Programs & Examples On #Nonsequential

Error: No module named psycopg2.extensions

In python 3.4, while in a virtual environment, make sure you have the build dependencies first:

sudo apt-get build-dep python3-psycopg2

Then install it:

pip install psycopg2 

Slidedown and slideup layout with animation

This doesn't work for me, I want to to like jquery slideUp / slideDown function, I tried this code, but it only move the content wich stay at the same place after animation end, the view should have a 0dp height at start of slideDown and the view height (with wrap_content) after the end of the animation.

Twitter Bootstrap 3.0 how do I "badge badge-important" now

Another possible way, in order to make the colors a bit more intense, is this one:

<span class="badge progress-bar-info">10</span>
<span class="badge progress-bar-success">20</span>
<span class="badge progress-bar-warning">30</span>
<span class="badge progress-bar-danger">40</span>

See Bootply

How to count occurrences of a column value efficiently in SQL?

and if data in "age" column has similar records (i.e. many people are 25 years old, many others are 32 and so on), it causes confusion in aligning right count to each student. in order to avoid it, I joined the tables on student ID as well.

SELECT, S.age, C.cnt
FROM Students S 
INNER JOIN (SELECT id, age, count(age) as cnt  FROM Students GROUP BY student,age) 
C ON S.age = C.age *AND =*

Any shortcut to initialize all array elements to zero?

How it Reduces the Performance of your application....? Read Following.

In Java Language Specification the Default / Initial Value for any Object can be given as Follows.

For type byte, the default value is zero, that is, the value of (byte) is 0.

For type short, the default value is zero, that is, the value of (short) is 0.

For type int, the default value is zero, that is, 0.

For type long, the default value is zero, that is, 0L.

For type float, the default value is positive zero, that is, 0.0f.

For type double, the default value is positive zero, that is, 0.0d.

For type char, the default value is the null character, that is, '\u0000'.

For type boolean, the default value is false.

For all reference types, the default value is null.

By Considering all this you don't need to initialize with zero values for the array elements because by default all array elements are 0 for int array.

Because An array is a container object that holds a fixed number of values of a single type. Now the Type of array for you is int so consider the default value for all array elements will be automatically 0 Because it is holding int type.

Now consider the array for String type so that all array elements has default value is null.

Why don't do that......?

you can assign null value by using loop as you suggest in your Question.

int arr[] = new int[10];
for(int i=0;i<arr.length;i++)
    arr[i] = 0;

But if you do so then it will an useless loss of machine cycle. and if you use in your application where you have many arrays and you do that for each array then it will affect the Application Performance up-to considerable level.

The more use of machine cycle ==> More time to Process the data ==> Output time will be significantly increase. so that your application data processing can be considered as a low level(Slow up-to some Level).

How To Add An "a href" Link To A "div"?

try to implement with javascript this:

<div id="mydiv" onclick="myhref('');" >some stuff </div>
<script type="text/javascript">
    function myhref(web){
      window.location.href = web;}

java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.Config

By default, Tomcat container doesn’t contain any jstl library. To fix it, declares jstl.jar in your Maven pom.xml file if you are working in Maven project or add it to your application's classpath


Should I use Java's String.format() if performance is important?

I wrote a small class to test which has the better performance of the two and + comes ahead of format. by a factor of 5 to 6. Try it your self

import java.util.Date;

public class StringTest{

    public static void main( String[] args ){
    int i = 0;
    long prev_time = System.currentTimeMillis();
    long time;

    for( i = 0; i< 100000; i++){
        String s = "Blah" + i + "Blah";
    time = System.currentTimeMillis() - prev_time;

    System.out.println("Time after for loop " + time);

    prev_time = System.currentTimeMillis();
    for( i = 0; i<100000; i++){
        String s = String.format("Blah %d Blah", i);
    time = System.currentTimeMillis() - prev_time;
    System.out.println("Time after for loop " + time);


Running the above for different N shows that both behave linearly, but String.format is 5-30 times slower.

The reason is that in the current implementation String.format first parses the input with regular expressions and then fills in the parameters. Concatenation with plus, on the other hand, gets optimized by javac (not by the JIT) and uses StringBuilder.append directly.

Runtime comparison

Division of integers in Java

In Java
Integer/Integer = Integer
Integer/Double = Double//Either of numerator or denominator must be floating point number
1/10 = 0
1.0/10 = 0.1
1/10.0 = 0.1

Just type cast either of them.

symfony2 twig path with parameter url creation

 * @Route("/category/{id}", name="_category")
 * @Route("/category/{id}/{active}", name="_be_activatecategory")
 * @Template()
public function categoryAction($id, $active = null)
{ .. }

May works.

How do I use spaces in the Command Prompt?

I prefer to enclose the command in () which is valid batch which makes it a bit easier to read:

cmd /C ("C:\Program Files (x86)\WinRar\Rar.exe" a "D:\Hello 2\File.rar" "D:\Hello 2\*.*")

How to style input and submit button with CSS?

When styling a input type submit use the following code.

   input[type=submit] {
    background-color: pink; //Example stlying

c# razor url parameter from view

If you're doing the check inside the View, put the value in the ViewBag.

In your controller:

ViewBag["parameterName"] = Request["parameterName"];

It's worth noting that the Request and Response properties are exposed by the Controller class. They have the same semantics as HttpRequest and HttpResponse.

How to use BOOLEAN type in SELECT statement

From documentation:

You cannot insert the values TRUE and FALSE into a database column. You cannot select or fetch column values into a BOOLEAN variable. Functions called from a SQL query cannot take any BOOLEAN parameters. Neither can built-in SQL functions such as TO_CHAR; to represent BOOLEAN values in output, you must use IF-THEN or CASE constructs to translate BOOLEANvalues into some other type, such as 0 or 1, 'Y' or 'N', 'true' or 'false', and so on.

You will need to make a wrapper function that takes an SQL datatype and use it instead.


In Windows, you can change it through the registry:

; Set the TIME_WAIT delay to 30 seconds (0x1E)


JUnit Eclipse Plugin?

JUnit is part of Eclipse Java Development Tools (JDT). So, either install the JDT via Software Updates or download and install Eclipse IDE for Java Developers (actually, I'd recommend installing Eclipse IDE for Java EE Developers if you want a complete built-in environment for server side development).

You add it to a project by right clicking the project in the Package Explorer and selecting Build Path -> Add Libraries... Then simply select JUnit and click Next >.

Alter column in SQL Server

I think you want this syntax:

ALTER TABLE tb_TableName  
add constraint cnt_Record_Status Default '' for Record_Status

Based on some of your comments, I am going to guess that you might already have null values in your table which is causing the alter of the column to not null to fail. If that is the case, then you should run an UPDATE first. Your script will be:

update tb_TableName
set Record_Status  = ''
where Record_Status is null

ALTER TABLE tb_TableName

ALTER TABLE tb_TableName

See SQL Fiddle with demo

Entity Framework (EF) Code First Cascade Delete for One-to-Zero-or-One relationship

This code worked for me

protected override void OnModelCreating(DbModelBuilder modelBuilder)
            .HasRequired(d => d.User)
            .WithOptional(u => u.UserDetail)

The migration code was:

public override void Up()
        AddForeignKey("UserDetail", "UserId", "User", "UserId", cascadeDelete: true);

And it worked fine. When I first used

    .HasOptional(a => a.UserDetail)

The migration code was:

AddForeignKey("User", "UserDetail_UserId", "UserDetail", "UserId", cascadeDelete: true); 

but it does not match any of the two overloads available (in EntityFramework 6)

Best practices when running Node.js with port 80 (Ubuntu / Linode)

For port 80 (which was the original question), Daniel is exactly right. I recently moved to https and had to switch from iptables to a light nginx proxy managing the SSL certs. I found a useful answer along with a gist by gabrielhpugliese on how to handle that. Basically I

Hopefully that can save someone else some headaches. I'm sure there's a pure-node way of doing this, but nginx was quick and it worked.

If WorkSheet("wsName") Exists

Another version of the function without error handling. This time it is not case sensitive and a little bit more efficient.

Function WorksheetExists(wsName As String) As Boolean
    Dim ws As Worksheet
    Dim ret As Boolean        
    wsName = UCase(wsName)
    For Each ws In ThisWorkbook.Sheets
        If UCase(ws.Name) = wsName Then
            ret = True
            Exit For
        End If
    WorksheetExists = ret
End Function

What's the best way to add a drop shadow to my UIView

Try this:

UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRect:view.bounds];
view.layer.masksToBounds = NO;
view.layer.shadowColor = [UIColor blackColor].CGColor;
view.layer.shadowOffset = CGSizeMake(0.0f, 5.0f);
view.layer.shadowOpacity = 0.5f;
view.layer.shadowPath = shadowPath.CGPath;

First of all: The UIBezierPath used as shadowPath is crucial. If you don't use it, you might not notice a difference at first, but the keen eye will observe a certain lag occurring during events like rotating the device and/or similar. It's an important performance tweak.

Regarding your issue specifically: The important line is view.layer.masksToBounds = NO. It disables the clipping of the view's layer's sublayers that extend further than the view's bounds.

For those wondering what the difference between masksToBounds (on the layer) and the view's own clipToBounds property is: There isn't really any. Toggling one will have an effect on the other. Just a different level of abstraction.

Swift 2.2:

override func layoutSubviews()

    let shadowPath = UIBezierPath(rect: bounds)
    layer.masksToBounds = false
    layer.shadowColor = UIColor.blackColor().CGColor
    layer.shadowOffset = CGSizeMake(0.0, 5.0)
    layer.shadowOpacity = 0.5
    layer.shadowPath = shadowPath.CGPath

Swift 3:

override func layoutSubviews()

    let shadowPath = UIBezierPath(rect: bounds)
    layer.masksToBounds = false
    layer.shadowColor =
    layer.shadowOffset = CGSize(width: 0.0, height: 5.0)
    layer.shadowOpacity = 0.5
    layer.shadowPath = shadowPath.cgPath

CSS: styled a checkbox to look like a button, is there a hover?

it looks like you need a rule very similar to your checked rule

#ck-button input:hover + span {

and for hover and clicked state:

#ck-button input:checked:hover + span {

the order is important though.

Combine several images horizontally with Python

Edit: DTing's answer is more applicable to your question since it uses PIL, but I'll leave this up in case you want to know how to do it in numpy.

Here is a numpy/matplotlib solution that should work for N images (only color images) of any size/shape.

import numpy as np
import matplotlib.pyplot as plt

def concat_images(imga, imgb):
    Combines two color image ndarrays side-by-side.
    ha,wa = imga.shape[:2]
    hb,wb = imgb.shape[:2]
    max_height = np.max([ha, hb])
    total_width = wa+wb
    new_img = np.zeros(shape=(max_height, total_width, 3))
    return new_img

def concat_n_images(image_path_list):
    Combines N color images from a list of image paths.
    output = None
    for i, img_path in enumerate(image_path_list):
        img = plt.imread(img_path)[:,:,:3]
        if i==0:
            output = img
            output = concat_images(output, img)
    return output

Here is example use:

>>> images = ["ronda.jpeg", "rhod.jpeg", "ronda.jpeg", "rhod.jpeg"]
>>> output = concat_n_images(images)
>>> import matplotlib.pyplot as plt
>>> plt.imshow(output)

enter image description here

Running Java Program from Command Line Linux

If your Main class is in a package called FileManagement, then try:

java -cp . FileManagement.Main

in the parent folder of the FileManagement folder.

If your Main class is not in a package (the default package) then cd to the FileManagement folder and try:

java -cp . Main

More info about the CLASSPATH and how the JRE find classes:

Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_u64 on Intel CPUs

I can't give an authoritative answer, but provide an overview of a likely cause. This reference shows pretty clearly that for the instructions in the body of your loop there is a 3:1 ratio between latency and throughput. It also shows the effects of multiple dispatch. Since there are (give-or-take) three integer units in modern x86 processors, it's generally possible to dispatch three instructions per cycle.

So between peak pipeline and multiple dispatch performance and failure of these mechanisms, we have a factor of six in performance. It's pretty well known that the complexity of the x86 instruction set makes it quite easy for quirky breakage to occur. The document above has a great example:

The Pentium 4 performance for 64-bit right shifts is really poor. 64-bit left shift as well as all 32-bit shifts have acceptable performance. It appears that the data path from the upper 32 bits to the lower 32 bit of the ALU is not well designed.

I personally ran into a strange case where a hot loop ran considerably slower on a specific core of a four-core chip (AMD if I recall). We actually got better performance on a map-reduce calculation by turning that core off.

Here my guess is contention for integer units: that the popcnt, loop counter, and address calculations can all just barely run at full speed with the 32-bit wide counter, but the 64-bit counter causes contention and pipeline stalls. Since there are only about 12 cycles total, potentially 4 cycles with multiple dispatch, per loop body execution, a single stall could reasonably affect run time by a factor of 2.

The change induced by using a static variable, which I'm guessing just causes a minor reordering of instructions, is another clue that the 32-bit code is at some tipping point for contention.

I know this is not a rigorous analysis, but it is a plausible explanation.

Floating Div Over An Image

you might consider using the Relative and Absolute positining.

`.container {  
position: relative;  
.tag {     
position: absolute;   

I have tested it there, also if you want it to change its position use this as its margin:

top: 20px;
left: 10px;

It will place it 20 pixels from top and 10 pixels from left; but leave this one if not necessary.

How to include header files in GCC search path?

Try gcc -c -I/home/me/development/skia sample.c.

Insert current date/time using now() in a field using MySQL/PHP

NOW() normally works in SQL statements and returns the date and time. Check if your database field has the correct type (datetime). Otherwise, you can always use the PHP date() function and insert:

date('Y-m-d H:i:s')

But I wouldn't recommend this.

jQuery change event on dropdown

You should've kept that DOM ready function

$(function() {
    $("#projectKey").change(function() {
        alert( $('option:selected', this).text() );

The document isn't ready if you added the javascript before the elements in the DOM, you have to either use a DOM ready function or add the javascript after the elements, the usual place is right before the </body> tag

editing PATH variable on mac

environment.plst file loads first on MAC so put the path on it.

For 1st time use, use the following command

export PATH=$PATH: /path/to/set

How to save username and password with Mercurial?

While it may or may not work in your situation, I have found it useful to generate a public / private key using Putty's Pageant.

If you are also working with bitbucket (.org) it should give you the ability to provide a public key to your user account and then commands that reach out to the repository will be secured automatically.

If Pageant doesn't start up for you upon a reboot, you can add a shortcut to Pageant to your Windows "Start menu" and the shortcut may need to have a 'properties' populated with the location of your private (.ppk) file.

With this in place Mercurial and your local repositories will need to be set up to push/pull using the SSH format.

Here are some detailed instructions on Atlassian's site for Windows OR Mac/Linux.

You don't have to take my word for it and there are no doubt other ways to do it. Perhaps these steps described here are more for you:

  1. Start PuttyGen from Start -> PuTTY-> PuttyGen
  2. Generate a new key and save it as a .ppk file without a passphrase
  3. Use Putty to login to the server you want to connect to
  4. Append the Public Key text from PuttyGen to the text of ~/.ssh/authorized_keys
  5. Create a shortcut to your .ppk file from Start -> Putty to Start -> Startup
  6. Select the .ppk shortcut from the Startup menu (this will happen automatically at every startup)
  7. See the Pageant icon in the system tray? Right-click it and select “New session”
  8. Enter username@hostname in the “Host name” field
  9. You will now log in automatically.

How to push to History in React Router v4?

React router V4 now allows the history prop to be used as below:


The value then can be accessed wherever the location prop is available as state:{value} not component state.

How to cut first n and last n columns?

Try the following:

echo a#b#c | awk -F"#" '{$1 = ""; $NF = ""; print}' OFS=""

How can I run multiple curl requests processed sequentially?

Write a script with two curl requests in desired order and run it by cron, like


Setting environment variable in react-native?

In my opinion the best option is to use react-native-config. It supports 12 factor.

I found this package extremely useful. You can set multiple environments, e.g. development, staging, production.

In case of Android, variables are available also in Java classes, gradle, AndroidManifest.xml etc. In case of iOS, variables are available also in Obj-C classes, Info.plist.

You just create files like

  • .env.development
  • .env.staging
  • .env.production

You fill these files with key, values like


and then just use it:

import Config from 'react-native-config'

Config.API_URL  // ''
Config.GOOGLE_MAPS_API_KEY  // 'abcdefgh'

If you want to use different environments, you basically set ENVFILE variable like this:

ENVFILE=.env.staging react-native run-android

or for assembling app for production (android in my case):

cd android && ENVFILE=.env.production ./gradlew assembleRelease

Coerce multiple columns to factors at once

Choose some columns to coerce to factors:

cols <- c("A", "C", "D", "H")

Use lapply() to coerce and replace the chosen columns:

data[cols] <- lapply(data[cols], factor)  ## as.factor() could also be used

Check the result:

sapply(data, class)
#        A         B         C         D         E         F         G 
# "factor" "integer"  "factor"  "factor" "integer" "integer" "integer" 
#        H         I         J 
# "factor" "integer" "integer" 

Return outside function error in Python

It basically occours when you return from a loop you can only return from function

Circular dependency in Spring

The Spring reference manual explains how circular dependencies are resolved. The beans are instantiated first, then injected into each other.

Consider this class:

package mypackage;

public class A {

    public A() {
        System.out.println("Creating instance of A");

    private B b;

    public void setB(B b) {
        System.out.println("Setting property b of A instance");
        this.b = b;


And a similar class B:

package mypackage;

public class B {

    public B() {
        System.out.println("Creating instance of B");

    private A a;

    public void setA(A a) {
        System.out.println("Setting property a of B instance");
        this.a = a;


If you then had this configuration file:

<bean id="a" class="mypackage.A">
    <property name="b" ref="b" />

<bean id="b" class="mypackage.B">
    <property name="a" ref="a" />

You would see the following output when creating a context using this configuration:

Creating instance of A
Creating instance of B
Setting property a of B instance
Setting property b of A instance

Note that when a is injected into b, a is not yet fully initialised.

C++ floating point to integer type conversions

One thing I want to add. Sometimes, there can be precision loss. You may want to add some epsilon value first before converting. Not sure why that works... but it work.

int someint = (somedouble+epsilon);

How to debug a referenced dll (having pdb)

The following solution worked for me. It involves copy pasting the .dll and .pdb files properly from project A to B:

Declaring abstract method in TypeScript

I believe that using a combination of interfaces and base classes could work for you. It will enforce behavioral requirements at compile time (rq_ post "below" refers to a post above, which is not this one).

The interface sets the behavioral API that isn't met by the base class. You will not be able to set base class methods to call on methods defined in the interface (because you will not be able to implement that interface in the base class without having to define those behaviors). Maybe someone can come up with a safe trick to allow calling of the interface methods in the parent.

You have to remember to extend and implement in the class you will instantiate. It satisfies concerns about defining runtime-fail code. You also won't even be able to call the methods that would puke if you haven't implemented the interface (such as if you try to instantiate the Animal class). I tried having the interface extend the BaseAnimal below, but it hid the constructor and the 'name' field of BaseAnimal from Snake. If I had been able to do that, the use of a module and exports could have prevented accidental direct instantiation of the BaseAnimal class.

Paste this in here to see if it works for you:

// The behavioral interface also needs to extend base for substitutability
interface AbstractAnimal extends BaseAnimal {
    // encapsulates animal behaviors that must be implemented
    makeSound(input : string): string;

class BaseAnimal {
    constructor(public name) { }

    move(meters) {
        alert( + " moved " + meters + "m.");

// If concrete class doesn't extend both, it cannot use super methods.
class Snake extends BaseAnimal implements AbstractAnimal {
    constructor(name) { super(name); }
    makeSound(input : string): string {
        var utterance = "sssss"+input;
        return utterance;
    move() {

var longMover = new Snake("windy man");

longMover.makeSound(" I nothing?");

var fulture = new BaseAnimal("bob fossil");
// compile error on makeSound() because it is not defined.
// fulture.makeSound("you know, like a...")

I came across FristvanCampen's answer as linked below. He says abstract classes are an anti-pattern, and suggests that one instantiate base 'abstract' classes using an injected instance of an implementing class. This is fair, but there are counter arguments made. Read for yourself:

Part 2: I had another case where I wanted an abstract class, but I was prevented from using my solution above, because the defined methods in the "abstract class" needed to refer to the methods defined in the matching interface. So, I tool FristvanCampen's advice, sort of. I have the incomplete "abstract" class, with method implementations. I have the interface with the unimplemented methods; this interface extends the "abstract" class. I then have a class that extends the first and implements the second (it must extend both because the super constructor is inaccessible otherwise). See the (non-runnable) sample below:

export class OntologyConceptFilter extends FilterWidget.FilterWidget<ConceptGraph.Node, ConceptGraph.Link> implements FilterWidget.IFilterWidget<ConceptGraph.Node, ConceptGraph.Link> {

    subMenuTitle = "Ontologies Rendered"; // overload or overshadow?

        public conceptGraph: ConceptGraph.ConceptGraph,
        graphView: PathToRoot.ConceptPathsToRoot,
        implementation: FilterWidget.IFilterWidget<ConceptGraph.Node, ConceptGraph.Link>
        this.implementation = this;


export class FilterWidget<N extends GraphView.BaseNode, L extends GraphView.BaseLink<GraphView.BaseNode>> {

    public implementation: IFilterWidget<N, L>

    filterContainer: JQuery;

    public subMenuTitle : string; // Given value in children

        public graphView: GraphView.GraphView<N, L>


    doStuff(node: N){


export interface IFilterWidget<N extends GraphView.BaseNode, L extends GraphView.BaseLink<GraphView.BaseNode>> extends FilterWidget<N, L> {

    generateStuff(node: N): string;


Microsoft.ACE.OLEDB.12.0 is not registered

I installed the "Microsoft Access Database Engine 2010 Redistributable" as mentioned above and got side-tracked troubleshooting bitness issues when it seemed to be a version issue.

Installing "2007 Office System Driver: Data Connectivity Components" sorted it for me.

Open firewall port on CentOS 7

If you are familiar with iptables service like in centos 6 or earlier, you can still use iptables service by manual installation:

step 1 => install epel repo

yum install epel-release

step 2 => install iptables service

yum install iptables-services

step 3 => stop firewalld service

systemctl stop firewalld

step 4 => disable firewalld service on startup

systemctl disable firewalld

step 5 => start iptables service

systemctl start iptables

step 6 => enable iptables on startup

systemctl enable iptables

finally you're now can editing your iptables config at /etc/sysconfig/iptables.

So -> edit rule -> reload/restart.

do like older centos with same function like firewalld.

Select * from subquery

You can select every column from that sub-query by aliasing it and adding the alias before the *:

SELECT t.*, a+b AS total_sum
   SELECT SUM(column1) AS a, SUM(column2) AS b
   FROM table
) t

What is the syntax for Typescript arrow functions with generics?

The language specification says on p.64f

A construct of the form < T > ( ... ) => { ... } could be parsed as an arrow function expression with a type parameter or a type assertion applied to an arrow function with no type parameter. It is resolved as the former[..]


// helper function needed because Backbone-couchdb's sync does not return a jqxhr
let fetched = <
           R extends Backbone.Collection<any> >(c:R) => {
               return new Promise(function (fulfill, reject) {
                   c.fetch({reset: true, success: fulfill, error: reject})

"The Controls collection cannot be modified because the control contains code blocks"

I had this problem, but not via the Header. My placeholder was in the body. So I replaced all the <%= with <%# and did

protected void Page_Load(object sender, EventArgs e)

and it worked.

PDO mysql: How to know if insert was successful

You can test the rowcount

    $sqlStatement->execute( ...);
    if ($sqlStatement->rowCount() > 0)
        return true;

Long press on UITableView

Just add UILongPressGestureRecognizer to the given prototype cell in storyboard, then pull the gesture to the viewController's .m file to create an action method. I made it as I said.

Firebase cloud messaging notification not received by device

I faced the same problem but I had still had some debris in my manifest from the old GCM. When I took the following permission out of my manifest it fixed the error.

Check if at least two out of three booleans are true

The simplest way (IMO) that is not confusing and easy to read:

// Three booleans, check if two or more are true

return ( a && ( b || c ) ) || ( b && c );

jquery how to empty input field

if you hit the "back" button it usually tends to stick, what you can do is when the form is submitted clear the element then before it goes to the next page but after doing with the element what you need to.

                payment = 0;
                gtotal = ($('#shares').val() * 1) + payment;
                gtotal = gtotal.toFixed(2);
                $("").html("Total Payment: <strong>" + gtotal + "</strong>");

android:layout_height 50% of the screen size

best way is use

layout_height="0dp" layout_weight="0.5"

for example

    android:layout_weight="0.5" />

    android:text="TextView" />

WebView,TextView have 50% of the screen height

Is there a RegExp.escape function in JavaScript?

Nothing should prevent you from just escaping every non-alphanumeric character:

usersString.replace(/(?=\W)/g, '\\');

You lose a certain degree of readability when doing re.toString() but you win a great deal of simplicity (and security).

According to ECMA-262, on the one hand, regular expression "syntax characters" are always non-alphanumeric, such that the result is secure, and special escape sequences (\d, \w, \n) are always alphanumeric such that no false control escapes will be produced.

The located assembly's manifest definition does not match the assembly reference

Here's my method of fixing this issue.

  1. From the exception message, get the name of the "problem" library and the "expected" version number.

enter image description here

  1. Find all copies of that .dll in your solution, right-click on them, and check which version of the .dll it is.

enter image description here

Okay, so in this example, my .dll is definitely 2.0.5022.0 (so the Exception version number is wrong).

  1. Search for the version number which was shown in the Exception message in all of the .csproj files in your solution. Replace this version number with the actual number from the dll.

So, in this example, I would replace this...

<Reference Include="DocumentFormat.OpenXml, Version=2.5.5631.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />

... with this...

<Reference Include="DocumentFormat.OpenXml, Version=2.0.5022.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />

Job done !

Access denied for user 'root'@'localhost' with PHPMyAdmin

Edit your phpmyadmin file and if you have Password, insert that in front of Password in following code:

$cfg['Servers'][$i]['verbose'] = 'localhost';
$cfg['Servers'][$i]['host'] = 'localhost';
$cfg['Servers'][$i]['port'] = '3306';
$cfg['Servers'][$i]['socket'] = '';
$cfg['Servers'][$i]['connect_type'] = 'tcp';
$cfg['Servers'][$i]['extension'] = 'mysqli';
$cfg['Servers'][$i]['auth_type'] = 'config';
$cfg['Servers'][$i]['user'] = '**your-root-username**';
$cfg['Servers'][$i]['password'] = '**root-password**';
$cfg['Servers'][$i]['AllowNoPassword'] = true;

How to get selenium to wait for ajax response?

Here's a groovy version based on Morten Christiansen's answer.

void waitForAjaxCallsToComplete() {
            { return getJavaScriptFunction(driver, "return (window.jQuery || {active : false}).active") },
            "Ajax calls did not complete before timeout."

static void repeatUntil(Closure runUntilTrue, String errorMessage, int pollFrequencyMS = 250, int timeOutSeconds = 10) {
    def today = new Date()
    def end = today.time + timeOutSeconds
    def complete = false;

    while (today.time < end) {
        if (runUntilTrue()) {
            complete = true;

    if (!complete)
        throw new TimeoutException(errorMessage);

static String getJavaScriptFunction(WebDriver driver, String jsFunction) {
    def jsDriver = driver as JavascriptExecutor

How can I change IIS Express port for a site

To specify a port for a Web application project that uses IIS Express

  1. In Solution Explorer, right-click the name of the application and then select Properties. Click the Web tab.

  2. In the Servers section, under Use Local IIS Web server, in the Project URL box change the port number.

  3. To the right of the Project URL box, click Create Virtual Directory, and then click OK.

  4. In the File menu, click Save Selected Items.

  5. To verify the change, press CTRL+F5 to run the project. The new port number appears in the address bar of the browser.

From How to: Specify a Port for the Development Server ( backup here).

Merge 2 arrays of objects

const array1 = [{id:1,name:'ganza'},
{id:2,name:'respice dddd'},{id:4,name:'respice dddd'},{id:6,name:'respice dddd'},
{id:7,name:'respice dddd'}];
const array2 = [{id:1,name:'ganza respice'},{id:2,name:'respice'},{id:3,name:'mg'}];

 function mergeTwoArray(array1,array2){

        if(array2[i] &&[i].id){
          return array2[i];
            return item;

const result = mergeTwoArray(array1,array2);
//here is the result:  Array [Object { id: 1, name: "ganza respice" },
 Object { id: 2, name: "respice" }, Object { id: 4, name: "respice dddd" }, 
Object { id: 6, name: "respice dddd" }, Object { id: 7, name: "respice dddd" }]

How to change the output color of echo in Linux

I'm using this for color printing

#Color picker, usage: printf $BLD$CUR$RED$BBLU'Hello World!'$DEF     |
#       Text color        |       Background color         |         |
#-----------+-------------+--------------+-----------------+         |
# Base color|Lighter shade| Base color   | Lighter shade   |         |
#-----------+-------------+--------------+-----------------+         |
BLK='\e[30m'; blk='\e[90m'; BBLK='\e[40m'; bblk='\e[100m' #| Black   |
RED='\e[31m'; red='\e[91m'; BRED='\e[41m'; bred='\e[101m' #| Red     |
GRN='\e[32m'; grn='\e[92m'; BGRN='\e[42m'; bgrn='\e[102m' #| Green   |
YLW='\e[33m'; ylw='\e[93m'; BYLW='\e[43m'; bylw='\e[103m' #| Yellow  |
BLU='\e[34m'; blu='\e[94m'; BBLU='\e[44m'; bblu='\e[104m' #| Blue    |
MGN='\e[35m'; mgn='\e[95m'; BMGN='\e[45m'; bmgn='\e[105m' #| Magenta |
CYN='\e[36m'; cyn='\e[96m'; BCYN='\e[46m'; bcyn='\e[106m' #| Cyan    |
WHT='\e[37m'; wht='\e[97m'; BWHT='\e[47m'; bwht='\e[107m' #| White   |
#-------------------------{ Effects }----------------------+---------+
DEF='\e[0m'   #Default color and effects                             |
BLD='\e[1m'   #Bold\brighter                                         |
DIM='\e[2m'   #Dim\darker                                            |
CUR='\e[3m'   #Italic font                                           |
UND='\e[4m'   #Underline                                             |
INV='\e[7m'   #Inverted                                              |
COF='\e[?25l' #Cursor Off                                            |
CON='\e[?25h' #Cursor On                                             |
#------------------------{ Functions }-------------------------------+
# Text positioning, usage: XY 10 10 'Hello World!'                   |
XY () { printf "\e[$2;${1}H$3"; }                                   #|
# Print line, usage: line - 10 | line -= 20 | line 'Hello World!' 20 |
line () { printf -v _L %$2s; printf -- "${_L// /$1}"; }             #|
# Create sequence like {0..(X-1)}                                    |
que () { printf -v _N %$1s; _N=(${_N// / 1}); printf "${!_N[*]}"; } #|

All basic colors set as vars and also there are some usefull functions: XY, line and que. Source this script in one of yours and use all color vars and functions.

Trigger function when date is selected with jQuery UI datepicker

If the datepicker is in a row of a grid, try something like

editoptions : {
    dataInit : function (e) {
            onSelect : function (ev) {
                // here your code

submitting a form when a checkbox is checked

                if( $(this).is(":checked") )

Though it would probably be better to add classes to each of the checkboxes and do


so that you can choose which checkboxes submit the form instead of all of them doing it.

How to delay the .keyup() handler until the user stops typing?

Use the bindWithDelay jQuery plugin:

element.bindWithDelay(eventType, [ eventData ], handler(eventObject), timeout, throttle)

where to place CASE WHEN column IS NULL in this query

Thanks for all your help! @Svetoslav Tsolov had it very close, but I was still getting an error, until I figured out the closing parenthesis was in the wrong place. Here's the final query that works:

SELECT dbo.AdminID.CountryID, dbo.AdminID.CountryName, dbo.AdminID.RegionID, 
dbo.AdminID.[Region name], dbo.AdminID.DistrictID, dbo.AdminID.DistrictName,
dbo.AdminID.ADMIN3_ID, dbo.AdminID.ADMIN3,
FROM dbo.AdminID 

ON dbo.AdminID.DistrictID = dbo.EU_Admin2.DistrictID

ON dbo.AdminID.ADMIN3_ID = dbo.EU_Admin3.ADMIN3_ID

JavaScript data grid for millions of rows

Here are a couple of optimizations you can apply you speed up things. Just thinking out loud.

Since the number of rows can be in the millions, you will want a caching system just for the JSON data from the server. I can't imagine anybody wanting to download all X million items, but if they did, it would be a problem. This little test on Chrome for an array on 20M+ integers crashes on my machine constantly.

var data = [];
for(var i = 0; i < 20000000; i++) {

You could use LRU or some other caching algorithm and have an upper bound on how much data you're willing to cache.

For the table cells themselves, I think constructing/destroying DOM nodes can be expensive. Instead, you could just pre-define X number of cells, and whenever the user scrolls to a new position, inject the JSON data into these cells. The scrollbar would virtually have no direct relationship to how much space (height) is required to represent the entire dataset. You could arbitrarily set the table container's height, say 5000px, and map that to the total number of rows. For example, if the containers height is 5000px and there are a total of 10M rows, then the starting row ˜ ( * 10M where represents the scroll distance from the top of the container. Small demo here.

To detect when to request more data, ideally an object should act as a mediator that listens to scroll events. This object keeps track of how fast the user is scrolling, and when it looks like the user is slowing down or has completely stopped, makes a data request for the corresponding rows. Retrieving data in this fashion means your data is going to be fragmented, so the cache should be designed with that in mind.

Also the browser limits on maximum outgoing connections can play an important part. A user may scroll to a certain position which will fire an AJAX request, but before that finishes the user can scroll to some other portion. If the server is not responsive enough the requests would get queued up and the application will look unresponsive. You could use a request manager through which all requests are routed, and it can cancel pending requests to make space.

Open soft keyboard programmatically

Please follow the below code. I am sure your problem will be solved.

if (imm != null){

What is the difference between Html.Hidden and Html.HiddenFor

Most of the MVC helper methods have a XXXFor variant. They are intended to be used in conjunction with a concrete model class. The idea is to allow the helper to derive the appropriate "name" attribute for the form-input control based on the property you specify in the lambda. This means that you get to eliminate "magic strings" that you would otherwise have to employ to correlate the model properties with your views. For example:

Html.Hidden("Name", "Value")

Will result in:

<input id="Name" name="Name" type="hidden" value="Value">

In your controller, you might have an action like:

public ActionResult MyAction(MyModel model) 

And a model like:

public class MyModel 
    public string Name { get; set; }

The raw Html.Hidden we used above will get correlated to the Name property in the model. However, it's somewhat distasteful that the value "Name" for the property must be specified using a string ("Name"). If you rename the Name property on the Model, your code will break and the error will be somewhat difficult to figure out. On the other hand, if you use HiddenFor, you get protected from that:

Html.HiddenFor(x => x.Name, "Value");

Now, if you rename the Name property, you will get an explicit runtime error indicating that the property can't be found. In addition, you get other benefits of static analysis, such as getting a drop-down of the members after typing x..

ArrayList of String Arrays

private List<String[]> addresses = new ArrayList<String[]>();

this will work defenitely...

How to dismiss the dialog with click on outside of the dialog?


to close dialog on touch outside.

And if you don't want to close on touch outside, use the code below:


SSIS Connection Manager Not Storing SQL Password

The designed behavior in SSIS is to prevent storing passwords in a package, because it's bad practice/not safe to do so.

Instead, either use Windows auth, so you don't store secrets in packages or config files, or, if that's really impossible in your environment (maybe you have no Windows domain, for example) then you have to use a workaround as described in (Sam's correct, just read further in that article). The simplest answer is a config file to go with the package, but then you have to worry that the config file is stored securely so someone can't just read it and take the credentials.

How to run TypeScript files from command line?

To add to @Aamod answer above, If you want to use one command line to compile and run your code, you can use the following:


tsc main.ts | node main.js

Linux / macOS:

tsc main.ts && node main.js

Changing position of the Dialog on screen android

I used this code to show the dialog at the bottom of the screen:

Dialog dlg = <code to create custom dialog>;

Window window = dlg.getWindow();
WindowManager.LayoutParams wlp = window.getAttributes();

wlp.gravity = Gravity.BOTTOM;
wlp.flags &= ~WindowManager.LayoutParams.FLAG_DIM_BEHIND;

This code also prevents android from dimming the background of the dialog, if you need it. You should be able to change the gravity parameter to move the dialog about

private void showPictureialog() {
    final Dialog dialog = new Dialog(this,

    // Setting dialogview
    Window window = dialog.getWindow();

    window.setLayout(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

you can customize you dialog based on gravity and layout parameters change gravity and layout parameter on the basis of your requirenment

pow (x,y) in Java

^ is the bitwise exclusive OR (XOR) operator in Java (and many other languages). It is not used for exponentiation. For that, you must use Math.pow.

Copy file from source directory to binary directory using CMake

if you want to copy folder from currant directory to binary (build folder) folder


then the syntexe is :

file(COPY pathSource DESTINATION pathDistination)

How to prevent scrollbar from repositioning web page?

Wrap the content of your scrollable element into a div and apply padding-left: calc(100vw - 100%);.

    <div style="padding-left: calc(100vw - 100%);">
        Some Content that is higher than the user's screen

The trick is that 100vw represents 100% of the viewport including the scrollbar. If you subtract 100%, which is the available space without the scrollbar, you end up with the width of the scrollbar or 0 if it is not present. Creating a padding of that width on the left will simulate a second scrollbar, shifting centered content back to the right.

Please note that this will only work if the scrollable element uses the page's entire width, but this should be no problem most of the time because there are only few other cases where you have centered scrollable content.

How do I use dataReceived event of the SerialPort Port Object in C#?

First off I recommend you use the following constructor instead of the one you currently use:

new SerialPort("COM10", 115200, Parity.None, 8, StopBits.One);

Next, you really should remove this code:

// Wait 10 Seconds for data...
for (int i = 0; i < 1000; i++)
    Console.WriteLine(sp.Read(buf,0,bufSize)); //prints data directly to the Console

And instead just loop until the user presses a key or something, like so:

namespace serialPortCollection
{   class Program
        static void Main(string[] args)
            SerialPort sp = new SerialPort("COM10", 115200);
            sp.DataReceived += port_OnReceiveDatazz; // Add DataReceived Event Handler

            sp.WriteLine("$"); //Command to start Data Stream


            sp.WriteLine("!"); //Stop Data Stream Command

       // My Event Handler Method
        private static void port_OnReceiveDatazz(object sender, 
                                   SerialDataReceivedEventArgs e)
            SerialPort spL = (SerialPort) sender;
            byte[] buf = new byte[spL.BytesToRead];
            Console.WriteLine("DATA RECEIVED!");
            spL.Read(buf, 0, buf.Length);
            foreach (Byte b in buf)

Also, note the revisions to the data received event handler, it should actually print the buffer now.


I just ran the following code successfully on my machine (using a null modem cable between COM33 and COM34)

namespace TestApp
    class Program
        static void Main(string[] args)
            Thread writeThread = new Thread(new ThreadStart(WriteThread));
            SerialPort sp = new SerialPort("COM33", 115200, Parity.None, 8, StopBits.One);
            sp.DataReceived += port_OnReceiveDatazz; // Add DataReceived Event Handler

            sp.WriteLine("$"); //Command to start Data Stream



            sp.WriteLine("!"); //Stop Data Stream Command

        private static void port_OnReceiveDatazz(object sender, 
                                   SerialDataReceivedEventArgs e)
            SerialPort spL = (SerialPort) sender;
            byte[] buf = new byte[spL.BytesToRead];
            Console.WriteLine("DATA RECEIVED!");
            spL.Read(buf, 0, buf.Length);
            foreach (Byte b in buf)
                Console.Write(b.ToString() + " ");

        private static void WriteThread()
            SerialPort sp2 = new SerialPort("COM34", 115200, Parity.None, 8, StopBits.One);
            byte[] buf = new byte[100];
            for (byte i = 0; i < 100; i++)
                buf[i] = i;
            sp2.Write(buf, 0, buf.Length);


Given all of the traffic on this question recently. I'm beginning to suspect that either your serial port is not configured properly, or that the device is not responding.

I highly recommend you attempt to communicate with the device using some other means (I use hyperterminal frequently). You can then play around with all of these settings (bitrate, parity, data bits, stop bits, flow control) until you find the set that works. The documentation for the device should also specify these settings. Once I figured those out, I would make sure my .NET SerialPort is configured properly to use those settings.

Some tips on configuring the serial port:

Note that when I said you should use the following constructor, I meant that use that function, not necessarily those parameters! You should fill in the parameters for your device, the settings below are common, but may be different for your device.

new SerialPort("COM10", 115200, Parity.None, 8, StopBits.One);

It is also important that you setup the .NET SerialPort to use the same flow control as your device (as other people have stated earlier). You can find more info here:

How to get the filename without the extension from a path in Python?

But even when I import os, I am not able to call it path.basename. Is it possible to call it as directly as basename?

import os, and then use os.path.basename

importing os doesn't mean you can use without referring to os.

SQL- Ignore case while searching for a string

Use something like this -




Insert some string into given string at given index in Python

An important point that often bites new Python programmers but the other posters haven't made explicit is that strings in Python are immutable -- you can't ever modify them in place.

You need to retrain yourself when working with strings in Python so that instead of thinking, "How can I modify this string?" instead you're thinking "how can I create a new string that has some pieces from this one I've already gotten?"

How do I run a Python script on my web server?

Very simply, you can rename your Python script to "pythonscript.cgi". Post that in your cgi-bin directory, add the appropriate permissions and browse to it.

This is a great link you can start with.

Here's another good one.

Hope that helps.

EDIT (09/12/2015): The second link has long been removed. Replaced it with one that provides information referenced from the original.

How to run mvim (MacVim) from Terminal?

There should be a script named mvim in the root of the .bz2 file. Copy this somewhere into your $PATH ( /usr/local/bin would be good ) and you should be sorted.

Keep overflow div scrolled to bottom unless user scrolls up

I couldn't get the top two answers to work, and none of the other answers were helpful to me. So I paid three people $30 from Reddit r/forhire and Upwork and got some really good answers. This answer should save you $90.

Justin Hundley / The Site Bros' solution


<div id="chatscreen">
  <div id="inner">


#chatscreen {
  width: 300px;
  overflow-y: scroll;


    var scrolled = false;
  var lastScroll = 0;
  var count = 0;
    $("#chatscreen").on("scroll", function() {
    var nextScroll = $(this).scrollTop();

    if (nextScroll <= lastScroll) {
        scrolled = true;
    lastScroll = nextScroll;
    console.log(nextScroll, $("#inner").height())
    if ((nextScroll + 100) == $("#inner").height()) {
        scrolled = false;
  function updateScroll(){
          var element = document.getElementById("chatscreen");
          var inner = document.getElementById("inner");
          element.scrollTop = inner.scrollHeight;

  // Now let's load our messages
  function load_messages(){
      $( "#inner" ).append( "Test" + count + "<br/>" );
      count = count + 1;


Preview the site bros' solution


Lermex / Sviatoslav Chumakov's solution


<div id="chatscreen">



#chatscreen {
  height: 300px;
  border: 1px solid purple;
  overflow: scroll;


var isScrolledToBottom = false;
// Now let's load our messages
function load_messages(){
    $( "#chatscreen" ).append( "<br>Test" );

var out = document.getElementById("chatscreen");
var c = 0;

$("#chatscreen").on('scroll', function(){
    isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 10;

function updateScr() {
        // allow 1px inaccuracy by adding 1
    //console.log(out.scrollHeight - out.clientHeight,  out.scrollTop + 1);
    var newElement = document.createElement("div");

    newElement.innerHTML = c++;

    // scroll to bottom if isScrolledToBotto
    if(isScrolledToBottom) {out.scrollTop = out.scrollHeight - out.clientHeight; }

var add = setInterval(updateScr, 1000);

setInterval(load_messages,300); // change to 300 to show the latest message you sent after pressing enter // comment this line and it works, uncomment and it fails
                                // leaving it on 1000 shows the second to last message

Preview Sviatoslav's solution


Igor Rusinov's Solution


<div id="chatscreen"></div>


#chatscreen {
  height: 100px;
  overflow: scroll;
  border: 1px solid #000;



// Now let's load our messages
function load_messages(){
    $( "#chatscreen" ).append( "<br>Test" );

var out = document.getElementById("chatscreen");
var c = 0;
var add = setInterval(function() {
    // allow 1px inaccuracy by adding 1
    var isScrolledToBottom = out.scrollHeight - out.clientHeight <= out.scrollTop + 1;

    // scroll to bottom if isScrolledToBotto
    if(isScrolledToBottom) {out.scrollTop = out.scrollHeight - out.clientHeight; }
}, 1000);

Preview Igor's solution


How to lowercase a pandas dataframe string column if it has missing values?

Use apply function,

Xlower = df['x'].apply(lambda x: x.upper()).head(10) 

How to completely remove Python from a Windows machine?

Uninstall the python program using the windows GUI. Delete the containing folder e.g if it was stored in C:\python36\ make sure to delete that folder

Reading Space separated input in python

For python 3 it would be like this n,m,p=map(int,input().split())

How to post a file from a form with Axios

This works for me, I hope helps to someone.

var frm = $('#frm');
let formData = new FormData(frm[0]);'your-url', formData)
    .then(res => {
    }).catch(err => {

How to install pip with Python 3?

if you're using python 3.4+

just type:

python3 -m pip

Run a command over SSH with JSch

Note that Charity Leschinski's answer may have a bit of an issue when there is some delay in the response. eg:
lparstat 1 5 returns one response line and works,
lparstat 5 1 should return 5 lines, but only returns the first

I've put the command output while inside another ... I'm sure there is a better way, I had to do this as a quick fix

        while (commandOutput.available() > 0) {
            while (readByte != 0xffffffff) {
                outputBuffer.append((char) readByte);
                readByte =;
            try {Thread.sleep(1000);} catch (Exception ee) {}

How do I wait for an asynchronously dispatched block to finish?

In addition to the semaphore technique covered exhaustively in other answers, we can now use XCTest in Xcode 6 to perform asynchronous tests via XCTestExpectation. This eliminates the need for semaphores when testing asynchronous code. For example:

- (void)testDataTask
    XCTestExpectation *expectation = [self expectationWithDescription:@"asynchronous request"];

    NSURL *url = [NSURL URLWithString:@""];
    NSURLSessionTask *task = [self.session dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        XCTAssertNil(error, @"dataTaskWithURL error %@", error);

        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
            NSInteger statusCode = [(NSHTTPURLResponse *) response statusCode];
            XCTAssertEqual(statusCode, 200, @"status code was not 200; was %d", statusCode);

        XCTAssert(data, @"data nil");

        // do additional tests on the contents of the `data` object here, if you want

        // when all done, Fulfill the expectation

        [expectation fulfill];
    [task resume];

    [self waitForExpectationsWithTimeout:10.0 handler:nil];

For the sake of future readers, while the dispatch semaphore technique is a wonderful technique when absolutely needed, I must confess that I see too many new developers, unfamiliar with good asynchronous programming patterns, gravitate too quickly to semaphores as a general mechanism for making asynchronous routines behave synchronously. Worse I've seen many of them use this semaphore technique from the main queue (and we should never block the main queue in production apps).

I know this isn't the case here (when this question was posted, there wasn't a nice tool like XCTestExpectation; also, in these testing suites, we must ensure the test does not finish until the asynchronous call is done). This is one of those rare situations where the semaphore technique for blocking the main thread might be necessary.

So with my apologies to the author of this original question, for whom the semaphore technique is sound, I write this warning to all of those new developers who see this semaphore technique and consider applying it in their code as a general approach for dealing with asynchronous methods: Be forewarned that nine times out of ten, the semaphore technique is not the best approach when encounting asynchronous operations. Instead, familiarize yourself with completion block/closure patterns, as well as delegate-protocol patterns and notifications. These are often much better ways of dealing with asynchronous tasks, rather than using semaphores to make them behave synchronously. Usually there are good reasons that asynchronous tasks were designed to behave asynchronously, so use the right asynchronous pattern rather than trying to make them behave synchronously.

How to retrieve the last autoincremented ID from a SQLite table?

One other option is to look at the system table sqlite_sequence. Your sqlite database will have that table automatically if you created any table with autoincrement primary key. This table is for sqlite to keep track of the autoincrement field so that it won't repeat the primary key even after you delete some rows or after some insert failed (read more about this here

So with this table there is the added benefit that you can find out your newly inserted item's primary key even after you inserted something else (in other tables, of course!). After making sure that your insert is successful (otherwise you will get a false number), you simply need to do:

select seq from sqlite_sequence where name="table_name"

How do I set a fixed background image for a PHP file?

It's not a good coding to put PHP code into CSS


that's it


Am I missing something?

Doesn't this hypothetical code

while(rowIndex >= dataColLinker.size()) {
} else {
    dataColLinker.set(rowIndex, value);

mean the same thing as this?

while(rowIndex >= dataColLinker.size()) {
dataColLinker.set(rowIndex, value);

or this?

if (rowIndex >= dataColLinker.size()) {
    do {
    } while(rowIndex >= dataColLinker.size());
} else {
    dataColLinker.set(rowIndex, value);

(The latter makes more sense ... I guess). Either way, it is obvious that you can rewrite the loop so that the "else test" is not repeated inside the loop ... as I have just done.

FWIW, this is most likely a case of premature optimization. That is, you are probably wasting your time optimizing code that doesn't need to be optimized:

  • For all you know, the JIT compiler's optimizer may have already moved the code around so that the "else" part is no longer in the loop.

  • Even if it hasn't, the chances are that the particular thing you are trying to optimize is not a significant bottleneck ... even if it might be executed 600,000 times.

My advice is to forget this problem for now. Get the program working. When it is working, decide if it runs fast enough. If it doesn't then profile it, and use the profiler output to decide where it is worth spending your time optimizing.

how to access the command line for xampp on windows

Xampp has the php application under: C:\xampp\php file directory ... if you input C:\xampp\php\php in CMD it should enter the php application.

How to print Boolean flag in NSLog?

In Swift, you can simply print a boolean value and it will be displayed as true or false.

let flag = true
print(flag) //true

Table is marked as crashed and should be repaired

Here is where the repair button is:

alt text

Curl and PHP - how can I pass a json through curl by PUT,POST,GET

set one more property curl_setopt($ch, CURLOPT_SSL_VERIFYPEER , false);

Changing git commit message after push (given that no one pulled from remote)

additional information for same problem if you are using bitbucket pipeline

edit your message

git commit --amend

push to the sever

git push --force <repository> <branch>

then add --force to your push command on the pipeline

git ftp push --force

This will delete your previous commit(s) and push your current one.

remove the --force after first push

i tried it on bitbucket pipeline and its working fine

open the file upload dialogue box onclick the image

<!-- File input (hidden) -->
<input type="file" id="file1" style="display:none"/>    

<!-- Trigger button -->
<a href="javascript:void(0)" onClick="openSelect('#file1')">

<script type="text/javascript">                            
function openSelect(file)

Modify tick label text

It's been a while since this question was asked. As of today (matplotlib 2.2.2) and after some reading and trials, I think the best/proper way is the following:

Matplotlib has a module named ticker that "contains classes to support completely configurable tick locating and formatting". To modify a specific tick from the plot, the following works for me:

import matplotlib.pyplot as plt
import matplotlib.ticker as mticker
import numpy as np 

def update_ticks(x, pos):
    if x == 0:
        return 'Mean'
    elif pos == 6:
        return 'pos is 6'
        return x

data = np.random.normal(0, 1, 1000)
fig, ax = plt.subplots()
ax.hist(data, bins=25, edgecolor='black')

Histogram with random values from a normal distribution

Caveat! x is the value of the tick and pos is its relative position in order in the axis. Notice that pos takes values starting in 1, not in 0 as usual when indexing.

In my case, I was trying to format the y-axis of a histogram with percentage values. mticker has another class named PercentFormatter that can do this easily without the need to define a separate function as before:

import matplotlib.pyplot as plt
import matplotlib.ticker as mticker
import numpy as np 

data = np.random.normal(0, 1, 1000)
fig, ax = plt.subplots()
weights = np.ones_like(data) / len(data)
ax.hist(data, bins=25, weights=weights, edgecolor='black')
ax.yaxis.set_major_formatter(mticker.PercentFormatter(xmax=1.0, decimals=1))

Histogram with random values from a normal distribution

In this case xmax is the data value that corresponds to 100%. Percentages are computed as x / xmax * 100, that's why we fix xmax=1.0. Also, decimals is the number of decimal places to place after the point.

GROUP BY and COUNT in PostgreSQL

I think you just need COUNT(DISTINCT post_id) FROM votes.

See "4.2.7. Aggregate Expressions" section in

EDIT: Corrected my careless mistake per Erwin's comment.

OS X Framework Library not loaded: 'Image not found'

For me this was the solution, after many hours of searching!!

For some reason, well into the development of a Swift 2.3 custom Framework, Xcode 8 had removed the DYLIB_INSTALL_NAME_BASE setting from the project.pbxproj file. A little walk into the Build Settings / Dynamic Library Install Name Base setting back to @rpath fixed it.


Load content of a div on another page

You just need to add a jquery selector after the url.


Example straight from the API:

$('#result').load('ajax/test.html #container');

So what that does is it loads the #container element from the specified url.

Could not obtain information about Windows NT group user

I had to connect to VPN for the publish script to successfully deploy to the DB.

Split a string by another string in C#

Regex.Split(string, "xx")

is the way I do it usually.

Of course you'll need:

using System.Text.RegularExpressions;

or :

System.Text.RegularExpressions.Regex.Split(string, "xx")

but then again I need that library all the time.

How to register multiple implementations of the same interface in Asp.Net Core?

I did a simple workaround using Func when I found myself in this situation.

Firstly declare a shared delegate:

public delegate IService ServiceResolver(string key);

Then in your Startup.cs, setup the multiple concrete registrations and a manual mapping of those types:


services.AddTransient<ServiceResolver>(serviceProvider => key =>
    switch (key)
        case "A":
            return serviceProvider.GetService<ServiceA>();
        case "B":
            return serviceProvider.GetService<ServiceB>();
        case "C":
            return serviceProvider.GetService<ServiceC>();
            throw new KeyNotFoundException(); // or maybe return null, up to you

And use it from any class registered with DI:

public class Consumer
    private readonly IService _aService;

    public Consumer(ServiceResolver serviceAccessor)
        _aService = serviceAccessor("A");

    public void UseServiceA()

Keep in mind that in this example the key for resolution is a string, for the sake of simplicity and because OP was asking for this case in particular.

But you could use any custom resolution type as key, as you do not usually want a huge n-case switch rotting your code. Depends on how your app scales.

Hide html horizontal but not vertical scrollbar

You can use css like this:

overflow-y: scroll;
overflow-x: hidden;

How to set width of a div in percent in JavaScript?


    $(document).ready(function() { 
        rules: { 
          name: "required", //simple rule, converted to {required:true} 
          email: { //compound rule 
          required: true, 
          email: true 
        url: { 
          url: true 
        comment: { 
          required: true 
        messages: { 
          comment: "Please enter a comment." 

    var ok=confirm('Click "OK" to go to yahoo, "CANCEL" to go to hotmail')
    if (ok)

    function changeWidth(){
    var e1 = document.getElementById("e1"); = 400;


  <style type="text/css"> 
    * { font-family: Verdana; font-size: 11px; line-height: 14px; } 
    .submit { margin-left: 125px; margin-top: 10px;} 
    .label { display: block; float: left; width: 120px; text-align: right; margin-right: 5px; } 
    .form-row { padding: 5px 0; clear: both; width: 700px; } 
    .label.error { width: 250px; display: block; float: left; color: red; padding-left: 10px; } 
    .input[type=text], textarea { width: 250px; float: left; } 
    .textarea { height: 50px; } 


    <form id="form1" method="post" action=""> 
      <div class="form-row"><span class="label">Name *</span><input type="text" name="name" /></div> 
      <div class="form-row"><span class="label">E-Mail *</span><input type="text" name="email" /></div> 
      <div class="form-row"><span class="label">URL </span><input type="text" name="url" /></div> 
      <div class="form-row"><span class="label">Your comment *</span><textarea name="comment" ></textarea></div> 
      <div class="form-row"><input class="submit" type="submit" value="Submit"></div> 
      <input type="button" value="change width" onclick="changeWidth()"/>
      <div id="e1" style="width:20px;height:20px; background-color:#096"></div>


What do I need to do to get Internet Explorer 8 to accept a self signed certificate?

I had the same issue while working with web services. Here Microsoft has a (long) walk-thru showing you how to install stuff on the client to basically say that your self-signed cert is ok. In the end, I just spent the $30 and bought a full certificate from

P.S. I know that you can code around the error message but we didn't want to do that for testing reasons.

When is layoutSubviews called?

A rather obscure, yet potentially important case when layoutSubviews never gets called is:

import UIKit

class View: UIView {

    override class var layerClass: AnyClass { return Layer.self }

    class Layer: CALayer {
        override func layoutSublayers() {
            // if we don't call super.layoutSublayers()...
            print(type(of: self), #function)

    override func layoutSubviews() {
        // ... this method never gets called by the OS!
        print(type(of: self), #function)

let view = View(frame: CGRect(x: 0, y: 0, width: 100, height: 100))

Adding null values to arraylist

Yes, you can always use null instead of an object. Just be careful because some methods might throw error.

It would be 1.

also nulls would be factored in in the for loop, but you could use

 for(Item i : itemList) {
        if (i!= null) {
               //code here

ASP.NET MVC 3 Razor: Include JavaScript file in the head tag

You can use Named Sections.


    <script type="text/javascript" src="@Url.Content("/Scripts/jquery-1.6.2.min.js")"></script>
    @RenderSection("JavaScript", required: false)


@section JavaScript
   <script type="text/javascript" src="@Url.Content("/Scripts/SomeScript.js")"></script>
   <script type="text/javascript" src="@Url.Content("/Scripts/AnotherScript.js")"></script>

How to secure database passwords in PHP?

Put the database password in a file, make it read-only to the user serving the files.

Unless you have some means of only allowing the php server process to access the database, this is pretty much all you can do.

How to copy text programmatically in my Android app?

Use ClipboardManager#setPrimaryClip method:

import android.content.ClipboardManager;

// ...

ClipboardManager clipboard = (ClipboardManager) getSystemService(CLIPBOARD_SERVICE); 
ClipData clip = ClipData.newPlainText("label", "Text to copy");

ClipboardManager API reference

Where Sticky Notes are saved in Windows 10 1607

Use this document to transfer Sticky Notes data file StickyNotes.snt to the new format



  • Close Sticky Notes
  • Create a new folder named Legacy
  • Under the Legacy folder, copy your existing StickyNotes.snt, and rename it to ThresholdNotes.snt
  • Start the Sticky Notes app. It reads the legacy .snt file and transfers the content to the database file automatically.


just backup following file.


How to connect to mysql with laravel?

I spent a lot of time trying to figure this one out. Finally, I tried shutting down my development server and booting it up again. Frustratingly, this worked for me. I came to the conclusion, that after editing the .env file in Laravel 5, you have to exit the server, and run php artisan serve again.

Filtering collections in C#

You can use the FindAll method of the List, providing a delegate to filter on. Though, I agree with @IainMH that it's not worth worrying yourself too much unless it's a huge list.

How to check if an element is in an array


If you are not using object then you can user this code for contains.

let elements = [ 10, 20, 30, 40, 50]

if elements.contains(50) {



If you are using NSObject Class in swift. This variables is according to my requirement. you can modify for your requirement.

var cliectScreenList = [ATModelLeadInfo]()
var cliectScreenSelectedObject: ATModelLeadInfo!

This is for a same data type.

{ $0.user_id == cliectScreenSelectedObject.user_id }

If you want to AnyObject type.

{ "\($0.user_id)" == "\(cliectScreenSelectedObject.user_id)" }

Full condition

if cliectScreenSelected.contains( { $0.user_id == cliectScreenSelectedObject.user_id } ) == false {


    print("Object Added")

} else {

    print("Object already exists")



You did the right thing by checking from query plans. But I have 100% confidence in version 2. It is faster when the number off records are on the very high side.

My database has around 1,000,000 records and this is exactly the scenario where the query plan shows the difference between both the queries. Further, instead of using a where clause, if you use it in the join itself, it makes the query faster :
SELECT p.Name, s.OrderQty
FROM Product p
INNER JOIN (SELECT ProductID, OrderQty FROM SalesOrderDetail) s on p.ProductID = s.ProductID WHERE p.isactive = 1

The better version of this query is :

SELECT p.Name, s.OrderQty
FROM Product p
INNER JOIN (SELECT ProductID, OrderQty FROM SalesOrderDetail) s on p.ProductID = s.ProductID AND p.isactive = 1

(Assuming isactive is a field in product table which represents the active/inactive products).

Configure hibernate (using JPA) to store Y/N for type Boolean instead of 0/1

To even do better boolean mapping to Y/N, add to your hibernate configuration:

<!-- when using type="yes_no" for booleans, the line below allow booleans in HQL expressions: -->
<property name="hibernate.query.substitutions">true 'Y', false 'N'</property>

Now you can use booleans in HQL, for example:

"FROM " + SomeDomainClass.class.getName() + " somedomainclass " +
"WHERE somedomainclass.someboolean = false"

HTML - Display image after selecting filename

You can achieve this with the following code:

$("input").change(function(e) {

    for (var i = 0; i < e.originalEvent.srcElement.files.length; i++) {

        var file = e.originalEvent.srcElement.files[i];

        var img = document.createElement("img");
        var reader = new FileReader();
        reader.onloadend = function() {
             img.src = reader.result;


How to Split Image Into Multiple Pieces in Python

I tried the solutions above, but sometimes you just gotta do it yourself. Might be off by a pixel in some cases but works fine in general.

import matplotlib.pyplot as plt
import numpy as np
def image_to_tiles(im, number_of_tiles = 4, plot=False):
    Function that splits SINGLE channel images into tiles
    :param im: image: single channel image (NxN matrix)
    :param number_of_tiles: squared number
    :param plot:
    :return tiles:
    n_slices = np.sqrt(number_of_tiles)
    assert int(n_slices + 0.5) ** 2 == number_of_tiles, "Number of tiles is not a perfect square"

    n_slices = n_slices.astype(
    [w, h] = cropped_npy.shape

    r = np.linspace(0, w, n_slices+1)
    r_tuples = [([i]),[i+1])) for i in range(0, len(r)-1)]
    q = np.linspace(0, h, n_slices+1)
    q_tuples = [([i]),[i+1])) for i in range(0, len(q)-1)]

    tiles = []
    for row in range(n_slices):
        for column in range(n_slices):
            [x1, y1, x2, y2] = *r_tuples[row], *q_tuples[column] 
            tiles.append(im[x1:y1, x2:y2])

    if plot:
        fig, axes = plt.subplots(n_slices, n_slices, figsize=(10,10))
        c = 0
        for row in range(n_slices):
            for column in range(n_slices):

    return tiles

Hope it helps.

Split string to equal length substrings in Java

Here is my version based on RegEx and Java 8 streams. It's worth to mention that Matcher.results() method is available since Java 9.

Test included.

public static List<String> splitString(String input, int splitSize) {
    Matcher matcher = Pattern.compile("(?:(.{" + splitSize + "}))+?").matcher(input);
    return matcher.results().map(MatchResult::group).collect(Collectors.toList());

public void shouldSplitStringToEqualLengthParts() {
    String anyValidString = "Split me equally!";
    String[] expectedTokens2 = {"Sp", "li", "t ", "me", " e", "qu", "al", "ly"};
    String[] expectedTokens3 = {"Spl", "it ", "me ", "equ", "all"};

    Assert.assertArrayEquals(expectedTokens2, splitString(anyValidString, 2).toArray());
    Assert.assertArrayEquals(expectedTokens3, splitString(anyValidString, 3).toArray());

Split function in oracle to comma separated values with automatic sequence

Use this 'Split' function:

CREATE OR REPLACE FUNCTION Split (p_str varchar2) return sys_refcursor is
v_res sys_refcursor;

  open v_res for 
  select substr(STR, instr(STR, ',', 1, lvl) + 1, instr(STR, ',', 1, lvl + 1) - instr(STR, ',', 1, lvl) - 1) name 
    ( select ',' || STR || ',' as STR from TAB ),
    ( select level as lvl from dual connect by level <= 100 )
    where lvl <= length(STR) - length(replace(STR, ',')) - 1;

     return v_res;

You can't use this function in select statement like you described in question, but I hope you will find it still useful.

EDIT: Here are steps you need to do. 1. Create Object: create or replace type empy_type as object(value varchar2(512)) 2. Create Type: create or replace type t_empty_type as table of empy_type 3. Create Function:

CREATE OR REPLACE FUNCTION Split (p_str varchar2) return sms.t_empty_type is
v_emptype t_empty_type := t_empty_type();
v_cnt     number := 0;
v_res sys_refcursor;
v_value nvarchar2(128);
  open v_res for
  select substr(STR, instr(STR, ',', 1, lvl) + 1, instr(STR, ',', 1, lvl +     1) - instr(STR, ',', 1, lvl) - 1) name
    ( select ',' || STR || ',' as STR from TAB ),
    ( select level as lvl from dual connect by level <= 100 )
    where lvl <= length(STR) - length(replace(STR, ',')) - 1;

     fetch v_res into v_value;
      exit when v_res%NOTFOUND;
      v_cnt := v_cnt + 1;
     v_emptype(v_cnt) := empty_type(v_value);
    end loop;
    close v_res;

    return v_emptype;

Then just call like this:

SELECT * FROM (TABLE(split('a,b,c,d,g'))) 

Possible to restore a backup of SQL Server 2014 on SQL Server 2012?

Sure it's possible... use Export Wizard in source option use SQL SERVER NATIVE CLIENT 11, later your source server ex.\SQLEXPRESS next step select your new destination server ex.\SQL2014

Just be sure to be using correct instance and connect each other

Just pay attention in Stored procs must be recompiled

node.js: cannot find module 'request'

if some module you cant find, try with Static URI, for example:

var Mustache = require("/media/fabio/Datos/Express/2_required_a_module/node_modules/mustache/mustache.js");

This example, run on Ubuntu Gnome 16.04 of 64 bits, node -v: v4.2.6, npm: 3.5.2 Refer to: Blog of Ben Nadel

How to getText on an input in protractor

You have to use Promise to print or store values of element.

 var ExpectedValue:string ="";
          element("xyz")).getAttribute("value").then(function (Text) {

                        expect(Text.trim()).toEqual("ExpectedValue", "Wrong page navigated");//Assertion
        console.log("Text");//Print here in Console


How to SSH to a VirtualBox guest externally through a host?

On secure networks setting your network to bridge might not work. Administrators could only allow one mac address per port or even worse block the port should the switches detect multiple macs on one port.

The best solution in my opinion is to set up additional network interfaces to handle additional services you would like to run on your machines. So I have a bridge interface to allow for bridging when I take my laptop home and can SSH into it from other devices on my network as well as a host only adapter when I would like to SSH into my VM from my laptop when I am connected to the eduroam wifi network on campus.

Kotlin Android start new Activity

Well, I found these 2 ways to be the simplest of all outcomes:

Way #1:

accoun_btn.setOnClickListener {

Way#2: (In a generic way)

    accoun_btn.setOnClickListener {

    private inline fun <reified T> startActivity(context: Context) {


How to change checkbox's border style in CSS?

put it in a div and add border to the div

How to open a page in a new window or tab from code-behind

This code works for me:

Dim script As String = "<script type=""text/javascript"">'" & URL.ToString & "');</script>"
ClientScript.RegisterStartupScript(Me.GetType, "openWindow", script)

How do you sign a Certificate Signing Request with your Certification Authority?

In addition to answer of @jww, I would like to say that the configuration in openssl-ca.cnf,

default_days     = 1000         # How long to certify for

defines the default number of days the certificate signed by this root-ca will be valid. To set the validity of root-ca itself you should use '-days n' option in:

openssl req -x509 -days 3000 -config openssl-ca.cnf -newkey rsa:4096 -sha256 -nodes -out cacert.pem -outform PEM

Failing to do so, your root-ca will be valid for only the default one month and any certificate signed by this root CA will also have validity of one month.

Explanation of "ClassCastException" in Java

You are trying to treat an object as an instance of a class that it is not. It's roughly analogous to trying to press the damper pedal on a guitar (pianos have damper pedals, guitars don't).

Java Class.cast() vs. cast operator

Personally, I've used this before to build a JSON to POJO converter. In the case that the JSONObject processed with the function contains an array or nested JSONObjects (implying that the data here isn't of a primitive type or String), I attempt to invoke the setter method using class.cast() in this fashion:

public static Object convertResponse(Class<?> clazz, JSONObject readResultObject) {
    for(Method m : clazz.getMethods()) {
        if(!m.isAnnotationPresent(convertResultIgnore.class) && 
            m.getName().toLowerCase().startsWith("set")) {
        m.invoke(returnObject,  m.getParameters()[0].getClass().cast(convertResponse(m.getParameters()[0].getType(), readResultObject.getJSONObject(key))));

Not sure if this is extremely helpful, but as said here before, reflection is one of the very few legitimate use case of class.cast() I can think of, at least you have another example now.

Can I load a UIImage from a URL?

And the swift version :

   let url = NSURL.URLWithString("");
    var err: NSError?
    var imageData :NSData = NSData.dataWithContentsOfURL(url,options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &err)
    var bgImage = UIImage(data:imageData)

invalid use of non-static member function

You must make Foo::comparator static or wrap it in a std::mem_fun class object. This is because lower_bounds() expects the comparer to be a class of object that has a call operator, like a function pointer or a functor object. Also, if you are using C++11 or later, you can also do as dwcanillas suggests and use a lambda function. C++11 also has std::bind too.


// Binding:
std::lower_bounds(first, last, value, std::bind(&Foo::comparitor, this, _1, _2));
// Lambda:
std::lower_bounds(first, last, value, [](const Bar & first, const Bar & second) { return ...; });

Are there any disadvantages to always using nvarchar(MAX)?

This will cause a performance problem, although it may never cause any actual issues if your database is small. Each record will take up more space on the hard drive and the database will need to read more sectors of the disk if you're searching through a lot of records at once. For example, a small record could fit 50 to a sector and a large record could fit 5. You'd need to read 10 times as much data from the disk using the large record.

Identifier is undefined

You may also be missing using namespace std;

How to pass variable number of arguments to a PHP function

This is now possible with PHP 5.6.x, using the ... operator (also known as splat operator in some languages):


function addDateIntervalsToDateTime( DateTime $dt, DateInterval ...$intervals )
    foreach ( $intervals as $interval ) {
        $dt->add( $interval );
    return $dt;

addDateIntervaslToDateTime( new DateTime, new DateInterval( 'P1D' ), 
        new DateInterval( 'P4D' ), new DateInterval( 'P10D' ) );

Convert INT to FLOAT in SQL

In oracle db there is a trick for casting int to float (I suppose, it should also work in mysql):

select myintfield + 0.0 as myfloatfield from mytable

While @Heximal's answer works, I don't personally recommend it.

This is because it uses implicit casting. Although you didn't type CAST, either the SUM() or the 0.0 need to be cast to be the same data-types, before the + can happen. In this case the order of precedence is in your favour, and you get a float on both sides, and a float as a result of the +. But SUM(aFloatField) + 0 does not yield an INT, because the 0 is being implicitly cast to a FLOAT.

I find that in most programming cases, it is much preferable to be explicit. Don't leave things to chance, confusion, or interpretation.

If you want to be explicit, I would use the following.

CAST(SUM( AS FLOAT) * cp.price
-- using MySQL CAST FLOAT  requires 8.0

I won't discuss whether NUMERIC or FLOAT *(fixed point, instead of floating point)* is more appropriate, when it comes to rounding errors, etc. I'll just let you google that if you need to, but FLOAT is so massively misused that there is a lot to read about the subject already out there.

You can try the following to see what happens...

CAST(SUM( AS NUMERIC(10,4)) * CAST(cp.price AS NUMERIC(10,4))

Importing CSV File to Google Maps

The easiest way to do this is generate a KML file (see for a possible solution). You can then open that up in Google Maps by storing it online and linking to it from Google Maps as described at

EDIT: may let you do it without coding.

How to clone an InputStream?

You can't clone it, and how you are going to solve your problem depends on what the source of the data is.

One solution is to read all data from the InputStream into a byte array, and then create a ByteArrayInputStream around that byte array, and pass that input stream into your method.

Edit 1: That is, if the other method also needs to read the same data. I.e you want to "reset" the stream.

How to add and remove item from array in components in Vue 2

There are few mistakes you are doing:

  1. You need to add proper object in the array in addRow method
  2. You can use splice method to remove an element from an array at particular index.
  3. You need to pass the current row as prop to my-item component, where this can be modified.

You can see working code here.

   this.rows.push({description: '', unitprice: '' , code: ''}); // what to push unto the rows array?
   this. itemList.splice(index, 1)

Styling input buttons for iPad and iPhone

You may be looking for

-webkit-appearance: none;

Printing Python version in output


python --version 


python -V

This will return a current python version in terminal.

Decimal or numeric values in regular expression validation

A simple regex to match a numeric input and optional 2 digits decimal.


You can modify the {0,2} to match your decimal preference {min, max}

Snippet for validation:

const source = document.getElementById('source');
source.addEventListener('input', allowOnlyNumberAndDecimals);

function allowOnlyNumberAndDecimals(e) {
  let str =
  const regExp = /^\d*(\.)?(\d{0,2})?$/

  status = regExp.test(str) ? 'valid' : 'invalid'

  console.log(status + ' : ' + source.value)
<input type="text" id="source" />

PPT to PNG with transparent background

I just tried to make a transparent image with powerpoint after failing miserably with other online systems. I was successful. Amazing.

First I used word art to give me typefaces which convert well to PNG or JPEG. The ordinary text in powerpoint does not convert well. It gets fuzzy. Anyway, I typed in my words in white (my choice of colour as i wanted it against a navy blue background), arranged it how i wanted, then right clicked and selected format shape to remove lines, then shadow to set the transparency.

I took the transparency to 100%. It came out fine. i then right clicked to save as png. Opened the image with MS Picture manager and resized the image to my suiting. It did not come out with the powerpoint white background at all. Once resized, i dropped the image against my navy blue background and it was like magic.

How to connect to Mysql Server inside VirtualBox Vagrant?

Log in to your box with ssh [email protected] -p 2222 (password vagrant)

Then: sudo nano /etc/mysql/my.cnf and comment out the following lines with #


save it & exit

then: sudo service mysql restart

Then you can connect through SSH to your MySQL server.

How to convert comma-delimited string to list in Python?

You can use this function to convert comma-delimited single character strings to list-

def stringtolist(x):
    for i in range(0,len(x),2):
    return mylist

How to parse a JSON Input stream

All the current answers assume that it is okay to pull the entire JSON into memory where the advantage of an InputStream is that you can read the input little by little. If you would like to avoid reading the entire Json file at once then I would suggest using the Jackson library (which is my personal favorite but I'm sure others like Gson have similar functions).

With Jackson you can use a JsonParser to read one section at a time. Below is an example of code I wrote that wraps the reading of an Array of JsonObjects in an Iterator. If you just want to see an example of Jackson, look at the initJsonParser, initFirstElement, and initNextObject methods.

public class JsonObjectIterator implements Iterator<Map<String, Object>>, Closeable {
    private static final Logger LOG = LoggerFactory.getLogger(JsonObjectIterator.class);

    private final InputStream inputStream;
    private JsonParser jsonParser;
    private boolean isInitialized;

    private Map<String, Object> nextObject;

    public JsonObjectIterator(final InputStream inputStream) {
        this.inputStream = inputStream;
        this.isInitialized = false;
        this.nextObject = null;

    private void init() {
        this.isInitialized = true;

    private void initJsonParser() {
        final ObjectMapper objectMapper = new ObjectMapper();
        final JsonFactory jsonFactory = objectMapper.getFactory();

        try {
            this.jsonParser = jsonFactory.createParser(inputStream);
        } catch (final IOException e) {
            LOG.error("There was a problem setting up the JsonParser: " + e.getMessage(), e);
            throw new RuntimeException("There was a problem setting up the JsonParser: " + e.getMessage(), e);

    private void initFirstElement() {
        try {
            // Check that the first element is the start of an array
            final JsonToken arrayStartToken = this.jsonParser.nextToken();
            if (arrayStartToken != JsonToken.START_ARRAY) {
                throw new IllegalStateException("The first element of the Json structure was expected to be a start array token, but it was: " + arrayStartToken);

            // Initialize the first object
        } catch (final Exception e) {
            LOG.error("There was a problem initializing the first element of the Json Structure: " + e.getMessage(), e);
            throw new RuntimeException("There was a problem initializing the first element of the Json Structure: " + e.getMessage(), e);


    private void initNextObject() {
        try {
            final JsonToken nextToken = this.jsonParser.nextToken();

            // Check for the end of the array which will mean we're done
            if (nextToken == JsonToken.END_ARRAY) {
                this.nextObject = null;

            // Make sure the next token is the start of an object
            if (nextToken != JsonToken.START_OBJECT) {
                throw new IllegalStateException("The next token of Json structure was expected to be a start object token, but it was: " + nextToken);

            // Get the next product and make sure it's not null
            this.nextObject = this.jsonParser.readValueAs(new TypeReference<Map<String, Object>>() { });
            if (this.nextObject == null) {
                throw new IllegalStateException("The next parsed object of the Json structure was null");
        } catch (final Exception e) {
            LOG.error("There was a problem initializing the next Object: " + e.getMessage(), e);
            throw new RuntimeException("There was a problem initializing the next Object: " + e.getMessage(), e);

    public boolean hasNext() {
        if (!this.isInitialized) {

        return this.nextObject != null;

    public Map<String, Object> next() {
        // This method will return the current object and initialize the next object so hasNext will always have knowledge of the current state

        // Makes sure we're initialized first
        if (!this.isInitialized) {

        // Store the current next object for return
        final Map<String, Object> currentNextObject = this.nextObject;

        // Initialize the next object

        return currentNextObject;

    public void close() throws IOException {


If you don't care about memory usage, then it would certainly be easier to read the entire file and parse it as one big Json as mentioned in other answers.

How can I select records ONLY from yesterday?

to_char(tran_date, 'yyyy-mm-dd') = to_char(sysdate-1, 'yyyy-mm-dd')

check null,empty or undefined angularjs

You can also do a simple check using function,

$scope.isNullOrEmptyOrUndefined = function (value) {
    return !value;

How do I get into a non-password protected Java keystore or change the password?

The password of keystore by default is: "changeit". I functioned to my commands you entered here, for the import of the certificate. I hope you have already solved your problem.

Build and Install unsigned apk on device without the development server?

It can be possible to generate an unsigned apk version for testing purpose so you can run on your mobile.

Initially i got the red screen errors as most mentioned here. but i followed the same which was mentioned here and it worked for me.

On your console from working directory, run these four commands

react-native bundle --dev false --platform android --entry-file index.js --bundle-output ./android/app/build/intermediates/assets/debug/ --assets-dest ./android/app/build/intermediates/res/merged/debug

cd android

gradlew assembleDebug

gradlew assembleRelease

And then APK file will produce on : android\app\build\outputs\apk\debug\app-debug.apk

SQL Server database restore error: specified cast is not valid. (SqlManagerUI)

Finally got this error to go away on a restore. I moved to SQL2012 out of frustration, but I guess this would probably still work on 2008R2. I had to use the logical names:

FROM DISK = ‘location of your.bak file’

And from there I ran a restore statement with MOVE using logical names.

FROM DISK = '\\database path\database.bak'
MOVE 'File_Data' TO 'E:\location\database.mdf',
MOVE 'File_DOCS' TO 'E:\location\database_1.ndf',
MOVE 'file' TO 'E:\location\database_2.ndf',
MOVE 'file' TO 'E:\location\database_3.ndf',
MOVE 'file_Log' TO 'E:\location\database.ldf'

When it was done restoring, I almost wept with joy.

Good luck!

C programming: Dereferencing pointer to incomplete type error

How did you actually define the structure? If

struct {
  char name[32];
  int  size;
  int  start;
  int  popularity;
} stasher_file;

is to be taken as type definition, it's missing a typedef. When written as above, you actually define a variable called stasher_file, whose type is some anonymous struct type.


typedef struct { ... } stasher_file;

(or, as already mentioned by others):

struct stasher_file { ... };

The latter actually matches your use of the type. The first form would require that you remove the struct before variable declarations.

How do I kill background processes / jobs when my shell script exits?

So script the loading of the script. Run a killall (or whatever is available on your OS) command that executes as soon as the script is finished.

Bash scripting missing ']'


if [ -s "p1"];  #line 13


if [ -s "p1" ];  #line 13

note the space.

How to assign more memory to docker container

If you want to change the default container and you are using Virtualbox, you can do it via the commandline / CLI:

docker-machine stop
VBoxManage modifyvm default --cpus 2
VBoxManage modifyvm default --memory 4096
docker-machine start

How do you get the contextPath from JavaScript, the right way?

I think you can achieve what you are looking for by combining number 1 with calling a function like in number 3.

You don't want to execute scripts on page load and prefer to call a function later on? Fine, just create a function that returns the value you would have set in a variable:

function getContextPath() {
   return "<%=request.getContextPath()%>";

It's a function so it wont be executed until you actually call it, but it returns the value directly, without a need to do DOM traversals or tinkering with URLs.

At this point I agree with @BalusC to use EL:

function getContextPath() {
   return "${pageContext.request.contextPath}";

or depending on the version of JSP fallback to JSTL:

function getContextPath() {
   return "<c:out value="${pageContext.request.contextPath}" />";

Populate a Drop down box from a mySQL table in PHP

After a while of research and disappointments....I was able to make this up

     <?php $conn = new mysqli('hostname', 'username', 'password','dbname') or die ('Cannot connect to db') $result = $conn->query("select * from table");?>

//insert the below code in the body

    <table id="myTable"> <tr class="header"> <th style="width:20%;">Name</th>
    <th style="width:20%;">Email</th>
       <th style="width:10%;">City/ Region</th>
        <th style="width:30%;">Details</th>
   while ($row = mysqli_fetch_array($result)) {

               echo "<tr>";
               echo "<td>".$row['username']."</td>";
               echo "<td>".$row['city']."</td>";
                echo "<td>".$row['details']."</td>";
               echo "</tr>";


Trust me it works :)

Load different application.yml in SpringBoot Test

Lu55 Option 1 how to...

Add test only application.yml inside a seperated resources folder.

+-- main
¦   +-- java
¦   +-- resources
¦       +-- application.yml
+-- test
    +-- java
    +-- resources
        +-- application.yml

In this project structure the application.yml under main is loaded if the code under main is running, the application.yml under test is used in a test.

To setup this structure add a new Package folder test/recources if not present.

Eclipse right click on your project -> Properties -> Java Build Path -> Source Tab -> (Dialog ont the rigth side) "Add Folder ..."

Inside Source Folder Selection -> mark test -> click on "Create New Folder ..." button -> type "resources" inside the Textfeld -> Click the "Finish" button.

After pushing the "Finisch" button you can see the sourcefolder {projectname}/src/test/recources (new)

Optional: Arrange folder sequence for the Project Explorer view. Klick on Order and Export Tab mark and move {projectname}/src/test/recources to bottom. Apply and Close

!!! Clean up Project !!!
Eclipse -> Project -> Clean ...

Now there is a separated yaml for test and the main application.

Dynamically add event listener

Renderer has been deprecated in Angular 4.0.0-rc.1, read the update below

The angular2 way is to use listen or listenGlobal from Renderer

For example, if you want to add a click event to a Component, you have to use Renderer and ElementRef (this gives you as well the option to use ViewChild, or anything that retrieves the nativeElement)

constructor(elementRef: ElementRef, renderer: Renderer) {

    // Listen to click events in the component
    renderer.listen(elementRef.nativeElement, 'click', (event) => {
      // Do something with 'event'

You can use listenGlobal that will give you access to document, body, etc.

renderer.listenGlobal('document', 'click', (event) => {
  // Do something with 'event'

Note that since beta.2 both listen and listenGlobal return a function to remove the listener (see breaking changes section from changelog for beta.2). This is to avoid memory leaks in big applications (see #6686).

So to remove the listener we added dynamically we must assign listen or listenGlobal to a variable that will hold the function returned, and then we execute it.

// listenFunc will hold the function returned by "renderer.listen"
listenFunc: Function;

// globalListenFunc will hold the function returned by "renderer.listenGlobal"
globalListenFunc: Function;

constructor(elementRef: ElementRef, renderer: Renderer) {
    // We cache the function "listen" returns
    this.listenFunc = renderer.listen(elementRef.nativeElement, 'click', (event) => {
        // Do something with 'event'

    // We cache the function "listenGlobal" returns
    this.globalListenFunc = renderer.listenGlobal('document', 'click', (event) => {
        // Do something with 'event'

ngOnDestroy() {
    // We execute both functions to remove the respectives listeners

    // Removes "listen" listener
    // Removs "listenGlobal" listener

Here's a plnkr with an example working. The example contains the usage of listen and listenGlobal.

Using RendererV2 with Angular 4.0.0-rc.1+ (Renderer2 since 4.0.0-rc.3)

  • 25/02/2017: Renderer has been deprecated, now we should use RendererV2 (see line below). See the commit.

  • 10/03/2017: RendererV2 was renamed to Renderer2. See the breaking changes.

RendererV2 has no more listenGlobal function for global events (document, body, window). It only has a listen function which achieves both functionalities.

For reference, I'm copy & pasting the source code of the DOM Renderer implementation since it may change (yes, it's angular!).

listen(target: 'window'|'document'|'body'|any, event: string, callback: (event: any) => boolean):
      () => void {
    if (typeof target === 'string') {
      return <() => void>this.eventManager.addGlobalEventListener(
          target, event, decoratePreventDefault(callback));
    return <() => void>this.eventManager.addEventListener(
               target, event, decoratePreventDefault(callback)) as() => void;

As you can see, now it verifies if we're passing a string (document, body or window), in which case it will use an internal addGlobalEventListener function. In any other case, when we pass an element (nativeElement) it will use a simple addEventListener

To remove the listener it's the same as it was with Renderer in angular 2.x. listen returns a function, then call that function.


// Add listeners
let global = this.renderer.listen('document', 'click', (evt) => {
  console.log('Clicking the document', evt);

let simple = this.renderer.listen(this.myButton.nativeElement, 'click', (evt) => {
  console.log('Clicking the button', evt);

// Remove listeners

plnkr with Angular 4.0.0-rc.1 using RendererV2

plnkr with Angular 4.0.0-rc.3 using Renderer2

JQuery Event for user pressing enter in a textbox?

heres a jquery plugin to do that

(function($) {
    $.fn.onEnter = function(func) {
        this.bind('keypress', function(e) {
            if (e.keyCode == 13) func.apply(this, [e]);    
        return this; 

to use it, include the code and set it up like this:

$( function () {
    $("input").onEnter( function() {
        $(this).val("Enter key pressed");                

jsfiddle of it here

What column type/length should I use for storing a Bcrypt hashed password in a Database?

If you are using PHP's password_hash() with the PASSWORD_DEFAULT algorithm to generate the bcrypt hash (which I would assume is a large percentage of people reading this question) be sure to keep in mind that in the future password_hash() might use a different algorithm as the default and this could therefore affect the length of the hash (but it may not necessarily be longer).

From the manual page:

Note that this constant is designed to change over time as new and stronger algorithms are added to PHP. For that reason, the length of the result from using this identifier can change over time. Therefore, it is recommended to store the result in a database column that can expand beyond 60 characters (255 characters would be a good choice).

Using bcrypt, even if you have 1 billion users (i.e. you're currently competing with facebook) to store 255 byte password hashes it would only ~255 GB of data - about the size of a smallish SSD hard drive. It is extremely unlikely that storing the password hash is going to be the bottleneck in your application. However in the off chance that storage space really is an issue for some reason, you can use PASSWORD_BCRYPT to force password_hash() to use bcrypt, even if that's not the default. Just be sure to stay informed about any vulnerabilities found in bcrypt and review the release notes every time a new PHP version is released. If the default algorithm is ever changed it would be good to review why and make an informed decision whether to use the new algorithm or not.

How to compare two dates to find time difference in SQL Server 2005, date manipulation

I think you need the time gap between job_start & job_end.

Try this...

select SUBSTRING(CONVERT(VARCHAR(20),(job_end - job_start),120),12,8) from tableA

I ended up with this.


How to horizontally align ul to center of div?

Make the left and right margins of your UL auto and assign it a width:

#headermenu ul {
    margin: 0 auto;
    width: 620px;

Edit: As kleinfreund has suggested, you can also center align the container and give the ul an inline-block display, but you then also have to give the LIs either a left float or an inline display.

#headermenu { 
    text-align: center;
#headermenu ul { 
    display: inline-block;
#headermenu ul li {
    float: left; /* or display: inline; */

What does /p mean in set /p?

The /P switch allows you to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. The promptString can be empty.

Two ways I've used it... first:

SET /P variable=

When batch file reaches this point (when left blank) it will halt and wait for user input. Input then becomes variable.

And second:

SET /P variable=<%temp%\filename.txt

Will set variable to contents (the first line) of the txt file. This method won't work unless the /P is included. Both tested on Windows 8.1 Pro, but it's the same on 7 and 10.

Align button to the right

Maybe you can use float:right;:

.one {_x000D_
  padding-left: 1em;_x000D_
  text-color: white;_x000D_
   display:inline; _x000D_
.two {_x000D_
  background-color: #00ffff;_x000D_
      <div class="row">_x000D_
       <h3 class="one">Text</h3>_x000D_
       <button class="btn btn-secondary pull-right">Button</button>_x000D_

Convert DataTable to CSV stream

Update 1

I have modified it to use StreamWriter instead, add an option to check if you need column headers in your output.

public static bool DataTableToCSV(DataTable dtSource, StreamWriter writer, bool includeHeader)
    if (dtSource == null || writer == null) return false;

    if (includeHeader)
        string[] columnNames = dtSource.Columns.Cast<DataColumn>().Select(column => "\"" + column.ColumnName.Replace("\"", "\"\"") + "\"").ToArray<string>();
        writer.WriteLine(String.Join(",", columnNames));

    foreach (DataRow row in dtSource.Rows)
        string[] fields = row.ItemArray.Select(field => "\"" + field.ToString().Replace("\"", "\"\"") + "\"").ToArray<string>();
        writer.WriteLine(String.Join(",", fields));

    return true;

As you can see, you can choose the output by initial StreamWriter, if you use StreamWriter(Stream BaseStream), you can write csv into MemeryStream, FileStream, etc.


I have an easy datatable to csv function, it serves me well:

    public static void DataTableToCsv(DataTable dt, string csvFile)
        StringBuilder sb = new StringBuilder();

        var columnNames = dt.Columns.Cast<DataColumn>().Select(column => "\"" + column.ColumnName.Replace("\"", "\"\"") + "\"").ToArray();
        sb.AppendLine(string.Join(",", columnNames));

        foreach (DataRow row in dt.Rows)
            var fields = row.ItemArray.Select(field => "\"" + field.ToString().Replace("\"", "\"\"") + "\"").ToArray();
            sb.AppendLine(string.Join(",", fields));

        File.WriteAllText(csvFile, sb.ToString(), Encoding.Default);

MySQL Select Date Equal to Today

Sounds like you need to add the formatting to the WHERE:

SELECT, DATE_FORMAT(users.signup_date, '%Y-%m-%d') 
FROM users 
WHERE DATE_FORMAT(users.signup_date, '%Y-%m-%d') = CURDATE()

See SQL Fiddle with Demo

Filtering a spark dataframe based on date

In PySpark(python) one of the option is to have the column in unix_timestamp format.We can convert string to unix_timestamp and specify the format as shown below. Note we need to import unix_timestamp and lit function

from pyspark.sql.functions import unix_timestamp, lit

df.withColumn("tx_date", to_date(unix_timestamp(df_cast["date"], "MM/dd/yyyy").cast("timestamp")))

Now we can apply the filters

df_cast.filter(df_cast["tx_date"] >= lit('2017-01-01')) \
       .filter(df_cast["tx_date"] <= lit('2017-01-31')).show()

how to solve Error cannot add duplicate collection entry of type add with unique key attribute 'value' in iis 7

The ideal scenario is to have <add value="default.aspx" /> in config so the application can be deployed to any server without having to reconfigure. IMHO I think the implementation within IIS is poor.

We've used the following to make our default document setup more robust and as a result more SEO friendly by using canonical URL's:

        <remove value="default.aspx" />
        <add value="default.aspx" />

Works OK for us.

MySQL select all rows from last month until (now() - 1 month), for comparative purposes

FROM table 

See the docs for info on DATE_SUB, ADDDATE, LAST_DAY and other useful datetime functions.

How can I remove the "No file chosen" tooltip from a file input in Chrome?

I know it is a bit of a hack, but all I required was to set the color to transparent in the style sheet - inline would look like this style="color:transparent;".

Select elements by attribute

Do you mean can you select them? If so, then yes:


How can I easily add storage to a VirtualBox machine with XP installed?

For Windows users there's an additional user friendly option: CloneVDI Tool by mpack. It's a GUI front-end to VBoxManage that makes things a little easier to work with.

As Alexander M. mentioned, you'll still have to use GParted, Partition Magic or a similar partition editor to grow your partition to the newly allocated physical drive. To do this just download the GParted iso, mount it as a bootable drive in the VirtualBox and boot from it.

Call a Subroutine from a different Module in VBA

Prefix the call with Module2 (ex. Module2.IDLE). I'm assuming since you asked this that you have IDLE defined multiple times in the project, otherwise this shouldn't be necessary.

From Arraylist to Array

This is the best way (IMHO).

List<String> myArrayList = new ArrayList<String>();
String[] myArray = myArrayList.toArray(new String[myArrayList.size()]);

This code works also:

String[] myArray = myArrayList.toArray(new String[0]);

But it less effective: the string array is created twice: first time zero-length array is created, then the real-size array is created, filled and returned. So, if since you know the needed size (from list.size()) you should create array that is big enough to put all elements. In this case it is not re-allocated.

PHP foreach with Nested Array?

As I understand , all of previous answers , does not make an Array output, In my case : I have a model with parent-children structure (simplified code here):

public function parent(){

    return $this->belongsTo('App\Models\Accounting\accounting_coding', 'parent_id');

public function children()

    return $this->hasMany('App\Models\Accounting\accounting_coding', 'parent_id');

and if you want to have all of children IDs as an Array , This approach is fine and working for me :

public function allChildren()
    $allChildren = [];
    if ($this->has_branch) {

        foreach ($this->children as $child) {

            $subChildren = $child->allChildren();

            if (count($subChildren) == 1) {
                $allChildren  [] = $subChildren[0];
            } else if (count($subChildren) > 1) {
                $allChildren += $subChildren;
    $allChildren  [] = $this->id;//adds self Id to children Id list

    return $allChildren; 

the allChildren() returns , all of childrens as a simple Array .

What command shows all of the topics and offsets of partitions in Kafka?

You might want to try kt. It's also quite faster than the bundled kafka-topics.

This is the current most complete info description you can get out of a topic with kt:

kt topic -brokers localhost:9092 -filter my_topic_name -partitions -leaders -replicas

It also outputs as JSON, so you can pipe it to jq for further flexibility.

Count unique values in a column in Excel

You can do the following steps:

  1. First isolate the column (by inserting a blank column before and/or after the column you want to count the unique values if there are any adjacent columns;

  2. Then select the whole column, go to 'Data' > 'Advanced Filter' and check the checkbox 'Unique records only'. This will hide all non-unique records so you can count the unique ones by selecting the whole column.

onKeyDown event not working on divs in React

Using the div trick with tab_index="0" or tabIndex="-1" works, but any time the user is focusing a view that's not an element, you get an ugly focus-outline on the entire website. This can be fixed by setting the CSS for the div to use outline: none in the focus.

Here's the implementation with styled components:

import styled from "styled-components"

const KeyReceiver = styled.div`
  &:focus {
    outline: none;

and in the App class:

  render() {
    return (      
      <KeyReceiver onKeyDown={this.handleKeyPress} tabIndex={-1}>
          Display stuff...

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'

Request header field Access-Control-Allow-Headers is not allowed by Access-Control-Allow-Headers

Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers error means that Access-Control-Allow-Origin field of HTTP header is not handled or allowed by response. Remove Access-Control-Allow-Origin field from the request header.

can't load package: package .: no buildable Go source files

Another possible reason for the message:

can't load package: .... : no buildable Go source files

Is when the source files being compiled have:

// +build ignore

In which case the files are ignored and not buildable as requested.This behaviour is documented at

Windows batch: sleep

Microsoft has a sleep function you can call directly.

    Usage:  sleep      time-to-sleep-in-seconds
            sleep [-m] time-to-sleep-in-milliseconds
            sleep [-c] commited-memory ratio (1%-100%)

You can just say sleep 1 for example to sleep for 1 second in your batch script.

IMO Ping is a bit of a hack for this use case.

Android checkbox style

In the previous answer also in the section <selector>...</selector> you may need:

<item android:state_pressed="true" android:drawable="@drawable/checkbox_pressed" ></item>

Deserialize a JSON array in C#

This should work...

JavaScriptSerializer ser = new JavaScriptSerializer();
var records = new ser.Deserialize<List<Record>>(jsonData);

public class Person
    public string Name;
    public int Age;
    public string Location;
public class Record
    public Person record;

Why split the <script> tag when writing it with document.write()?

I think is for prevent the browser's HTML parser from interpreting the <script>, and mainly the </script> as the closing tag of the actual script, however I don't think that using document.write is a excellent idea for evaluating script blocks, why don't use the DOM...

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

Find an item in List by LINQ?

I used to use a Dictionary which is some sort of an indexed list which will give me exactly what I want when I want it.

Dictionary<string, int> margins = new Dictionary<string, int>();
margins.Add("left", 10);
margins.Add("right", 10);
margins.Add("top", 20);
margins.Add("bottom", 30);

Whenever I wish to access my margins values, for instance, I address my dictionary:

int xStartPos = margins["left"];
int xLimitPos = margins["right"];
int yStartPos = margins["top"];
int yLimitPos = margins["bottom"];

So, depending on what you're doing, a dictionary can be useful.

how to add the missing RANDR extension

I am seeing this error message when I run Firefox headless through selenium using xvfb. It turns out that the message was a red herring for me. The message is only a warning, not an error. It is not why Firefox was not starting correctly.

The reason that Firefox was not starting for me was that it had been updated to a version that was no longer compatible with the Selenium drivers that I was using. I upgraded the selenium drivers to the latest and Firefox starts up fine again (even with this warning message about RANDR).

New releases of Firefox are often only compatible with one or two versions of Selenium. Occasionally Firefox is released with NO compatible version of Selenium. When that happens, it may take a week or two for a new version of Selenium to get released. Because of this, I now keep a version of Firefox that is known to work with the version of Selenium that I have installed. In addition to the version of Firefox that is kept up to date by my package manager, I have a version installed in /opt/ (eg /opt/firefox31/). The Selenium Java API takes an argument for the location of the Firefox binary to be used. The downside is that older versions of Firefox have known security vulnerabilities and shouldn't be used with untrusted content.

What is an Endpoint?

All of the answers posted so far are correct, an endpoint is simply one end of a communication channel. In the case of OAuth, there are three endpoints you need to be concerned with:

  1. Temporary Credential Request URI (called the Request Token URL in the OAuth 1.0a community spec). This is a URI that you send a request to in order to obtain an unauthorized Request Token from the server / service provider.
  2. Resource Owner Authorization URI (called the User Authorization URL in the OAuth 1.0a community spec). This is a URI that you direct the user to to authorize a Request Token obtained from the Temporary Credential Request URI.
  3. Token Request URI (called the Access Token URL in the OAuth 1.0a community spec). This is a URI that you send a request to in order to exchange an authorized Request Token for an Access Token which can then be used to obtain access to a Protected Resource.

Hope that helps clear things up. Have fun learning about OAuth! Post more questions if you run into any difficulties implementing an OAuth client.

How do I convert a double into a string in C++?

You can use std::to_string in C++11

double d = 3.0;
std::string str = std::to_string(d);

HTML5 Form Input Pattern Currency Format

If you want to allow a comma delimiter which will pass the following test cases:

0,00  => true
0.00  => true
01,00 => true
01.00 => true
0.000 => false
0-01  => false

then use this:


Android Percentage Layout Height

android:layout_weight=".YOURVALUE" is best way to implement in percentage

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
    android:orientation="vertical" >

        android:text="@string/logText" >


Determine distance from the top of a div to top of window with javascript

I used this:

                              myElement = document.getElemenById("xyz");
Get_Offset_From_Start       ( myElement );  // returns positions from website's start position
Get_Offset_From_CurrentView ( myElement );  // returns positions from current scrolled view's TOP and LEFT


function Get_Offset_From_Start (object, offset) { 
    offset = offset || {x : 0, y : 0};
    offset.x += object.offsetLeft;       offset.y += object.offsetTop;
    if(object.offsetParent) {
        offset = Get_Offset_From_Start (object.offsetParent, offset);
    return offset;

function Get_Offset_From_CurrentView (myElement) {
    if (!myElement) return;
    var offset = Get_Offset_From_Start (myElement);
    var scrolled = GetScrolled (myElement.parentNode);
    var posX = offset.x - scrolled.x;   var posY = offset.y - scrolled.y;
    return {lefttt: posX , toppp: posY };
function GetScrolled (object, scrolled) {
    scrolled = scrolled || {x : 0, y : 0};
    scrolled.x += object.scrollLeft;    scrolled.y += object.scrollTop;
    if (object.tagName.toLowerCase () != "html" && object.parentNode) { scrolled=GetScrolled (object.parentNode, scrolled); }
    return scrolled;

    // live monitoring
    window.addEventListener('scroll', function (evt) {
        var Positionsss =  Get_Offset_From_CurrentView(myElement);  

Using PowerShell to write a file in UTF-8 without the BOM

    [System.IO.FileInfo] $file = Get-Item -Path $FilePath 
    $sequenceBOM = New-Object System.Byte[] 3 
    $reader = $file.OpenRead() 
    $bytesRead = $reader.Read($sequenceBOM, 0, 3) 
    #A UTF-8+BOM string will start with the three following bytes. Hex: 0xEF0xBB0xBF, Decimal: 239 187 191 
    if ($bytesRead -eq 3 -and $sequenceBOM[0] -eq 239 -and $sequenceBOM[1] -eq 187 -and $sequenceBOM[2] -eq 191) 
        $utf8NoBomEncoding = New-Object System.Text.UTF8Encoding($False) 
        [System.IO.File]::WriteAllLines($FilePath, (Get-Content $FilePath), $utf8NoBomEncoding) 
        Write-Host "Remove UTF-8 BOM successfully" 
        Write-Warning "Not UTF-8 BOM file" 

Source How to remove UTF8 Byte Order Mark (BOM) from a file using PowerShell

How do I download a file from the internet to my linux server with Bash

I guess you could use curl and wget, but since Oracle requires you to check of some checkmarks this will be painfull to emulate with the tools mentioned. You would have to download the page with the license agreement and from looking at it figure out what request is needed to get to the actual download.

Of course you could simply start a browser, but this might not qualify as 'from the command line'. So you might want to look into lynx, a text based browser.