parts:

  • First, shows the class and method where the error was thrown. In this case, it was at <init> method in class TwoTenB declared in package twoten. When you encounter an error message with SomeClassName.<init>, means the error was thrown while creating a new instance of the class e.g. executing the constructor (in this case that seems to be the problem).
  • Secondly, shows the file and line number location where the error is thrown, which is between parenthesis. This way is easier to spot where the error arose. So you have to look into file, line number 29. This seems to be a[i] = var;.

From this line, other lines will be similar to tell you where the error arose. So when reading this:

at javapractice.JavaPractice.main(

It means that you were trying to instantiate a TwoTenB object reference inside the main method of your class JavaPractice declared in javapractice package.

How to store date/time and timestamps in UTC time zone with JPA and Hibernate

With Spring Boot JPA, use the below code in your file and obviously you can modify timezone to your choice = UTC

Then in your Entity class file,

private LocalDateTime created;

Response to preflight request doesn't pass access control check

JavaScript XMLHttpRequest and Fetch follow the same-origin policy. So, a web application using XMLHttpRequest or Fetch could only make HTTP requests to its own domain.


You have to send the Access-Control-Allow-Origin: * HTTP header from your server side.

If you are using Apache as your HTTP server then you can add it to your Apache configuration file like this:

<IfModule mod_headers.c>
    Header set Access-Control-Allow-Origin "*"

Mod_headers is enabled by default in Apache, however, you may want to ensure it's enabled by running:

 a2enmod headers

How to get row count in sqlite using Android?

Change your getTaskCount Method to this:

public int getTaskCount(long tasklist_id){
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor= db.rawQuery("SELECT COUNT (*) FROM " + TABLE_TODOTASK + " WHERE " + KEY_TASK_TASKLISTID + "=?", new String[] { String.valueOf(tasklist_id) });
    int count= cursor.getInt(0);
    return count;

Then, update the click handler accordingly:

public void onItemClick(AdapterView<?> arg0, android.view.View v, int position, long id) {
    db = new TodoTask_Database(getApplicationContext());

    // Get task list id
    int tasklistid = adapter.getItem(position).getTaskListId();

    if(db.getTaskCount(tasklistid) > 0) {    
        Intent taskListID = new Intent(getApplicationContext(), AddTask_List.class);
        taskListID.putExtra("TaskList_ID", tasklistid);
    } else {
        Intent addTask = new Intent(getApplicationContext(), Add_Task.class);

What is a serialVersionUID and why should I use it?

You can tell Eclipse to ignore these serialVersionUID warnings:

Window > Preferences > Java > Compiler > Errors / Warnings > Potential Programming Problems

In case you didn't know, there are a lot of other warnings you can enable in this section (or even have some reported as errors), many are very useful:

  • Potential Programming Problems: Possible accidental boolean assignment
  • Potential Programming Problems: Null pointer access
  • Unnecessary code: Local variable is never read
  • Unnecessary code: Redundant null check
  • Unnecessary code: Unnecessary cast or 'instanceof'

and many more.

Python convert csv to xlsx

There is a simple way

import os
import csv
import sys

from openpyxl import Workbook


if __name__ == '__main__':
    workbook = Workbook()
    worksheet =
    with open('input.csv', 'r') as f:
        reader = csv.reader(f)
        for r, row in enumerate(reader):
            for c, col in enumerate(row):
                for idx, val in enumerate(col.split(',')):
                    cell = worksheet.cell(row=r+1, column=c+1)
                    cell.value = val'output.xlsx')

Get the latest record with filter in Django

You can do comparison with this down here.


latest('created') is same as order_by('-created').first() Please correct me if I am wrong

Convert all first letter to upper case, rest lower for each word

When building big tables speed is a concern so Jamie Dixon's second function is best, but it doesn't completely work as is...

It fails to take all of the letters to lowercase, and it only capitalizes the first letter of the string, not the first letter of each word in the string... the below option fixes both issues:

    public string UppercaseFirstEach(string s)
        char[] a = s.ToLower().ToCharArray();

        for (int i = 0; i < a.Count(); i++ )
            a[i] = i == 0 || a[i-1] == ' ' ? char.ToUpper(a[i]) : a[i];


        return new string(a);

Although at this point, whether this is still the fastest option is uncertain, the Regex solution provided by George Mauer might be faster... someone who cares enough should test it.

How to check all versions of python installed on osx and centos


yum list installed
command to find the packages you installed.

Using ng-click vs bind within link function of Angular Directive

You may use a controller in directive:

angular.module('app', [])
  .directive('appClick', function(){
     return {
       restrict: 'A',
       scope: true,
       template: '<button ng-click="click()">Click me</button> Clicked {{clicked}} times',
       controller: function($scope, $element){
         $scope.clicked = 0;
         $ = function(){

Demo on plunkr

More about directives in Angular guide. And very helpfull for me was videos from official Angular blog post About those directives.

Fail to create Android virtual Device, "No system image installed for this Target"

As a workaround, go to sdk installation directory and perform the following steps:

  • Navigate to system-images/android-19/default
  • Move everything in there to system-images/android-19/

The directory structure should look like this: enter image description here

And it should work!

Unable to load script.Make sure you are either running a Metro server or that your bundle '' is packaged correctly for release

For me this problem started with upgrading react-native. The upgrade was necessary to add 64-bit support.

Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
Xcode: Not Found
Android Studio: 3.4 AI-183.6156.11.34.5692245

Packages: (wanted => installed)
react: 16.0.0-alpha.12 => 16.0.0-alpha.12
react-native: ~0.55.2 => 0.55.4
react-native-cli: 2.0.1

React Native Environment Info:
Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
Android SDK:
API Levels: 23, 26, 27, 28
Build Tools: 27.0.3, 28.0.3
System Images: android-28 | Google APIs Intel x86 Atom
Android Studio: 3.4 AI-183.6156.11.34.5692245
Xcode: /undefined - /usr/bin/xcodebuild
react: ^16.8.6 => 16.9.0 
react-native: 0.59.9 => 0.59.9 
create-react-native-app: 2.0.2
react-native-cli: 2.0.1

Also, One important change that I made for the upgrade was in ../android/build/build.gradle

android {
    defaultConfig {
        targetSdkVersion 28

I had to change the targetSdkVersion from 27 to 28 following warning when I tried to upload the build(.apk) to goole play console. Little did i realise that this was the root cause of the above error for me. Immediatly answers by @tom and @tinmarfrutos made absolute sense.

I solved the problem by adding android:usesCleartextTraffic="true" to my android/app/src/debug/AndroidManifest.xml

YouTube Autoplay not working

Remove the spaces before the autoplay=1:


Java SSL: how to disable hostname verification

I also had the same problem while accessing RESTful web services. And I their with the below code to overcome the issue:

public class Test {
    //Bypassing the SSL verification to execute our code successfully 
    static {

    public static void main(String[] args) {    
        //Access HTTPS URL and do something    
    //Method used for bypassing SSL verification
    public static void disableSSLVerification() {

        TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager() {
            public[] getAcceptedIssuers() {
                return null;

            public void checkClientTrusted(X509Certificate[] certs, String authType) {

            public void checkServerTrusted(X509Certificate[] certs, String authType) {

        } };

        SSLContext sc = null;
        try {
            sc = SSLContext.getInstance("SSL");
            sc.init(null, trustAllCerts, new;
        } catch (KeyManagementException e) {
        } catch (NoSuchAlgorithmException e) {

        HostnameVerifier allHostsValid = new HostnameVerifier() {
            public boolean verify(String hostname, SSLSession session) {
                return true;

It worked for me. try it!!

Vue.js data-bind style backgroundImage not working

I tried @david answer, and it didn't fix my issue. after a lot of hassle, I made a method and return the image with style string.


<div v-for="slide in loadSliderImages" :key="">
    <div v-else :style="bannerBgImage(slide.banner)"></div>


    return 'background-image: url("' + image + '")';

Delete a row in DataGridView Control in VB.NET

Assuming you are using Windows forms, you could allow the user to select a row and in the delete key click event. It is recommended that you allow the user to select 1 row only and not a group of rows (myDataGridView.MultiSelect = false)

Private Sub pbtnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click

        If myDataGridView.SelectedRows.Count > 0 Then
            'you may want to add a confirmation message, and if the user confirms delete
            MessageBox.Show("Select 1 row before you hit Delete")
        End If

    End Sub

Note that this will not delete the row form the database until you perform the delete in the database.

Get an object's class name at runtime

I know I'm late to the party, but I find that this works too.

var constructorString: string = this.constructor.toString();
var className: string = constructorString.match(/\w+/g)[1]; 


var className: string = this.constructor.toString().match(/\w+/g)[1];

The above code gets the entire constructor code as a string and applies a regex to get all 'words'. The first word should be 'function' and the second word should be the name of the class.

Hope this helps.