Programs & Examples On #Unbuffered queries

How to bind 'touchstart' and 'click' events but not respond to both?

I succeeded by the following way.

Easy Peasy...

$(this).on('touchstart click', function(e){
  //do your stuff here

Css pseudo classes input:not(disabled)not:[type="submit"]:focus

Your syntax is pretty screwy.

Change this:




Seems that many people don't realize :enabled and :disabled are valid CSS selectors...

string comparison in batch file

The solution is DO NOT USE SPACES!

IF "%DevEnvDir%"=="C:\" (

Detect merged cells in VBA Excel with MergeArea

While working with selected cells as shown by @tbur can be useful, it's also not the only option available.

You can use Range() like so:

If Worksheets("Sheet1").Range("A1").MergeCells Then
  Do something
  Do something else
End If


If Worksheets("Sheet1").Range("A1:C1").MergeCells Then
  Do something
  Do something else
End If

Alternately, you can use Cells():

If Worksheets("Sheet1").Cells(1, 1).MergeCells Then
  Do something
  Do something else
End If

Scroll event listener javascript

I was looking a lot to find a solution for sticy menue with old school JS (without JQuery). So I build small test to play with it. I think it can be helpfull to those looking for solution in js. It needs improvments of unsticking the menue back, and making it more smooth. Also I find a nice solution with JQuery that clones the original div instead of position fixed, its better since the rest of page element dont need to be replaced after fixing. Anyone know how to that with JS ? Please remark, correct and improve.

<!DOCTYPE html>


// addEvent function by John Resig:

function addEvent( obj, type, fn ) {

    if ( obj.attachEvent ) {

        obj['e'+type+fn] = fn;
        obj[type+fn] = function(){obj['e'+type+fn]( window.event );};
        obj.attachEvent( 'on'+type, obj[type+fn] );
    } else {
        obj.addEventListener( type, fn, false );
function getScrollY() {
    var  scrOfY = 0;
    if( typeof( window.pageYOffset ) == 'number' ) {
        //Netscape compliant
        scrOfY = window.pageYOffset;

    } else if( document.body && document.body.scrollTop )  {
        //DOM compliant
        scrOfY = document.body.scrollTop;
    return scrOfY;
#mydiv {
#fdiv {


<!-- HTML for example event goes here -->

<div id="fdiv" style="background-color:red;position:fix">
<div id="mydiv" style="background-color:yellow">
<div id="fdiv" style="background-color:green">


// Script for example event goes here

addEvent(window, 'scroll', function(event) {

    var x = document.getElementById("mydiv");

    var y = getScrollY();      
    if (y >= 100) { = "fixed"; "0";


Nested routes with react router v4 / v5

Just wanted to mention react-router v4 changed radically since this question was posted/answed.

There is no <Match> component any more! <Switch>is to make sure only the first match is rendered. <Redirect> well .. redirects to another route. Use or leave out exact to either in- or exclude a partial match.

See the docs. They are great.

Here's an example I hope is useable to answer your question.

    <Redirect exact from='/' to='/front'/>
    <Route path="/" render={() => {
      return (
          <h2>Home menu</h2>
          <Link to="/front">front</Link>
          <Link to="/back">back</Link>
    }} />          
    <Route path="/front" render={() => {
      return (
        <h2>front menu</h2>
        <Link to="/front/help">help</Link>
        <Link to="/front/about">about</Link>
    }} />
    <Route exact path="/front/help" render={() => {
      return <h2>front help</h2>;
    }} />
    <Route exact path="/front/about" render={() => {
      return <h2>front about</h2>;
    }} />
    <Route path="/back" render={() => {
      return (
        <h2>back menu</h2>
        <Link to="/back/help">help</Link>
        <Link to="/back/about">about</Link>
    }} />
    <Route exact path="/back/help" render={() => {
      return <h2>back help</h2>;
    }} />
    <Route exact path="/back/about" render={() => {
      return <h2>back about</h2>;
    }} />

Hope it helped, let me know. If this example is not answering your question well enough, tell me and I'll see if I can modify it.

How to put a symbol above another in LaTeX?

Use \overset{above}{main} in math mode. In your case, \overset{a}{\#}.

Making a div vertically scrollable using CSS

Try like this.

<div style="overflow-y: scroll; height:400px;">

How to remove certain characters from a string in C++?

For those of you that prefer a more concise, easier to read lambda coding style...

This example removes all non-alphanumeric and white space characters from a wide string. You can mix it up with any of the other ctype.h helper functions to remove complex-looking character-based tests.

(I'm not sure how these functions would handle CJK languages, so walk softly there.)

    // Boring C loops: 'for(int i=0;i<str.size();i++)' 
    // Boring C++ eqivalent: 'for(iterator iter=c.begin; iter != c.end; ++iter)'

See if you don't find this easier to understand than noisy C/C++ for/iterator loops:

TSTRING label = _T("1.   Replen & Move  RPMV");
TSTRING newLabel = label;
set<TCHAR> badChars; // Use ispunct, isalpha, isdigit, (lambda version, with capture list parameter(s) example; handiest thing since sliced bread)
for_each(label.begin(), label.end(), [&badChars](TCHAR n){
    if (!isalpha(n) && !isdigit(n))

for_each(badChars.begin(), badChars.end(), [&newLabel](TCHAR n){
    newLabel.erase(std::remove(newLabel.begin(), newLabel.end(), n), newLabel.end());

newLabel results after running this code: "1ReplenMoveRPMV"

This is just academic, since it would clearly be more precise, concise and efficient to combine the 'if' logic from lambda0 (first for_each) into the single lambda1 (second for_each), if you have already established which characters are the "badChars".

How do I abort/cancel TPL Tasks?

Like this post suggests, this can be done in the following way:

int Foo(CancellationToken token)
    Thread t = Thread.CurrentThread;
    using (token.Register(t.Abort))
        // compute-bound work here

Although it works, it's not recommended to use such approach. If you can control the code that executes in task, you'd better go with proper handling of cancellation.

How to get the input from the Tkinter Text Widget?

To get Tkinter input from the text box, you must add a few more attributes to the normal .get() function. If we have a text box myText_Box, then this is the method for retrieving its input.

def retrieve_input():
    input = self.myText_Box.get("1.0",END)

The first part, "1.0" means that the input should be read from line one, character zero (ie: the very first character). END is an imported constant which is set to the string "end". The END part means to read until the end of the text box is reached. The only issue with this is that it actually adds a newline to our input. So, in order to fix it we should change END to end-1c(Thanks Bryan Oakley) The -1c deletes 1 character, while -2c would mean delete two characters, and so on.

def retrieve_input():
    input = self.myText_Box.get("1.0",'end-1c')

How to assign text size in sp value using java code


Can someone give an example of cosine similarity, in a very simple, graphical way?

This Python code is my quick and dirty attempt to implement the algorithm:

import math
from collections import Counter

def build_vector(iterable1, iterable2):
    counter1 = Counter(iterable1)
    counter2 = Counter(iterable2)
    all_items = set(counter1.keys()).union(set(counter2.keys()))
    vector1 = [counter1[k] for k in all_items]
    vector2 = [counter2[k] for k in all_items]
    return vector1, vector2

def cosim(v1, v2):
    dot_product = sum(n1 * n2 for n1, n2 in zip(v1, v2) )
    magnitude1 = math.sqrt(sum(n ** 2 for n in v1))
    magnitude2 = math.sqrt(sum(n ** 2 for n in v2))
    return dot_product / (magnitude1 * magnitude2)

l1 = "Julie loves me more than Linda loves me".split()
l2 = "Jane likes me more than Julie loves me or".split()

v1, v2 = build_vector(l1, l2)
print(cosim(v1, v2))

How to force uninstallation of windows service

Have you try stopping the service before calling uninstall? I had this problem randomly. Sometime I could remove it without restarting. My guess is that it has to do with the service still running

Swift - iOS - Dates and times in different format

You have already found NSDateFormatter, just read the documentation on it.

NSDateFormatter Class Reference

For format character definitions
See: ICU Formatting Dates and Times
Also: Date Field SymbolTable..

TypeError: 'dict' object is not callable

You need to use:


Note the square brackets!

Animate text change in UILabel

Here is the code to make this work.

[UIView beginAnimations:@"animateText" context:nil];
[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];
[UIView setAnimationDuration:1.0f];
[self.lbl setAlpha:0];
[self.lbl setText:@"New Text";
[self.lbl setAlpha:1];
[UIView commitAnimations];

How to get all count of mongoose model?

Background for the solution

As stated in the mongoose documentation and in the answer by Benjamin, the method Model.count() is deprecated. Instead of using count(), the alternatives are the following:

Model.countDocuments(filterObject, callback)

Counts how many documents match the filter in a collection. Passing an empty object {} as filter executes a full collection scan. If the collection is large, the following method might be used.


This model method estimates the number of documents in the MongoDB collection. This method is faster than the previous countDocuments(), because it uses collection metadata instead of going through the entire collection. However, as the method name suggests, and depending on db configuration, the result is an estimate as the metadata might not reflect the actual count of documents in a collection at the method execution moment.

Both methods return a mongoose query object, which can be executed in one of the following two ways. Use .exec() if you want to execute a query at a later time.

The solution

Option 1: Pass a callback function

For example, count all documents in a collection using .countDocuments():

someModel.countDocuments({}, function(err, docCount) {
    if (err) { return handleError(err) } //handle possible errors
    //and do some other fancy stuff

Or, count all documents in a collection having a certain name using .countDocuments():

someModel.countDocuments({ name: 'Snow' }, function(err, docCount) {
    //see other example

Option 2: Use .then()

A mongoose query has .then() so it’s “thenable”. This is for a convenience and query itself is not a promise.

For example, count all documents in a collection using .estimatedDocumentCount():

    .then(docCount => {
        //and do one super neat trick
    .catch(err => {
        //handle possible errors

Option 3: Use async/await

When using async/await approach, the recommended way is to use it with .exec() as it provides better stack traces.

const docCount = await someModel.countDocuments({}).exec();

Learning by stackoverflowing,

How to use FormData in react-native?

Usage of formdata in react-native

I have used react-native-image-picker to select photo. In my case after choosing the photp from mobile. I'm storing it's info in component state. After, I'm sending POST request using fetch like below

const profile_pic = {
  name: this.state.formData.profile_pic.fileName,
  type: this.state.formData.profile_pic.type,
  path: this.state.formData.profile_pic.path,
  uri: this.state.formData.profile_pic.uri,
const formData = new FormData()
formData.append('first_name', this.state.formData.first_name);
formData.append('last_name', this.state.formData.last_name);
formData.append('profile_pic', profile_pic);
const Token = 'secret'

fetch('', {
    method: "POST",
    headers: {
      Accept: "application/json",
      "Content-Type": "multipart/form-data",
      Authorization: `Token ${Token}`
    body: formData
  .then(response => console.log(response.json()))

How unique is UUID?

For UUID4 I make it that there are approximately as many IDs as there are grains of sand in a cube-shaped box with sides 360,000km long. That's a box with sides ~2 1/2 times longer than Jupiter's diameter.

Working so someone can tell me if I've messed up units:

  • volume of grain of sand 0.00947mm^3 (Guardian)
  • UUID4 has 122 random bits -> 5.3e36 possible values (wikipedia)
  • volume of that many grains of sand = 5.0191e34 mm^3 or 5.0191e+25m^3
  • side length of cubic box with that volume = 3.69E8m or 369,000km
  • diameter of Jupiter: 139,820km (google)

Extract part of a regex match'<title>(.*)</title>', s, re.IGNORECASE).group(1)

How do I get the calling method name and type using reflection?

Technically, you can use StackTrace, but this is very slow and will not give you the answers you expect a lot of the time. This is because during release builds optimizations can occur that will remove certain method calls. Hence you can't be sure in release whether stacktrace is "correct" or not.

Really, there isn't any foolproof or fast way of doing this in C#. You should really be asking yourself why you need this and how you can architect your application, so you can do what you want without knowing which method called it.

Joining three tables using MySQL

CONCAT(employees.f_name," ",employees.l_name) AS   'Full Name', genders.gender_name AS 'Sex', 
depts.dept_name AS 'Team Name', 
pay_grades.pay_grade_name AS 'Band', 
designations.designation_name AS 'Role' 
FROM employees 
LEFT JOIN genders ON employees.gender_id = 
LEFT JOIN depts ON employees.dept_id = 
LEFT JOIN pay_grades ON employees.pay_grade_id = 
LEFT JOIN designations ON employees.designation_id = 

You can JOIN multiple TABLES like this example above.

jQuery select child element by class with unknown path

According to this documentation, the find method will search down through the tree of elements until it finds the element in the selector parameters. So $(parentSelector).find(childSelector) is the fastest and most efficient way to do this.

How to get controls in WPF to fill available space?

Each control deriving from Panel implements distinct layout logic performed in Measure() and Arrange():

  • Measure() determines the size of the panel and each of its children
  • Arrange() determines the rectangle where each control renders

The last child of the DockPanel fills the remaining space. You can disable this behavior by setting the LastChild property to false.

The StackPanel asks each child for its desired size and then stacks them. The stack panel calls Measure() on each child, with an available size of Infinity and then uses the child's desired size.

A Grid occupies all available space, however, it will set each child to their desired size and then center them in the cell.

You can implement your own layout logic by deriving from Panel and then overriding MeasureOverride() and ArrangeOverride().

See this article for a simple example.

How to create timer in angular2

Found a npm package that makes this easy with RxJS as a service.

You can 'subscribe' to an existing timer so you don't create a bazillion timers if you're using it many times in the same component.

How do I check if a string contains a specific word?

A simpler option:

return ( ! empty($a) && strpos($a, 'are'))? true : false;

The project type is not supported by this installation

If you are using VS 2010 and it is a ASP.NET project make sure you have the Visual Developer installed from the VS 2010 CD. This is not the free one, but part of what is required to work on ASP.NET projects in Visual Studio.

Where to put a textfile I want to use in eclipse?


Please try this

  1. In eclipse "Right click" on the text file u wanna use, see and copy the complete path stored in HDD like (if in UNIX "/home/sjaisawal/Space-11.4-template/provisioning/devenv/Test/src/testpath/testfile.txt")

  2. put this complete path and try.

  3. if it works then class-path issue else GOK :)

Java Webservice Client (Best way)

You can find some resources related to developing web services client using Apache axis2 here.

Below posts gives good explanations about developing web services using Apache axis2.

Pandas groupby month and year

You can also do it by creating a string column with the year and month as follows:

df['date'] = df.index
df['year-month'] = df['date'].apply(lambda x: str(x.year) + ' ' + str(x.month))
grouped = df.groupby('year-month')

However this doesn't preserve the order when you loop over the groups, e.g.

for name, group in grouped:

Will give:

2007 11
2007 12
2008 1
2008 10
2008 11
2008 12
2008 2
2008 3
2008 4
2008 5
2008 6
2008 7
2008 8
2008 9
2009 1
2009 10

So then, if you want to preserve the order, you must do as suggested by @Q-man above:

grouped = df.groupby([df.index.year, df.index.month])

This will preserve the order in the above loop:

(2007, 11)
(2007, 12)
(2008, 1)
(2008, 2)
(2008, 3)
(2008, 4)
(2008, 5)
(2008, 6)
(2008, 7)
(2008, 8)
(2008, 9)
(2008, 10)

TypeScript - Append HTML to container element in Angular 2

When working with Angular the recent update to Angular 8 introduced that a static property inside @ViewChild() is required as stated here and here. Then your code would require this small change:

@ViewChild('one') d1:ElementRef;


// query results available in ngOnInit
@ViewChild('one', {static: true}) foo: ElementRef;


// query results available in ngAfterViewInit
@ViewChild('one', {static: false}) foo: ElementRef;

Understanding events and event handlers in C#

C# knows two terms, delegate and event. Let's start with the first one.


A delegate is a reference to a method. Just like you can create a reference to an instance:

MyClass instance = myFactory.GetInstance();

You can use a delegate to create an reference to a method:

Action myMethod = myFactory.GetInstance;

Now that you have this reference to a method, you can call the method via the reference:

MyClass instance = myMethod();

But why would you? You can also just call myFactory.GetInstance() directly. In this case you can. However, there are many cases to think about where you don't want the rest of the application to have knowledge of myFactory or to call myFactory.GetInstance() directly.

An obvious one is if you want to be able to replace myFactory.GetInstance() into myOfflineFakeFactory.GetInstance() from one central place (aka factory method pattern).

Factory method pattern

So, if you have a TheOtherClass class and it needs to use the myFactory.GetInstance(), this is how the code will look like without delegates (you'll need to let TheOtherClass know about the type of your myFactory):

TheOtherClass toc;

class TheOtherClass
   public void SetFactory(MyFactory factory)
      // set here


If you'd use delegates, you don't have to expose the type of my factory:

TheOtherClass toc;
Action factoryMethod = myFactory.GetInstance;

class TheOtherClass
   public void SetFactoryMethod(Action factoryMethod)
      // set here


Thus, you can give a delegate to some other class to use, without exposing your type to them. The only thing you're exposing is the signature of your method (how many parameters you have and such).

"Signature of my method", where did I hear that before? O yes, interfaces!!! interfaces describe the signature of a whole class. Think of delegates as describing the signature of only one method!

Another large difference between an interface and a delegate is that when you're writing your class, you don't have to say to C# "this method implements that type of delegate". With interfaces, you do need to say "this class implements that type of an interface".

Further, a delegate reference can (with some restrictions, see below) reference multiple methods (called MulticastDelegate). This means that when you call the delegate, multiple explicitly-attached methods will be executed. An object reference can always only reference to one object.

The restrictions for a MulticastDelegate are that the (method/delegate) signature should not have any return value (void) and the keywords out and ref is not used in the signature. Obviously, you can't call two methods that return a number and expect them to return the same number. Once the signature complies, the delegate is automatically a MulticastDelegate.


Events are just properties (like the get;set; properties to instance fields) which expose subscription to the delegate from other objects. These properties, however, don't support get;set;. Instead, they support add; remove;

So you can have:

    Action myField;

    public event Action MyProperty
        add { myField += value; }
        remove { myField -= value; }

Usage in UI (WinForms,WPF,UWP So on)

So, now we know that a delegate is a reference to a method and that we can have an event to let the world know that they can give us their methods to be referenced from our delegate, and we are a UI button, then: we can ask anyone who is interested in whether I was clicked, to register their method with us (via the event we exposed). We can use all those methods that were given to us and reference them by our delegate. And then, we'll wait and wait.... until a user comes and clicks on that button, then we'll have enough reason to invoke the delegate. And because the delegate references all those methods given to us, all those methods will be invoked. We don't know what those methods do, nor we know which class implements those methods. All we do care about is that someone was interested in us being clicked, and gave us a reference to a method that complied with our desired signature.


Languages like Java don't have delegates. They use interfaces instead. The way they do that is to ask anyone who is interested in 'us being clicked', to implement a certain interface (with a certain method we can call), then give us the whole instance that implements the interface. We keep a list of all objects implementing this interface and can call their 'certain method we can call' whenever we get clicked.

IsNullOrEmpty with Object

Why would you need any other way? Comparing an Object reference with null is the least-verbose way to check if it's null.

jQuery .ajax() POST Request throws 405 (Method Not Allowed) on RESTful WCF

You can create the required headers in a filter too.

public class AllowAccessFilter implements Filter {
    public void doFilter(ServletRequest sRequest, ServletResponse sResponse, FilterChain chain) throws IOException, ServletException {
        System.out.println("in AllowAccessFilter.doFilter");
        HttpServletRequest request = (HttpServletRequest)sRequest;
        HttpServletResponse response = (HttpServletResponse)sResponse;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "GET, POST, PUT");
        response.setHeader("Access-Control-Allow-Headers", "Content-Type"); 
        chain.doFilter(request, response);

How to stop mongo DB in one command

From the given commands I think you're on Linux.

Start MongoDB:

$ sudo service mongod start
mongod start/running, process XXXXX 

Check the Status:

$ sudo service mongod status
mongod start/running, process XXXXX 

Stop MongoDB:

$ sudo service mongod stop
mongod stop/waiting 

Change first commit of project with Git?

As stated in 1.7.12 Release Notes, you may use

$ git rebase -i --root

How to kill a process running on particular port in Linux?

This prints to stdout the process ids of everything running on <port_number>:

fuser -n tcp <port_number> 

It also prints some stuff to stderr, so:

fuser -n tcp <port_number> 2> /dev/null

We can then supply these process ids to the kill command:

sudo kill $(fuser -n tcp <port_number> 2> /dev/null)

You could also put this in a function if you do it a lot:

function killport() {
    sudo kill $(fuser -n tcp $1 2> /dev/null)

Variable might not have been initialized error

Since no other answer has cited the Java language standard, I have decided to write an answer of my own:

In Java, local variables are not, by default, initialized with a certain value (unlike, for example, the field of classes). From the language specification one (§4.12.5) can read the following:

A local variable (§14.4, §14.14) must be explicitly given a value before it is used, by either initialization (§14.4) or assignment (§15.26), in a way that can be verified using the rules for definite assignment (§16 (Definite Assignment)).

Therefore, since the variables a and b are not initialized :

 for (int l= 0; l<x.length; l++) 
        if (x[l] == 0) 
        a++ ;
        else if (x[l] == 1) 
        b++ ;

the operations a++; and b++; could not produce any meaningful results, anyway. So it is logical for the compiler to notify you about it: variable a might not have been initialized
                a++ ;
                ^ variable b might not have been initialized
                b++ ;

However, one needs to understand that the fact that a++; and b++; could not produce any meaningful results has nothing to do with the reason why the compiler displays an error. But rather because it is explicitly set on the Java language specification that

A local variable (§14.4, §14.14) must be explicitly given a value (...)

To showcase the aforementioned point, let us change a bit your code to:

public static Rand searchCount (int[] x) 
    if(x == null || x.length  == 0)
      return null;
    int a ; 
    int b ; 


    for (int l= 0; l<x.length; l++) 
        if(l == 0)
           a = l;
        if(l == 1)
           b = l;


So even though the code above can be formally proven to be valid (i.e., the variables a and b will be always assigned with the value 0 and 1, respectively) it is not the compiler job to try to analyze your application's logic, and neither does the rules of local variable initialization rely on that. The compiler checks if the variables a and b are initialized according to the local variable initialization rules, and reacts accordingly (e.g., displaying a compilation error).

JPanel vs JFrame in Java

You should not extend the JFrame class unnecessarily (only if you are adding extra functionality to the JFrame class)


JFrame extends Component and Container.

It is a top level container used to represent the minimum requirements for a window. This includes Borders, resizability (is the JFrame resizeable?), title bar, controls (minimize/maximize allowed?), and event handlers for various Events like windowClose, windowOpened etc.


JPanel extends Component, Container and JComponent

It is a generic class used to group other Components together.

  • It is useful when working with LayoutManagers e.g. GridLayout f.i adding components to different JPanels which will then be added to the JFrame to create the gui. It will be more manageable in terms of Layout and re-usability.

  • It is also useful for when painting/drawing in Swing, you would override paintComponent(..) and of course have the full joys of double buffering.

A Swing GUI cannot exist without a top level container like (JWindow, Window, JFrame Frame or Applet), while it may exist without JPanels.

MySQL 'create schema' and 'create database' - Is there any difference

Mysql documentation says : CREATE SCHEMA is a synonym for CREATE DATABASE as of MySQL 5.0.2.

this all goes back to an ANSI standard for SQL in the mid-80s.

That standard had a "CREATE SCHEMA" command, and it served to introduce multiple name spaces for table and view names. All tables and views were created within a "schema". I do not know whether that version defined some cross-schema access to tables and views, but I assume it did. AFAIR, no product (at least back then) really implemented it, that whole concept was more theory than practice.

OTOH, ISTR this version of the standard did not have the concept of a "user" or a "CREATE USER" command, so there were products that used the concept of a "user" (who then had his own name space for tables and views) to implement their equivalent of "schema".

This is an area where systems differ.

As far as administration is concerned, this should not matter too much, because here you have differences anyway.

As far as you look at application code, you "only" have to care about cases where one application accesses tables from multiple name spaces. AFAIK, all systems support a syntax ".", and for this it should not matter whether the name space is that of a user, a "schema", or a "database".

How to use PrintWriter and File classes in Java?

The PrintWriter class can actually create the file for you.

This example works in JDK 1.7+.

// This will create the file.txt in your working directory.

PrintWriter printWriter = null;

try {

    printWriter = new PrintWriter("file.txt", "UTF-8");
    // The second parameter determines the encoding. It can be
    // any valid encoding, but I used UTF-8 as an example.

} catch (FileNotFoundException | UnsupportedEncodingException error) {

printWriter.println("Write whatever you like in your file.txt");

// Make sure to close the printWriter object otherwise nothing
// will be written to your file.txt and it will be blank.

For a list of valid encodings, see the documentation.

Alternatively, you can just pass the file path to the PrintWriter class without declaring the encoding.

mvn command is not recognized as an internal or external command

I'm using Maven 3+ version. In my case everything was fine. But while adding the M2_HOME along with bin directory, I missed the '\' at the end. Previously it was like: %M2_HOME%\bin , which was throwing the mvn not recognizable error. After adding "\" at the end, mvn started working fine. I guess "\" acts as pointer to next folder. "%M2_HOME%\bin\" Should work, if you missed it.

VBA code to show Message Box popup if the formula in the target cell exceeds a certain value

Essentially you want to add code to the Calculate event of the relevant Worksheet.

In the Project window of the VBA editor, double-click the sheet you want to add code to and from the drop-downs at the top of the editor window, choose 'Worksheet' and 'Calculate' on the left and right respectively.

Alternatively, copy the code below into the editor of the sheet you want to use:

Private Sub Worksheet_Calculate()

If Sheets("MySheet").Range("A1").Value > 0.5 Then
    MsgBox "Over 50%!", vbOKOnly
End If

End Sub

This way, every time the worksheet recalculates it will check to see if the value is > 0.5 or 50%.

Why is division in Ruby returning an integer instead of decimal value?

You can include the ruby mathn module.

require 'mathn'

This way, you are going to be able to make the division normally.

1/2              #=> (1/2)
(1/2) ** 3       #=> (1/8)
1/3*3            #=> 1
Math.sin(1/2)    #=> 0.479425538604203

This way, you get exact division (class Rational) until you decide to apply an operation that cannot be expressed as a rational, for example Math.sin.

C# int to enum conversion

You don't need the inheritance. You can do:


it will work ;)

Java - Check if JTextField is empty or not

you can use isEmpty() or isBlank() methods regarding what you need.

Returns true if, and only if, length() is 0.;

Returns true if the string is empty or contains only white space codepoints, otherwise false;

Calculate number of hours between 2 dates in PHP

Unfortunately the solution provided by FaileN doesn't work as stated by Walter Tross.. days may not be 24 hours!

I like to use the PHP Objects where possible and for a bit more flexibility I have come up with the following function:

 * @param DateTimeInterface $a
 * @param DateTimeInterface $b
 * @param bool              $absolute Should the interval be forced to be positive?
 * @param string            $cap The greatest time unit to allow
 * @return DateInterval The difference as a time only interval
function time_diff(DateTimeInterface $a, DateTimeInterface $b, $absolute=false, $cap='H'){

  // Get unix timestamps, note getTimeStamp() is limited
  $b_raw = intval($b->format("U"));
  $a_raw = intval($a->format("U"));

  // Initial Interval properties
  $h = 0;
  $m = 0;
  $invert = 0;

  // Is interval negative?
  if(!$absolute && $b_raw<$a_raw){
    $invert = 1;

  // Working diff, reduced as larger time units are calculated
  $working = abs($b_raw-$a_raw);

  // If capped at hours, calc and remove hours, cap at minutes
  if($cap == 'H') {
    $h = intval($working/3600);
    $working -= $h * 3600;
    $cap = 'M';

  // If capped at minutes, calc and remove minutes
  if($cap == 'M') {
    $m = intval($working/60);
    $working -= $m * 60;

  // Seconds remain
  $s = $working;

  // Build interval and invert if necessary
  $interval = new DateInterval('PT'.$h.'H'.$m.'M'.$s.'S');

  return $interval;

This like date_diff() creates a DateTimeInterval, but with the highest unit as hours rather than years.. it can be formatted as usual.

$interval = time_diff($date_a, $date_b);
echo $interval->format('%r%H'); // For hours (with sign)

N.B. I have used format('U') instead of getTimestamp() because of the comment in the manual. Also note that 64-bit is required for post-epoch and pre-negative-epoch dates!

List of <p:ajax> events

Schedule provides various ajax behavior events to respond user actions.

  • "dateSelect" org.primefaces.event.SelectEvent When a date is selected.
  • "eventSelect" org.primefaces.event.SelectEvent When an event is selected.
  • "eventMove" org.primefaces.event.ScheduleEntryMoveEvent When an event is moved.
  • "eventResize" org.primefaces.event.ScheduleEntryResizeEvent When an event is resized.
  • "viewChange" org.primefaces.event.SelectEvent When a view is changed.
  • "toggleSelect" org.primefaces.event.ToggleSelectEvent When toggle all checkbox changes
  • "expand" org.primefaces.event.NodeExpandEvent When a node is expanded.
  • "collapse" org.primefaces.event.NodeCollapseEvent When a node is collapsed.
  • "select" org.primefaces.event.NodeSelectEvent When a node is selected.-
  • "collapse" org.primefaces.event.NodeUnselectEvent When a node is unselected
  • "expand org.primefaces.event.NodeExpandEvent When a node is expanded.
  • "unselect" org.primefaces.event.NodeUnselectEvent When a node is unselected.
  • "colResize" org.primefaces.event.ColumnResizeEvent When a column is resized
  • "page" On pagination.
  • "sort" When a column is sorted.
  • "filter" On filtering.
  • "rowSelect" org.primefaces.event.SelectEvent When a row is being selected.
  • "rowUnselect" org.primefaces.event.UnselectEvent When a row is being unselected.
  • "rowEdit" org.primefaces.event.RowEditEvent When a row is edited.
  • "rowEditInit" org.primefaces.event.RowEditEvent When a row switches to edit mode
  • "rowEditCancel" org.primefaces.event.RowEditEvent When row edit is cancelled.
  • "colResize" org.primefaces.event.ColumnResizeEvent When a column is being selected.
  • "toggleSelect" org.primefaces.event.ToggleSelectEvent When header checkbox is toggled.
  • "colReorder" - When columns are reordered.
  • "rowSelectRadio" org.primefaces.event.SelectEvent Row selection with radio.
  • "rowSelectCheckbox" org.primefaces.event.SelectEvent Row selection with checkbox.
  • "rowUnselectCheckbox" org.primefaces.event.UnselectEvent Row unselection with checkbox.
  • "rowDblselect" org.primefaces.event.SelectEvent Row selection with double click.
  • "rowToggle" org.primefaces.event.ToggleEvent Row expand or collapse.
  • "contextMenu" org.primefaces.event.SelectEvent ContextMenu display.
  • "cellEdit" org.primefaces.event.CellEditEvent When a cell is edited.
  • "rowReorder" org.primefaces.event.ReorderEvent On row reorder.

there is more in here

A non well formed numeric value encountered

If the error is at the time of any calculation, double check that the values does not contains any comma(,). Values must be only in integer/ float format.

Getting the 'external' IP address in Java


How can I suppress the newline after a print statement?

Because python 3 print() function allows end="" definition, that satisfies the majority of issues.

In my case, I wanted to PrettyPrint and was frustrated that this module wasn't similarly updated. So i made it do what i wanted:

from pprint import PrettyPrinter

class CommaEndingPrettyPrinter(PrettyPrinter):
    def pprint(self, object):
        self._format(object, self._stream, 0, 0, {}, 0)
        # this is where to tell it what you want instead of the default "\n"

def comma_ending_prettyprint(object, stream=None, indent=1, width=80, depth=None):
    """Pretty-print a Python object to a stream [default is sys.stdout] with a comma at the end."""
    printer = CommaEndingPrettyPrinter(
        stream=stream, indent=indent, width=width, depth=depth)

Now, when I do:

comma_ending_prettyprint(row, stream=outfile)

I get what I wanted (substitute what you want -- Your Mileage May Vary)

MySQL: Get column name or alias from query

You could also use MySQLdb.cursors.DictCursor. This turns your result set into a python list of python dictionaries, although it uses a special cursor, thus technically less portable than the accepted answer. Not sure about speed. Here's the edited original code that uses this.

#!/usr/bin/python -u

import MySQLdb
import MySQLdb.cursors

# connect to mysql

    db = MySQLdb.connect(host='myhost', user='myuser', passwd='mypass', db='mydb', cursorclass=MySQLdb.cursors.DictCursor)
except MySQLdb.Error, e:
    print 'Error %d: %s' % (e.args[0], e.args[1])

# query select from table

cursor = db.cursor()

sql = 'SELECT ext, SUM(size) AS totalsize, COUNT(*) AS filecount FROM fileindex GROUP BY ext ORDER BY totalsize DESC;'

all_rows = cursor.fetchall()

print len(all_rows) # How many rows are returned.
for row in all_rows: # While loops always make me shudder!
    print '%s %s %s\n' % (row['ext'], row['totalsize'], row['filecount'])


Standard dictionary functions apply, for example, len(row[0]) to count the number of columns for the first row, list(row[0]) for a list of column names (for the first row), etc. Hope this helps!

how to avoid a new line with p tag?

The <p> paragraph tag is meant for specifying paragraphs of text. If you don't want the text to start on a new line, I would suggest you're using the <p> tag incorrectly. Perhaps the <span> tag more closely fits what you want to achieve...?

How to delete selected text in the vi editor

Highlighting with your mouse only highlights characters on the terminal. VI doesn't really get this information, so you have to highlight differently.

Press 'v' to enter a select mode, and use arrow keys to move that around. To delete, press x. To select lines at a time, press shift+v. To select blocks, try ctrl+v. That's good for, say, inserting lots of comment lines in front of your code :).

I'm OK with VI, but it took me a while to improve. My work mates recommended me this cheat sheet. I keep a printout on the wall for those odd moments when I forget something.

Happy hacking!

Use CSS to remove the space between images

Make them display: block in your CSS.

Div with margin-left and width:100% overflowing on the right side

A div is a block element and by default 100% wide. You should just have to set the textarea width to 100%.

std::thread calling method of class

Not so hard:

#include <thread>

void Test::runMultiThread()
    std::thread t1(&Test::calculate, this,  0, 10);
    std::thread t2(&Test::calculate, this, 11, 20);

If the result of the computation is still needed, use a future instead:

#include <future>

void Test::runMultiThread()
     auto f1 = std::async(&Test::calculate, this,  0, 10);
     auto f2 = std::async(&Test::calculate, this, 11, 20);

     auto res1 = f1.get();
     auto res2 = f2.get();

Ruby - ignore "exit" in code

loop {   begin   rescue SystemExit     p $!  #: #<SystemExit: exit>   end } 

This will print #<SystemExit: exit> in an infinite loop, without ever exiting.

EL access a map value by Integer key

Just another helpful hint in addition to the above comment would be when you have a string value contained in some variable such as a request parameter. In this case, passing this in will also result in JSTL keying the value of say "1" as a sting and as such no match being found in a Map hashmap.

One way to get around this is to do something like this.

<c:set var="longKey" value="${param.selectedIndex + 0}"/>

This will now be treated as a Long object and then has a chance to match an object when it is contained withing the map Map or whatever.

Then, continue as usual with something like


Column order manipulation using col-lg-push and col-lg-pull in Twitter Bootstrap 3

Pull "pulls" the div towards the left of the browser and and Push "pushes" the div away from left of browser.

Like: enter image description here

So basically in a 3 column layout of any web page the "Main Body" appears at the "Center" and in "Mobile" view the "Main Body" appears at the "Top" of the page. This is mostly desired by everyone with 3 column layout.

<div class="container">
    <div class="row">
        <div id="content" class="col-lg-4 col-lg-push-4 col-sm-12">
        <h2>This is Content</h2>
        <p>orem Ipsum ...</p>

        <div id="sidebar-left" class="col-lg-4  col-sm-6 col-lg-pull-4">
        <h2>This is Left Sidebar</h2>
        <p>orem Ipsum...</p>

        <div id="sidebar-right" class="col-lg-4 col-sm-6">
        <h2>This is Right Sidebar</h2>
        <p>orem Ipsum.... </p>

You can view it here:

Hope it helps

PDF Editing in PHP?

Tcpdf is also a good liabrary for generating pdf in php

Correct way to set Bearer token with CURL

This is a cURL function that can send or retrieve data. It should work with any PHP app that supports OAuth:

    function jwt_request($token, $post) {

       header('Content-Type: application/json'); // Specify the type of data
       $ch = curl_init(''); // Initialise cURL
       $post = json_encode($post); // Encode the data array into a JSON string
       $authorization = "Authorization: Bearer ".$token; // Prepare the authorisation token
       curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json' , $authorization )); // Inject the token into the header
       curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
       curl_setopt($ch, CURLOPT_POST, 1); // Specify the request method as POST
       curl_setopt($ch, CURLOPT_POSTFIELDS, $post); // Set the posted fields
       curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1); // This will follow any redirects
       $result = curl_exec($ch); // Execute the cURL statement
       curl_close($ch); // Close the cURL connection
       return json_decode($result); // Return the received data


Use it within one-way or two-way requests:

$token = "080042cad6356ad5dc0a720c18b53b8e53d4c274"; // Get your token from a cookie or database
$post = array('some_trigger'=>'...','some_values'=>'...'); // Array of data with a trigger
$request = jwt_request($token,$post); // Send or retrieve data

Table column sizing

As of Alpha 6 you can create the following sass file:

@each $breakpoint in map-keys($grid-breakpoints) {
  $infix: breakpoint-infix($breakpoint, $grid-breakpoints);

  col, td, th {
    @for $i from 1 through $grid-columns {
        &.col#{$infix}-#{$i} {
          flex: none;
          position: initial;

    @include media-breakpoint-up($breakpoint, $grid-breakpoints) {
      @for $i from 1 through $grid-columns {
        &.col#{$infix}-#{$i} {
          width: 100% / $grid-columns * $i;

TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT maximum storage sizes

Rising to @Ankan-Zerob's challenge, this is my estimate of the maximum length which can be stored in each text type measured in words:

      Type |         Bytes | English words | Multi-byte words
  TINYTEXT |           255 |           ±44 |              ±23
      TEXT |        65,535 |       ±11,000 |           ±5,900
MEDIUMTEXT |    16,777,215 |    ±2,800,000 |       ±1,500,000
  LONGTEXT | 4,294,967,295 |  ±740,000,000 |     ±380,000,000

In English, 4.8 letters per word is probably a good average (eg, though word lengths will vary according to domain (e.g. spoken language vs. academic papers), so there's no point being too precise. English is mostly single-byte ASCII characters, with very occasional multi-byte characters, so close to one-byte-per-letter. An extra character has to be allowed for inter-word spaces, so I've rounded down from 5.8 bytes per word. Languages with lots of accents such as say Polish would store slightly fewer words, as would e.g. German with longer words.

Languages requiring multi-byte characters such as Greek, Arabic, Hebrew, Hindi, Thai, etc, etc typically require two bytes per character in UTF-8. Guessing wildly at 5 letters per word, I've rounded down from 11 bytes per word.

CJK scripts (Hanzi, Kanji, Hiragana, Katakana, etc) I know nothing of; I believe characters mostly require 3 bytes in UTF-8, and (with massive simplification) they might be considered to use around 2 characters per word, so they would be somewhere between the other two. (CJK scripts are likely to require less storage using UTF-16, depending).

This is of course ignoring storage overheads etc.

Python Infinity - Any caveats?

Python's implementation follows the IEEE-754 standard pretty well, which you can use as a guidance, but it relies on the underlying system it was compiled on, so platform differences may occur. Recently¹, a fix has been applied that allows "infinity" as well as "inf", but that's of minor importance here.

The following sections equally well apply to any language that implements IEEE floating point arithmetic correctly, it is not specific to just Python.

Comparison for inequality

When dealing with infinity and greater-than > or less-than < operators, the following counts:

  • any number including +inf is higher than -inf
  • any number including -inf is lower than +inf
  • +inf is neither higher nor lower than +inf
  • -inf is neither higher nor lower than -inf
  • any comparison involving NaN is false (inf is neither higher, nor lower than NaN)

Comparison for equality

When compared for equality, +inf and +inf are equal, as are -inf and -inf. This is a much debated issue and may sound controversial to you, but it's in the IEEE standard and Python behaves just like that.

Of course, +inf is unequal to -inf and everything, including NaN itself, is unequal to NaN.

Calculations with infinity

Most calculations with infinity will yield infinity, unless both operands are infinity, when the operation division or modulo, or with multiplication with zero, there are some special rules to keep in mind:

  • when multiplied by zero, for which the result is undefined, it yields NaN
  • when dividing any number (except infinity itself) by infinity, which yields 0.0 or -0.0².
  • when dividing (including modulo) positive or negative infinity by positive or negative infinity, the result is undefined, so NaN.
  • when subtracting, the results may be surprising, but follow common math sense:
    • when doing inf - inf, the result is undefined: NaN;
    • when doing inf - -inf, the result is inf;
    • when doing -inf - inf, the result is -inf;
    • when doing -inf - -inf, the result is undefined: NaN.
  • when adding, it can be similarly surprising too:
    • when doing inf + inf, the result is inf;
    • when doing inf + -inf, the result is undefined: NaN;
    • when doing -inf + inf, the result is undefined: NaN;
    • when doing -inf + -inf, the result is -inf.
  • using math.pow, pow or ** is tricky, as it doesn't behave as it should. It throws an overflow exception when the result with two real numbers is too high to fit a double precision float (it should return infinity), but when the input is inf or -inf, it behaves correctly and returns either inf or 0.0. When the second argument is NaN, it returns NaN, unless the first argument is 1.0. There are more issues, not all covered in the docs.
  • math.exp suffers the same issues as math.pow. A solution to fix this for overflow is to use code similar to this:

        res = math.exp(420000)
    except OverflowError:
        res = float('inf')


Note 1: as an additional caveat, that as defined by the IEEE standard, if your calculation result under-or overflows, the result will not be an under- or overflow error, but positive or negative infinity: 1e308 * 10.0 yields inf.

Note 2: because any calculation with NaN returns NaN and any comparison to NaN, including NaN itself is false, you should use the math.isnan function to determine if a number is indeed NaN.

Note 3: though Python supports writing float('-NaN'), the sign is ignored, because there exists no sign on NaN internally. If you divide -inf / +inf, the result is NaN, not -NaN (there is no such thing).

Note 4: be careful to rely on any of the above, as Python relies on the C or Java library it was compiled for and not all underlying systems implement all this behavior correctly. If you want to be sure, test for infinity prior to doing your calculations.

¹) Recently means since version 3.2.
²) Floating points support positive and negative zero, so: x / float('inf') keeps its sign and -1 / float('inf') yields -0.0, 1 / float(-inf) yields -0.0, 1 / float('inf') yields 0.0 and -1/ float(-inf) yields 0.0. In addition, 0.0 == -0.0 is true, you have to manually check the sign if you don't want it to be true.

Find the number of columns in a table

   TABLE_NAME = 'table_name';

Loading a properties file from Java package

public class Test{  
  static {
   static Properties prop;
   private static void loadProperties() {
    prop = new Properties();
    InputStream in = Test.class
    try {
    } catch (IOException e) {


Sample database for exercise

If you want a big database of real data to play with, you could sign up for the Netflix Prize contest and get access to their data, which is pretty large (a few gigs of entries).

3rd party edit

The URL above does not contain the dataset anylonger (october 2016). The wikipedia page about the Netflix Prize reports that a law suit was settled regarding privacy concerns.

Enums in Javascript with ES6

This is my personal approach.

class ColorType {
    static get RED () {
        return "red";

    static get GREEN () {
        return "green";

    static get BLUE () {
        return "blue";

// Use case.
const color = Color.create(ColorType.RED);

Passing command line arguments to R CMD BATCH

I add an answer because I think a one line solution is always good! Atop of your myRscript.R file, add the following line:

eval(parse(text=paste(commandArgs(trailingOnly = TRUE), collapse=";")))

Then submit your script with something like:

R CMD BATCH [options] '--args arguments you want to supply' myRscript.R &

For example:

R CMD BATCH --vanilla '--args N=1 l=list(a=2, b="test") name="aname"' myscript.R &


> ls()
[1] "N"    "l"    "name"

ASP.NET Web API application gives 404 when deployed at IIS 7

For me, this issue was slightly different than other answers, as I was only receiving 404s on OPTIONS, yet I already had OPTIONS specifically stated in my Integrated Extensionless URL Handler options. Very confusing.

  1. As others have stated, runAllManagedModulesForAllRequests="true" in the modules node is an easy way to blanket-fix most Web API 404 issues - although I prefer @DavidAndroidDev 's answer which is much less intrusive. But there was something additional in my case.
  2. Unfortunately, I had this set in IIS under Request Filtering in the site:

OPTIONS Issue with Request Filtering

By adding the following security node to the web.config was necessary to knock that out - full system.webserver included for context:

    <modules runAllManagedModulesForAllRequests="true">
      <remove name="WebDAVModule" />
      <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
      <remove name="OPTIONSVerbHandler" />
      <remove name="TRACEVerbHandler" />
      <remove name="WebDAV" />
      <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
          <remove verb="OPTIONS" />

Although it's not the perfect answer for this question, it is the first result for "IIS OPTIONS 404" on Google, so I hope this helps someone out; cost me an hour today.

Start new Activity and finish current one in Android?

FLAG_ACTIVITY_NO_HISTORY when starting the activity you wish to finish after the user goes to another one.

How do I clone a specific Git branch?

git checkout -b <branch-name> <origin/branch_name>

for example in my case:

 git branch -a
* master

So to create a new branch based on my enum-account-number branch I do:

git checkout -b enum-account-number origin/enum-account-number

After you hit return the following happens:

Branch enum-account-number set up to track remote branch refs/remotes/origin/enum-account-number.
Switched to a new branch "enum-account-number"

jQuery UI Tabs - How to Get Currently Selected Tab Index

Another way to get the selected tab index is:

var index = jQuery('#tabs').data('tabs').options.selected;

How to do a FULL OUTER JOIN in MySQL?

MySql does not have FULL-OUTER-JOIN syntax. You have to emulate by doing both LEFT JOIN and RIGHT JOIN as follows-


But MySql also does not have a RIGHT JOIN syntax. According to MySql's outer join simplification, the right join is converted to the equivalent left join by switching the t1 and t2 in the FROM and ON clause in the query. Thus, the MySql Query Optimizer translates the original query into the following -


Now, there is no harm in writing the original query as is, but say if you have predicates like the WHERE clause, which is a before-join predicate or an AND predicate on the ON clause, which is a during-join predicate, then you might want to take a look at the devil; which is in details.

MySql query optimizer routinely checks the predicates if they are null-rejected. Null-Rejected Definition and Examples Now, if you have done the RIGHT JOIN, but with WHERE predicate on the column from t1, then you might be at a risk of running into a null-rejected scenario.

For example, THe following query -

WHERE t1.col1 = 'someValue'
WHERE t1.col1 = 'someValue'

gets translated to the following by the Query Optimizer-

WHERE t1.col1 = 'someValue'
WHERE t1.col1 = 'someValue'

So the order of tables has changed, but the predicate is still applied to t1, but t1 is now in the 'ON' clause. If t1.col1 is defined as NOT NULL column, then this query will be null-rejected.

Any outer-join (left, right, full) that is null-rejected is converted to an inner-join by MySql.

Thus the results you might be expecting might be completely different from what the MySql is returning. You might think its a bug with MySql's RIGHT JOIN, but thats not right. Its just how the MySql query-optimizer works. So the developer-in-charge has to pay attention to these nuances when he is constructing the query.

Get a timestamp in C in microseconds?

But this returns some nonsense value that if I get two timestamps, the second one can be smaller or bigger than the first (second one should always be bigger).

What makes you think that? The value is probably OK. It’s the same situation as with seconds and minutes – when you measure time in minutes and seconds, the number of seconds rolls over to zero when it gets to sixty.

To convert the returned value into a “linear” number you could multiply the number of seconds and add the microseconds. But if I count correctly, one year is about 1e6*60*60*24*360 µsec and that means you’ll need more than 32 bits to store the result:

$ perl -E '$_=1e6*60*60*24*360; say int log($_)/log(2)'

That’s probably one of the reasons to split the original returned value into two pieces.

Commenting out a set of lines in a shell script

You can use a 'here' document with no command to send it to.

echo "Say Something"
    your comment 1
    comment 2
echo "Do something else"

Wikipedia Reference

How do I autoindent in Netbeans?

Ctrl+Shift+F will do a format of all the code in the page.

How to use a Java8 lambda to sort a stream in reverse order?

Instead of all these complications, this simple step should do the trick for reverse sorting using Lambda .sorted(Comparator.reverseOrder())

.filter(file -> isNameLikeBaseLine(file, baseLineFile.getName()))
.forEach(item -> item.delete());

Check if cookies are enabled

You cannot in the same page's loading set and check if cookies is set you must perform reload page:

  • PHP run at Server;
  • cookies at client.
  • cookies sent to server only during loading of a page.
  • Just created cookies have not been sent to server yet and will be sent only at next load of the page.

JavaScript Uncaught ReferenceError: jQuery is not defined; Uncaught ReferenceError: $ is not defined

You did not include jquery library. In jsfiddle its already there. Just include this line in your head section.

 <script src="">

How to install Visual C++ Build tools?

I had the same issue too, the problem is exacerbated with the download link now only working for Visual Studio 2017, and installing the package from the download link did nothing for VS2015, although it took up 5gB of space.

I looked everywhere on how to do it with the Nu Get package manager and I couldn't find the solution.

It turns out it's even simpler than that, all you have to do is right-click the project or solution in the Solution Explorer from within Visual Studio, and click "Install Missing Components"

Display a jpg image on a JPanel

I'd probably use an ImageIcon and set it on a JLabel which I'd add to the JPanel.

Here's Sun's docs on the subject matter.

Execute ssh with password authentication via windows command prompt

What about this expect script?

#!/usr/bin/expect -f
spawn ssh root@myhost
expect -exact "root@myhost's password: "
send -- "mypassword\r"

Formula to determine brightness of RGB color

I wonder how those rgb coefficients were determined. I did an experiment myself and I ended up with the following:

Y = 0.267 R + 0.642 G + 0.091 B

Close but but obviously different than the long established ITU coefficients. I wonder if those coefficients could be different for each and every observer, because we all may have a different amount of cones and rods on the retina in our eyes, and especially the ratio between the different types of cones may differ.

For reference:

ITU BT.709:

Y = 0.2126 R + 0.7152 G + 0.0722 B

ITU BT.601:

Y = 0.299 R + 0.587 G + 0.114 B

I did the test by quickly moving a small gray bar on a bright red, bright green and bright blue background, and adjusting the gray until it blended in just as much as possible. I also repeated that test with other shades. I repeated the test on different displays, even one with a fixed gamma factor of 3.0, but it all looks the same to me. More over, the ITU coefficients literally are wrong for my eyes.

And yes, I presumably have a normal color vision.

CKEditor, Image Upload (filebrowserUploadUrl)

You can use this code

                // Replace the <textarea id="editor"> with a CKEditor
                // instance, using default configuration.

                CKEDITOR.config.filebrowserImageBrowseUrl = '/admin/laravel-filemanager?type=Files';
                CKEDITOR.config.filebrowserImageUploadUrl = '/admin/laravel-filemanager/upload?type=Images&_token=';
                CKEDITOR.config.filebrowserBrowseUrl = '/admin/laravel-filemanager?type=Files';
                CKEDITOR.config.filebrowserUploadUrl = '/admin/laravel-filemanager/upload?type=Files&_token=';

                CKEDITOR.replaceAll( 'editor');

Session 'app': Error Launching activity

All answers did not work for me.This error raised when I was trying to rename the app package.I have ended up creating a new project with the new package name and move my files to the new one.

CSS hexadecimal RGBA?

In Sass we can write:

background-color: rgba(#ff0000, 0.5);

as it was suggested in Hex representation of a color with alpha channel?

How to disable Hyper-V in command line?

I tried all of stack overflow and all didn't works. But this works for me:

  1. Open System Configuration
  2. Click Service tab
  3. Uncheck all of Hyper-V related

Reading HTTP headers in a Spring REST controller

I'm going to give you an example of how I read REST headers for my controllers. My controllers only accept application/json as a request type if I have data that needs to be read. I suspect that your problem is that you have an application/octet-stream that Spring doesn't know how to handle.

Normally my controllers look like this:

public class FooController {
    private DataService dataService;

    @RequestMapping(value="/foo/", method = RequestMethod.GET)
    public ResponseEntity<Data> getData(@RequestHeader String dataId){
        return ResponseEntity.newInstance(dataService.getData(dataId);

Now there is a lot of code doing stuff in the background here so I will break it down for you.

ResponseEntity is a custom object that every controller returns. It contains a static factory allowing the creation of new instances. My Data Service is a standard service class.

The magic happens behind the scenes, because you are working with JSON, you need to tell Spring to use Jackson to map HttpRequest objects so that it knows what you are dealing with.

You do this by specifying this inside your <mvc:annotation-driven> block of your config

        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <property name="objectMapper" ref="objectMapper" />

ObjectMapper is simply an extension of com.fasterxml.jackson.databind.ObjectMapper and is what Jackson uses to actually map your request from JSON into an object.

I suspect you are getting your exception because you haven't specified a mapper that can read an Octet-Stream into an object, or something that Spring can handle. If you are trying to do a file upload, that is something else entirely.

So my request that gets sent to my controller looks something like this simply has an extra header called dataId.

If you wanted to change that to a request parameter and use @RequestParam String dataId to read the ID out of the request your request would look similar to this:

contactId : {"fooId"} 

This request parameter can be as complex as you like. You can serialize an entire object into JSON, send it as a request parameter and Spring will serialize it (using Jackson) back into a Java Object ready for you to use.

Example In Controller:

@RequestMapping(value = "/penguin Details/", method = RequestMethod.GET)
public DataProcessingResponseDTO<Pengin> getPenguinDetailsFromList(
        @RequestParam DataProcessingRequestDTO jsonPenguinRequestDTO)

Request Sent:

jsonPengiunRequestDTO: {
    "draw": 1,
    "columns": [
            "data": {
                "_": "toAddress",
                "header": "toAddress"
            "name": "toAddress",
            "searchable": true,
            "orderable": true,
            "search": {
                "value": "",
                "regex": false
            "data": {
                "_": "fromAddress",
                "header": "fromAddress"
            "name": "fromAddress",
            "searchable": true,
            "orderable": true,
            "search": {
                "value": "",
                "regex": false
            "data": {
                "_": "customerCampaignId",
                "header": "customerCampaignId"
            "name": "customerCampaignId",
            "searchable": true,
            "orderable": true,
            "search": {
                "value": "",
                "regex": false
            "data": {
                "_": "penguinId",
                "header": "penguinId"
            "name": "penguinId",
            "searchable": false,
            "orderable": true,
            "search": {
                "value": "",
                "regex": false
            "data": {
                "_": "validpenguin",
                "header": "validpenguin"
            "name": "validpenguin",
            "searchable": true,
            "orderable": true,
            "search": {
                "value": "",
                "regex": false
            "data": {
                "_": "",
                "header": ""
            "name": "",
            "searchable": false,
            "orderable": false,
            "search": {
                "value": "",
                "regex": false
    "order": [
            "column": 0,
            "dir": "asc"
    "start": 0,
    "length": 10,
    "search": {
        "value": "",
        "regex": false
    "objectId": "30"

which gets automatically serialized back into an DataProcessingRequestDTO object before being given to the controller ready for me to use.

As you can see, this is quite powerful allowing you to serialize your data from JSON to an object without having to write a single line of code. You can do this for @RequestParam and @RequestBody which allows you to access JSON inside your parameters or request body respectively.

Now that you have a concrete example to go off, you shouldn't have any problems once you change your request type to application/json.

Difference between Git and GitHub

In simple:

Git - is local repository.

GitHub - is central repository.

Hope below image will help to understand: Git and GitHub Difference

Git and GitHub Difference more details

How to perform OR condition in django queryset?

Both options are already mentioned in the existing answers:

from django.db.models import Q
q1 = User.objects.filter(Q(income__gte=5000) | Q(income__isnull=True))


q2 = User.objects.filter(income__gte=5000) | User.objects.filter(income__isnull=True)

However, there seems to be some confusion regarding which one is to prefer.

The point is that they are identical on the SQL level, so feel free to pick whichever you like!

The Django ORM Cookbook talks in some detail about this, here is the relevant part:

queryset = User.objects.filter(
    ) | User.objects.filter(

leads to

In [5]: str(queryset.query)
Out[5]: 'SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login",
"auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name",
"auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff",
"auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user"
WHERE ("auth_user"."first_name"::text LIKE R% OR "auth_user"."last_name"::text LIKE D%)'


qs = User.objects.filter(Q(first_name__startswith='R') | Q(last_name__startswith='D'))

leads to

In [9]: str(qs.query)
Out[9]: 'SELECT "auth_user"."id", "auth_user"."password", "auth_user"."last_login",
 "auth_user"."is_superuser", "auth_user"."username", "auth_user"."first_name",
  "auth_user"."last_name", "auth_user"."email", "auth_user"."is_staff",
  "auth_user"."is_active", "auth_user"."date_joined" FROM "auth_user"
  WHERE ("auth_user"."first_name"::text LIKE R% OR "auth_user"."last_name"::text LIKE D%)'

source: django-orm-cookbook

How to add plus one (+1) to a SQL Server column in a SQL Query

You need both a value and a field to assign it to. The value is TableField + 1, so the assignment is:

SET TableField = TableField + 1

React: trigger onChange if input value is changing by state?

I know what you mean, you want to trigger handleChange by click button.

But modify state value will not trigger onChange event, because onChange event is a form element event.

Assigning default value while creating migration file

You would have to first create your migration for the model basics then you create another migration to modify your previous using the change_column ...

def change
    change_column :widgets, :colour, :string, default: 'red'

Combining multiple condition in single case statement in Sql Server

You can put the condition after the WHEN clause, like so:

    WHEN PAT_ENT.SCR_DT is not null and PAT_ENTRY.ELIGIBILITY is null THEN 'Favor'
    WHEN PAT_ENT.SCR_DT is not null and PAT_ENTRY.EL = 'No' THEN 'Error'
    WHEN PAT_ENTRY.EL = 'Yes' and ISNULL(DS.DES, 'OFF') = 'OFF' THEN 'Active'
    WHEN DS.DES = 'N' THEN 'Early Term'
    WHEN DS.DES = 'Y' THEN 'Complete'

Of course, the argument could be made that complex rules like this belong in your business logic layer, not in a stored procedure in the database...

UIBarButtonItem in navigation bar programmatically?

It's much easier with Swift 4 or Swift 4.2

inside your ViewDidLoad method, define your button and add it to the navigation bar.

override func viewDidLoad() {

    let logoutBarButtonItem = UIBarButtonItem(title: "Logout", style: .done, target: self, action: #selector(logoutUser))
    self.navigationItem.rightBarButtonItem  = logoutBarButtonItem


then you need to define the function that you mentioned inside action parameter as below

@objc func logoutUser(){

You need to add the @objc prefix as it's still making use of the legacy stuff (Objective C).

Are there such things as variables within an Excel formula?

Yes. But not directly.

Simpler way

  • You could post Vlookup() in one cell and use its address in where required. - This is perhaps the only direct way of using variables in Excel.


  • You could define Vlookup(reference)-10 as a wrapper function from within VBE Macros. Press Alt+f12 and use that function

How to show Page Loading div until the page has finished loading?

This will be in synchronisation with an api call, When the api call is triggered, the loader is shown. When the api call is succesful, the loader is removed. This can be used for either page load or during an api call.

    type: 'GET',
    url: url,
    async: true,
    dataType: 'json',
    beforeSend: function (xhr) {
      $( "<div class='loader' id='searching-loader'></div>").appendTo("#table-playlist-section");
      $("html, body").animate( { scrollTop: $(document).height() }, 100);
    success: function (jsonOptions) {


.loader {
  border: 2px solid #f3f3f3;
  border-radius: 50%;
  border-top: 2px solid #3498db;
  width: 30px;
  height: 30px;
  margin: auto;
  -webkit-animation: spin 2s linear infinite; /* Safari */
  animation: spin 2s linear infinite;
  margin-top: 35px;
  margin-bottom: -35px;

/* Safari */
@-webkit-keyframes spin {
  0% { -webkit-transform: rotate(0deg); }
  100% { -webkit-transform: rotate(360deg); }

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }

Generating PDF files with JavaScript

Another javascript library worth mentioning is pdfmake.

The browser support does not appear to be as strong as jsPDF, nor does there seem to be an option for shapes, but the options for formatting text are more advanced then the options currently available in jsPDF.

Filter df when values matches part of a string in pyspark

When filtering a DataFrame with string values, I find that the pyspark.sql.functions lower and upper come in handy, if your data could have column entries like "foo" and "Foo":

import pyspark.sql.functions as sql_fun
result = source_df.filter(sql_fun.lower(source_df.col_name).contains("foo"))

How can I see what I am about to push with git?

Just to add my two cents... I wanted to implement this when running jobs in a gitlab pipeline on a gitlab runner. The best way to do this was to use this script:

git diff --name-only $CI_COMMIT_BEFORE_SHA $CI_COMMIT_SHA

Also in my case I wanted to filter files by extension, to achieve this I used:

git diff --name-only $CI_COMMIT_BEFORE_SHA $CI_COMMIT_SHA '*.py'

After that you can for example forward this list somewhere else, a linter perhaps ;)

Hope this will help someone.

Best practice for using assert?

The English language word assert here is used in the sense of swear, affirm, avow. It doesn't mean "check" or "should be". It means that you as a coder are making a sworn statement here:

# I solemnly swear that here I will tell the truth, the whole truth, 
# and nothing but the truth, under pains and penalties of perjury, so help me FSM
assert answer == 42

If the code is correct, barring Single-event upsets, hardware failures and such, no assert will ever fail. That is why the behaviour of the program to an end user must not be affected. Especially, an assert cannot fail even under exceptional programmatic conditions. It just doesn't ever happen. If it happens, the programmer should be zapped for it.

How to install PHP mbstring on CentOS 6.2

If you have cPanel hosting you can use Easy Apache to do this through shell. These are the steps.

  1. Type the Easy Apache PathType the path for Easy Apache

    root@vps#### [~]# /scripts/easyapache

  2. Do not say yes to the "cPanel update available".
  3. Continue through the screens with defaults till you get to the "Exhaustive options list".
  4. Page down till you see the Mbstring extension listed and select it.
  5. Continue through the Steps and Save the Apache PHP build.

Apache and PHP will now rebuild to include the mbstring extension. Wait for the process to finish ~10 to 30 minutes. Once the process is finished you should see the Mbstring extension in the phpinfo now.

For more detailed steps see the article Installing the mbstring extension with Easy Apache

How can I debug git/git-shell related problems?


Git has a fairly complete set of traces embedded which you can use to debug your git problems.

To turn them on, you can define the following variables:

  • GIT_TRACE for general traces,
  • GIT_TRACE_PACK_ACCESS for tracing of packfile access,
  • GIT_TRACE_PACKET for packet-level tracing for network operations,
  • GIT_TRACE_PERFORMANCE for logging the performance data,
  • GIT_TRACE_SETUP for information about discovering the repository and environment it’s interacting with,
  • GIT_MERGE_VERBOSITY for debugging recursive merge strategy (values: 0-5),
  • GIT_CURL_VERBOSE for logging all curl messages (equivalent to curl -v),
  • GIT_TRACE_SHALLOW for debugging fetching/cloning of shallow repositories.

Possible values can include:

  • true, 1 or 2 to write to stderr,
  • an absolute path starting with / to trace output to the specified file.

For more details, see: Git Internals - Environment Variables


For SSH issues, try the following commands:

echo 'ssh -vvv "$*"' > ssh && chmod +x ssh
GIT_SSH="$PWD/ssh" git pull origin master

or use ssh to validate your credentials, e.g.

ssh -vvvT [email protected]

or over HTTPS port:

ssh -vvvT -p 443 [email protected]

Note: Reduce number of -v to reduce the verbosity level.


$ GIT_TRACE=1 git status
20:11:39.565701 git.c:350               trace: built-in: git 'status'

Counting objects: 143760, done.
$ head gc.log 
20:12:37.214410 trace.c:420             performance: 0.090286000 s: git command: 'git' 'pack-refs' '--all' '--prune'
20:12:37.378101 trace.c:420             performance: 0.156971000 s: git command: 'git' 'reflog' 'expire' '--all'

$ GIT_TRACE_PACKET=true git pull origin master
20:16:53.062183 pkt-line.c:80           packet:        fetch< 93eb028c6b2f8b1d694d1173a4ddf32b48e371ce HEAD\0multi_ack thin-pack side-band side-band-64k ofs-delta shallow no-progress include-tag multi_ack_detailed symref=HEAD:refs/heads/master agent=git/2:2.6.5~update-ref-initial-update-1494-g76b680d

unable to set private key file: './cert.pem' type PEM

After reading cURL documentation on the options you used, it looks like the private key of certificate is not in the same file. If it is in different file, you need to mention it using --key file and supply passphrase.

So, please make sure that either cert.pem has private key (along with the certificate) or supply it using --key option.

Also, this documentation mentions that Note that this option assumes a "certificate" file that is the private key and the private certificate concatenated!

How they are concatenated? It is quite easy. Put them one after another in the same file.

You can get more help on this here.

I believe this might help you.

Send HTTP GET request with header

You do it exactly as you showed with this line:

get.setHeader("Content-Type", "application/x-zip");

So your header is fine and the problem is some other input to the web service. You'll want to debug that on the server side.

Creating multiline strings in JavaScript


Ruby produce: "This\nIs\nA\nMultiline\nString\n" - below JS produce exact same string

text = `This


This is improvement to Lonnie Best answer because new-line characters in his answer are not exactly the same positions as in ruby output

How to ignore certain files in Git

Create a .gitignore in the directory where .git is. You can list files in it separated by a newline. You also can use wildcards:


Group by multiple field names in java 8

This is how I did grouping by multiple fields branchCode and prdId, Just posting it for someone in need

    import java.math.BigDecimal;
    import java.math.BigInteger;
    import java.util.ArrayList;
    import java.util.Iterator;
    import java.util.LinkedList;
    import java.util.List;
    import java.util.Map;

     * @author charudatta.joshi
    public class Product1 {

        public BigInteger branchCode;
        public BigInteger prdId;
        public String accountCode;
        public BigDecimal actualBalance;
        public BigDecimal sumActBal;
        public BigInteger countOfAccts;

        public Product1() {

        public Product1(BigInteger branchCode, BigInteger prdId, String accountCode, BigDecimal actualBalance) {
            this.branchCode = branchCode;
            this.prdId = prdId;
            this.accountCode = accountCode;
            this.actualBalance = actualBalance;

        public BigInteger getCountOfAccts() {
            return countOfAccts;

        public void setCountOfAccts(BigInteger countOfAccts) {
            this.countOfAccts = countOfAccts;

        public BigDecimal getSumActBal() {
            return sumActBal;

        public void setSumActBal(BigDecimal sumActBal) {
            this.sumActBal = sumActBal;

        public BigInteger getBranchCode() {
            return branchCode;

        public void setBranchCode(BigInteger branchCode) {
            this.branchCode = branchCode;

        public BigInteger getPrdId() {
            return prdId;

        public void setPrdId(BigInteger prdId) {
            this.prdId = prdId;

        public String getAccountCode() {
            return accountCode;

        public void setAccountCode(String accountCode) {
            this.accountCode = accountCode;

        public BigDecimal getActualBalance() {
            return actualBalance;

        public void setActualBalance(BigDecimal actualBalance) {
            this.actualBalance = actualBalance;

        public String toString() {
            return "Product{" + "branchCode:" + branchCode + ", prdId:" + prdId + ", accountCode:" + accountCode + ", actualBalance:" + actualBalance + ", sumActBal:" + sumActBal + ", countOfAccts:" + countOfAccts + '}';

        public static void main(String[] args) {
            List<Product1> al = new ArrayList<Product1>();
            al.add(new Product1(new BigInteger("01"), new BigInteger("11"), "001", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("01"), new BigInteger("11"), "002", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("01"), new BigInteger("12"), "003", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("01"), new BigInteger("12"), "004", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("01"), new BigInteger("12"), "005", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("01"), new BigInteger("13"), "006", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("11"), "007", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("11"), "008", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("12"), "009", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("12"), "010", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("12"), "011", new BigDecimal("10")));
            al.add(new Product1(new BigInteger("02"), new BigInteger("13"), "012", new BigDecimal("10")));
            //Map<BigInteger, Long> counting =, Collectors.counting()));
            // System.out.println(counting);

            //group by branch code
            Map<BigInteger, List<Product1>> groupByBrCd =, Collectors.toList()));
            System.out.println("\n\n\n" + groupByBrCd);

             Map<BigInteger, List<Product1>> groupByPrId = null;
              // Create a final List to show for output containing one element of each group
            List<Product> finalOutputList = new LinkedList<Product>();
            Product newPrd = null;
            // Iterate over resultant  Map Of List
            Iterator<BigInteger> brItr = groupByBrCd.keySet().iterator();
            Iterator<BigInteger> prdidItr = null;    

            BigInteger brCode = null;
            BigInteger prdId = null;

            Map<BigInteger, List<Product>> tempMap = null;
            List<Product1> accListPerBr = null;
            List<Product1> accListPerBrPerPrd = null;

            Product1 tempPrd = null;
            Double sum = null;
            while (brItr.hasNext()) {
                brCode =;
                //get  list per branch
                accListPerBr = groupByBrCd.get(brCode);

                // group by br wise product wise
      , Collectors.toList()));


                prdidItr = groupByPrId.keySet().iterator();
                    // get list per brcode+product code
                    newPrd = new Product();
                     // Extract zeroth element to put in Output List to represent this group
                    tempPrd = accListPerBrPerPrd.get(0);

                    //Set accCOunt by using size of list of our group
                    //Sum actual balance of our  of list of our group 
                    sum = -> o.getActualBalance() != null).mapToDouble(o -> o.getActualBalance().doubleValue()).sum();
                    // Add product element in final output list






Output is as below:

[Product{branchCode:1, prdId:11, accountCode:null, actualBalance:null, sumActBal:20.0, countOfAccts:2}, Product{branchCode:1, prdId:12, accountCode:null, actualBalance:null, sumActBal:30.0, countOfAccts:3}, Product{branchCode:1, prdId:13, accountCode:null, actualBalance:null, sumActBal:10.0, countOfAccts:1}, Product{branchCode:2, prdId:11, accountCode:null, actualBalance:null, sumActBal:20.0, countOfAccts:2}, Product{branchCode:2, prdId:12, accountCode:null, actualBalance:null, sumActBal:30.0, countOfAccts:3}, Product{branchCode:2, prdId:13, accountCode:null, actualBalance:null, sumActBal:10.0, countOfAccts:1}]

After Formatting it :

Product{branchCode:1, prdId:11, accountCode:null, actualBalance:null, sumActBal:20.0, countOfAccts:2}, 
Product{branchCode:1, prdId:12, accountCode:null, actualBalance:null, sumActBal:30.0, countOfAccts:3}, 
Product{branchCode:1, prdId:13, accountCode:null, actualBalance:null, sumActBal:10.0, countOfAccts:1}, 
Product{branchCode:2, prdId:11, accountCode:null, actualBalance:null, sumActBal:20.0, countOfAccts:2}, 
Product{branchCode:2, prdId:12, accountCode:null, actualBalance:null, sumActBal:30.0, countOfAccts:3}, 
Product{branchCode:2, prdId:13, accountCode:null, actualBalance:null, sumActBal:10.0, countOfAccts:1}

How to stretch children to fill cross-axis?

  • The children of a row-flexbox container automatically fill the container's vertical space.

  • Specify flex: 1; for a child if you want it to fill the remaining horizontal space:

.wrapper {_x000D_
  display: flex;_x000D_
  flex-direction: row;_x000D_
  align-items: stretch;_x000D_
  width: 100%;_x000D_
  height: 5em;_x000D_
  background: #ccc;_x000D_
.wrapper > .left_x000D_
  background: #fcc;_x000D_
.wrapper > .right_x000D_
  background: #ccf;_x000D_
  flex: 1; _x000D_
<div class="wrapper">_x000D_
  <div class="left">Left</div>_x000D_
  <div class="right">Right</div>_x000D_

  • Specify flex: 1; for both children if you want them to fill equal amounts of the horizontal space:

.wrapper {_x000D_
  display: flex;_x000D_
  flex-direction: row;_x000D_
  align-items: stretch;_x000D_
  width: 100%;_x000D_
  height: 5em;_x000D_
  background: #ccc;_x000D_
.wrapper > div _x000D_
  flex: 1; _x000D_
.wrapper > .left_x000D_
  background: #fcc;_x000D_
.wrapper > .right_x000D_
  background: #ccf;_x000D_
<div class="wrapper">_x000D_
  <div class="left">Left</div>_x000D_
  <div class="right">Right</div>_x000D_

Checking if a collection is empty in Java: which is the best method?

Use CollectionUtils.isEmpty(Collection coll)

Null-safe check if the specified collection is empty. Null returns true.

Parameters: coll - the collection to check, may be null

Returns: true if empty or null

C++: constructor initializer for arrays

class C
   static const int myARRAY[10];  // only declaration !!!


const int C::myARRAY[10]={0,1,2,3,4,5,6,7,8,9};  // here is definition

int main(void)
   C myObj;

Spring Could not Resolve placeholder

If you are using Spring 3.1 and above, you can use something like...

public class PropertiesWithJavaConfig {

public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
  return new PropertySourcesPlaceholderConfigurer();

You can also go by the xml configuration like...

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns=""

  <context:property-placeholder location="" />


In earlier versions.

jQuery datepicker set selected date, on the fly

This is a old thread but I just want to give some information how I have used. If you want to set today date you can simply apply it like below.

 $("#datepickerid").datepicker("setDate", "0");

If you want to set some days before/after the current date then use the symbol -/+ symbol of how many days you want like below.

 $("#datepickerid").datepicker("setDate", "-7");
 $("#datepickerid").datepicker("setDate", "+5");

Regular expression for validating names and surnames?

This one worked perfectly for me in JavaScript: ^[a-zA-Z]+[\s|-]?[a-zA-Z]+[\s|-]?[a-zA-Z]+$

Here is the method:

function isValidName(name) {
    var found =^[a-zA-Z]+[\s|-]?[a-zA-Z]+[\s|-]?[a-zA-Z]+$/);
    return found > -1;

android TextView: setting the background color dynamically doesn't work

I had a similar issue where I was creating a numeric color without considering the leading alpha channel. ie. mytext.setTextColor(0xFF0000) (thinking this would be red ). While this is a red color it is also 100% transparent as it = 0x00FF0000; The correct 100% opaque value is 0xFFFF0000 or mytext.setTextcolor(0xFFFF0000).

Working copy XXX locked and cleanup failed in SVN

The easiest way to do this is show hidden folders and then open the .SVN folder. You should see a zero KB file named "lock" deleting this will fix the problem

Drop data frame columns by name

Out of interest, this flags up one of R's weird multiple syntax inconsistencies. For example given a two-column data frame:

df <- data.frame(x=1, y=2)

This gives a data frame

subset(df, select=-y)

but this gives a vector


This is all explained in ?[ but it's not exactly expected behaviour. Well at least not to me...

Can a table row expand and close?

To answer your question, no. That would be possible with div though. THe only question is would cause a hazzle if the functionality were done with div rather than tables.

Virtualhost For Wildcard Subdomain and Static Subdomain

This also works for https needed a solution to making project directories this was it. because chrome doesn't like non ssl anymore used free ssl. Notice: My Web Server is Wamp64 on Windows 10 so I wouldn't use this config because of variables unless your using wamp.

<VirtualHost *:443>
ServerAdmin [email protected]
ServerAlias *

SSLEngine On
SSLCertificateFile "conf/key/certificatecom.crt"
SSLCertificateKeyFile "conf/key/privatecom.key"

VirtualDocumentRoot "${INSTALL_DIR}/www/subdomains/%1/"

DocumentRoot "${INSTALL_DIR}/www/subdomains"
<Directory "${INSTALL_DIR}/www/subdomains/">
    Options +Indexes +Includes +FollowSymLinks +MultiViews
AllowOverride All
Require all granted

How can I conditionally require form inputs with AngularJS?

For Angular 2

<input [(ngModel)]='email' [required]='!phone' />
<input [(ngModel)]='phone' [required]='!email' /> 

Display image as grayscale using matplotlib

Try to use a grayscale colormap?

E.g. something like


For a list of colormaps, see

What does operator "dot" (.) mean?

There is a whole page in the MATLAB documentation dedicated to this topic: Array vs. Matrix Operations. The gist of it is below:

MATLAB® has two different types of arithmetic operations: array operations and matrix operations. You can use these arithmetic operations to perform numeric computations, for example, adding two numbers, raising the elements of an array to a given power, or multiplying two matrices.

Matrix operations follow the rules of linear algebra. By contrast, array operations execute element by element operations and support multidimensional arrays. The period character (.) distinguishes the array operations from the matrix operations. However, since the matrix and array operations are the same for addition and subtraction, the character pairs .+ and .- are unnecessary.

A TypeScript GUID class?

I found this

here is the Guid version they have in case the link does not work later.

module System {
    export class Guid {
        constructor (public guid: string) {
            this._guid = guid;

        private _guid: string;

        public ToString(): string {
            return this.guid;

        // Static member
        static MakeNew(): Guid {
            var result: string;
            var i: string;
            var j: number;

            result = "";
            for (j = 0; j < 32; j++) {
                if (j == 8 || j == 12 || j == 16 || j == 20)
                    result = result + '-';
                i = Math.floor(Math.random() * 16).toString(16).toUpperCase();
                result = result + i;
            return new Guid(result);

Differences between arm64 and aarch64

AArch64 is the 64-bit state introduced in the Armv8-A architecture ( The 32-bit state which is backwards compatible with Armv7-A and previous 32-bit Arm architectures is referred to as AArch32. Therefore the GNU triplet for the 64-bit ISA is aarch64. The Linux kernel community chose to call their port of the kernel to this architecture arm64 rather than aarch64, so that's where some of the arm64 usage comes from.

As far as I know the Apple backend for aarch64 was called arm64 whereas the LLVM community-developed backend was called aarch64 (as it is the canonical name for the 64-bit ISA) and later the two were merged and the backend now is called aarch64.

So AArch64 and ARM64 refer to the same thing.

What is the difference between json.dump() and json.dumps() in python?

One notable difference in Python 2 is that if you're using ensure_ascii=False, dump will properly write UTF-8 encoded data into the file (unless you used 8-bit strings with extended characters that are not UTF-8):

dumps on the other hand, with ensure_ascii=False can produce a str or unicode just depending on what types you used for strings:

Serialize obj to a JSON formatted str using this conversion table. If ensure_ascii is False, the result may contain non-ASCII characters and the return value may be a unicode instance.

(emphasis mine). Note that it may still be a str instance as well.

Thus you cannot use its return value to save the structure into file without checking which format was returned and possibly playing with unicode.encode.

This of course is not valid concern in Python 3 any more, since there is no more this 8-bit/Unicode confusion.

As for load vs loads, load considers the whole file to be one JSON document, so you cannot use it to read multiple newline limited JSON documents from a single file.

PL/SQL ORA-01422: exact fetch returns more than requested number of rows

A SELECT INTO statement will throw an error if it returns anything other than 1 row. If it returns 0 rows, you'll get a no_data_found exception. If it returns more than 1 row, you'll get a too_many_rows exception. Unless you know that there will always be exactly 1 employee with a salary greater than 3000, you do not want a SELECT INTO statement here.

Most likely, you want to use a cursor to iterate over (potentially) multiple rows of data (I'm also assuming that you intended to do a proper join between the two tables rather than doing a Cartesian product so I'm assuming that there is a departmentID column in both tables)

                FROM EMPLOYEE, 
               WHERE employee.departmentID = department.departmentID
                 AND EMPLOYEE.SALARY > 3000)
    DBMS_OUTPUT.PUT_LINE ('Employee Nnumber: ' || rec.EMPID);
    DBMS_OUTPUT.PUT_LINE ('---------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Name: ' || rec.ENAME);
    DBMS_OUTPUT.PUT_LINE ('---------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Designation: ' || rec.DESIGNATION);
    DBMS_OUTPUT.PUT_LINE ('----------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Salary: ' || rec.SALARY);
    DBMS_OUTPUT.PUT_LINE ('----------------------------------------------------');
    DBMS_OUTPUT.PUT_LINE ('Employee Department: ' || rec.DEPT_NAME);

I'm assuming that you are just learning PL/SQL as well. In real code, you'd never use dbms_output like this and would not depend on anyone seeing data that you write to the dbms_output buffer.

async await return Task

Adding the async keyword is just syntactic sugar to simplify the creation of a state machine. In essence, the compiler takes your code;

public async Task MethodName()
     return null;

And turns it into;

public Task MethodName()
     return Task.FromResult<object>(null);

If your code has any await keywords, the compiler must take your method and turn it into a class to represent the state machine required to execute it. At each await keyword, the state of variables and the stack will be preserved in the fields of the class, the class will add itself as a completion hook to the task you are waiting on, then return.

When that task completes, your task will be executed again. So some extra code is added to the top of the method to restore the state of variables and jump into the next slab of your code.

See What does async & await generate? for a gory example.

This process has a lot in common with the way the compiler handles iterator methods with yield statements.

Pass a PHP string to a JavaScript variable (and escape newlines)

The paranoid version: Escaping every single character.

function javascript_escape($str) {
  $new_str = '';

  $str_len = strlen($str);
  for($i = 0; $i < $str_len; $i++) {
    $new_str .= '\\x' . sprintf('%02x', ord(substr($str, $i, 1)));

  return $new_str;

EDIT: The reason why json_encode() may not be appropriate is that sometimes, you need to prevent " to be generated, e.g.

<div onclick="alert(???)" />

How can I work with command line on synology?

I use GateOne from the synocommunity.

Go into settings in Package Center and add as a package source. Then you should be able to add it easily via Package Center.

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

Add .eslintrc in the project root.

  "globals": {
    "document": true,
    "foo": true,
    "window": true

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

Please follow those steps.

Bundle your js:

if you have in project root then run

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

if you have index.js in project root then run

react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/ --assets-dest android/app/src/main/res

Create debug apk:

cd android/
./gradlew assembleDebug

Then You can find your apk here:

cd app/build/outputs/apk/

Unable to find the wrapper "https" - did you forget to enable it when you configured PHP?

In my case, the issue was due to WAMP using a different php.ini for CLI than Apache, so your settings made through the WAMP menu don't apply to CLI. Just modify the CLI php.ini and it works.

What version of Java is running in Eclipse?

Under the help menu, there should be a menu item labeled "About Eclipse" I can't say with absolute precision because I'm using STS which is the same thing but my label is different.

In the dialog box that opens after you click the relevant about menu item there should be an installation details button in the lower left hand corner.

The version of Java that you're running Eclipse against ought to be in "System properties:" under the "Configuration" tab.

postgresql duplicate key violates unique constraint

I have similar problem but I solved it by removing all the foreign key in my Postgresql

Warning: Attempt to present * on * whose view is not in the window hierarchy - swift

Swift 4

func topMostController() -> UIViewController {
    var topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!
    while (topController.presentedViewController != nil) {
        topController = topController.presentedViewController!
    return topController

How to align a div inside td element using CSS class

I cannot help you much without a small (possibly reduced) snippit of the problem. If the problem is what I think it is then it's because a div by default takes up 100% width, and as such cannot be aligned.

What you may be after is to align the inline elements inside the div (such as text) with text-align:center; otherwise you may consider setting the div to display:inline-block;

If you do go down the inline-block route then you may have to consider my favorite IE hack.

zoom:1; //IE only
*display:inline; //IE only

Happy Coding :)

python getoutput() equivalent in subprocess

To catch errors with subprocess.check_output(), you can use CalledProcessError. If you want to use the output as string, decode it from the bytecode.

# \return String of the output, stripped from whitespace at right side; or None on failure.
def runls():
    import subprocess
        byteOutput = subprocess.check_output(['ls', '-a'], timeout=2)
        return byteOutput.decode('UTF-8').rstrip()
    except subprocess.CalledProcessError as e:
        print("Error in ls -a:\n", e.output)
        return None

Encode/Decode URLs in C++

[Necromancer mode on]
Stumbled upon this question when was looking for fast, modern, platform independent and elegant solution. Didnt like any of above, cpp-netlib would be the winner but it has horrific memory vulnerability in "decoded" function. So I came up with boost's spirit qi/karma solution.

namespace bsq = boost::spirit::qi;
namespace bk = boost::spirit::karma;
bsq::int_parser<unsigned char, 16, 2, 2> hex_byte;
template <typename InputIterator>
struct unescaped_string
    : bsq::grammar<InputIterator, std::string(char const *)> {
  unescaped_string() : unescaped_string::base_type(unesc_str) {
    unesc_char.add("+", ' ');

    unesc_str = *(unesc_char | "%" >> hex_byte | bsq::char_);

  bsq::rule<InputIterator, std::string(char const *)> unesc_str;
  bsq::symbols<char const, char const> unesc_char;

template <typename OutputIterator>
struct escaped_string : bk::grammar<OutputIterator, std::string(char const *)> {
  escaped_string() : escaped_string::base_type(esc_str) {

    esc_str = *(bk::char_("a-zA-Z0-9_.~-") | "%" << bk::right_align(2,0)[bk::hex]);
  bk::rule<OutputIterator, std::string(char const *)> esc_str;

The usage of above as following:

std::string unescape(const std::string &input) {
  std::string retVal;
  typedef std::string::const_iterator iterator_type;

  char const *start = "";
  iterator_type beg = input.begin();
  iterator_type end = input.end();
  unescaped_string<iterator_type> p;

  if (!bsq::parse(beg, end, p(start), retVal))
    retVal = input;
  return retVal;

std::string escape(const std::string &input) {
  typedef std::back_insert_iterator<std::string> sink_type;
  std::string retVal;
  retVal.reserve(input.size() * 3);
  sink_type sink(retVal);
  char const *start = "";

  escaped_string<sink_type> g;
  if (!bk::generate(sink, g(start), input))
    retVal = input;
  return retVal;

[Necromancer mode off]

EDIT01: fixed the zero padding stuff - special thanks to Hartmut Kaiser
EDIT02: Live on CoLiRu

React ignores 'for' attribute of the label element

both for and class are reserved words in JavaScript this is why when it comes to HTML attributes in JSX you need to use something else, React team decided to use htmlFor and className respectively

Shell Script: How to write a string to file and to stdout on console?

Use the tee command:

echo "hello" | tee logfile.txt

PHP strtotime +1 month adding an extra month

today is 29th of January, +1 month means 29th of Fabruary, but because February consists of 28 days this year, it overlaps to the next day which is March 1st

instead try

strtotime('next month')

LDAP filter for blank (empty) attribute

Search for a null value by using \00

For example:

ldapsearch -D cn=admin -w pass -s sub -b ou=users,dc=acme 'manager=\00' uid manager

Make sure if you use the null value on the command line to use quotes around it to prevent the OS shell from sending a null character to LDAP. For example, this won't work:

 ldapsearch -D cn=admin -w pass -s sub -b ou=users,dc=acme manager=\00 uid manager

There are various sites that reference this, along with other special characters. Example:

How to reload current page in ReactJS?

Since React eventually boils down to plain old JavaScript, you can really place it anywhere! For instance, you could place it on a componentDidMount() in a React class.

For you edit, you may want to try something like this:

class Component extends React.Component {
  constructor(props) {
    this.onAddBucket = this.onAddBucket.bind(this);
  componentWillMount() {
      buckets: {},
  componentDidMount() {
  onAddBucket() {
    let self = this;
    let getToken = localStorage.getItem('myToken');
    var apiBaseUrl = "...";
    let input = {
      "name" :  this.state.fields["bucket_name"]
    axios.defaults.headers.common['Authorization'] = getToken;'...',input)
    .then(function (response) {
      if ( == 200) {
          buckets: this.state.buckets.concat(,
      } else {
    .catch(function (error) {
  render() {
    return (

refresh both the External data source and pivot tables together within a time schedule

I think there is a simpler way to make excel wait till the refresh is done, without having to set the Background Query property to False. Why mess with people's preferences right?

Excel 2010 (and later) has this method called CalculateUntilAsyncQueriesDone and all you have to do it call it after you have called the RefreshAll method. Excel will wait till the calculation is complete.


I usually put these things together to do a master full calculate without interruption, before sending my models to others. Something like this:


Create a tag in a GitHub repository

In case you want to tag a specific commit like i do

Here's a command to do that :-


git tag -a v1.0 7cceb02 -m "Your message here"

Where 7cceb02 is the beginning part of the commit id.

You can then push the tag using git push origin v1.0.

You can do git log to show all the commit id's in your current branch.

How can I set multiple CSS styles in JavaScript?

You can have individual classes in your css files and then assign the classname to your element

or you can loop through properties of styles as -

var css = { "font-size": "12px", "left": "200px", "top": "100px" };

for(var prop in css) {
  document.getElementById("myId").style[prop] = css[prop];

CURL to pass SSL certifcate and password

Addition to previous answer make sure that your curl installation supports https.
You can use curl --version to get information about supported protocols.

If your curl supports https follow the previous answer.

curl --cert certificate_path:password

If it does not support https, you need to install a cURL version that supports https.

How do I round a double to two decimal places in Java?

You can't 'round a double to [any number of] decimal places', because doubles don't have decimal places. You can convert a double to a base-10 String with N decimal places, because base-10 does have decimal places, but when you convert it back you are back in double-land, with binary fractional places.

Restoring MySQL database from physical files

Yes it is! Just add them to your database-folder ( depending on the OS ) and run a command such as "MySQL Fix Permissions". This re-stored the database. See too it that the correct permissions are set on the files aswell.


I don't know why

cfg_name_unique NOT LIKE '%categories%' 

still returns those two values, but maybe exclude them explicit:

    FROM developer_configurations_cms

    WHERE developer_configurations_cms.cat_id = '1'
    AND developer_configurations_cms.cfg_variables LIKE '%parent_id=2%'
    AND developer_configurations_cms.cfg_name_unique NOT LIKE '%categories%'
    AND developer_configurations_cms.cfg_name_unique NOT IN ('categories_posts', 'categories_news')

Key Listeners in python?

Although I like using the keyboard module to capture keyboard events, I don't like its record() function because it returns an array like [KeyboardEvent("A"), KeyboardEvent("~")], which I find kind of hard to read. So, to record keyboard events, I like to use the keyboard module and the threading module simultaneously, like this:

import keyboard
import string
from threading import *

# I can't find a complete list of keyboard keys, so this will have to do:
keys = list(string.ascii_lowercase)
Optional code(extra keys):

def listen(key):
    while True:
        print("[+] Pressed",key)
threads = [Thread(target=listen, kwargs={"key":key}) for key in keys]
for thread in threads:

pull out p-values and r-squared from a linear regression

Another option is to use the cor.test function, instead of lm:

> x <- c(44.4, 45.9, 41.9, 53.3, 44.7, 44.1, 50.7, 45.2, 60.1)
> y <- c( 2.6,  3.1,  2.5,  5.0,  3.6,  4.0,  5.2,  2.8,  3.8)

> mycor = cor.test(x,y)
> mylm = lm(x~y)

# r and rsquared:
> cor.test(x,y)$estimate ** 2
> summary(lm(x~y))$r.squared
[1] 0.3262484

# P.value 

> lmp(lm(x~y))  # Using the lmp function defined in Chase's answer
[1] 0.1081731
> cor.test(x,y)$p.value
[1] 0.1081731

Execute specified function every X seconds

The most beginner-friendly solution is:

Drag a Timer from the Toolbox, give it a Name, set your desired Interval, and set "Enabled" to True. Then double-click the Timer and Visual Studio (or whatever you are using) will write the following code for you:

private void wait_Tick(object sender, EventArgs e)
    refreshText(); // Add the method you want to call here.

No need to worry about pasting it into the wrong code block or something like that.

How to select records without duplicate on just one field in SQL?

Having Clause is the easiest way to find duplicate entry in Oracle and using rowid we can remove duplicate data..

DELETE FROM products WHERE rowid IN (
  SELECT itemcode, (rowid) sl FROM products WHERE itemcode IN (
  SELECT itemcode FROM products GROUP BY itemcode HAVING COUNT(itemcode)>1
)) GROUP BY itemcode);

Is there a way to automatically generate getters and setters in Eclipse?

Press Alt+Shift+S+R... and then only select which all fields you have to generate Getters or Setters or both

Copy Image from Remote Server Over HTTP

make folder and name it foe example download open note pad and insert this code

only change to your file and save it to m.php for example

chamod the php file to 666 and the folder download to 777

define('BUFSIZ', 4095);
$url = '';
$rfile = fopen($url, 'r');
$lfile = fopen(basename($url), 'w');
fwrite($lfile, fread($rfile, BUFSIZ), BUFSIZ);

finally from your browser enter to these URL

you will see in download folder the file download from other server


Triangle Draw Method

You can use Processing library:

There is a method called triangle():


show icon in actionbar/toolbar with AppCompat-v7 21

if you want to set the home or back icon (not logo or static icon) so you can use

 getSupportActionBar().setHomeAsUpIndicator( getResources().getDrawable(R.drawable.home) );

How to build a Debian/Ubuntu package from source?

If you want a quick and dirty way of installing the build dependencies, use:

apt-get build-dep

This installs the dependencies. You need sources lines in your sources.list for this:

deb-src squeeze-updates main contrib non-free

If you are backporting packages from testing to stable, please be advised that the dependencies might have changed. The command apt-get build-deb installs dependencies for the source packages in your current repository.

But of course, dpkg-buildpackage -us -uc will show you any uninstalled dependencies.

If you want to compile more often, use cowbuilder.

apt-get install cowbuilder

Then create a build-area:

sudo DIST=squeeze ARCH=amd64 cowbuilder --create

Then compile a source package:

apt-get source cowsay

# do your magic editing
dpkg-source -b cowsay-3.03+dfsg1              # build the new source packages
cowbuilder --build cowsay_3.03+dfsg1-2.dsc    # build the packages from source

Watch where cowbuilder puts the resulting package.

Good luck!

dispatch_after - GCD in Swift?

I always prefer to use extension instead of free functions.

Swift 4

public extension DispatchQueue {

  private class func delay(delay: TimeInterval, closure: @escaping () -> Void) {
    let when = + delay
    DispatchQueue.main.asyncAfter(deadline: when, execute: closure)

  class func performAction(after seconds: TimeInterval, callBack: @escaping (() -> Void) ) {
    DispatchQueue.delay(delay: seconds) {


Use as follow.

DispatchQueue.performAction(after: 0.3) {
  // Code Here

What is InputStream & Output Stream? Why and when do we use them?

An output stream is generally related to some data destination like a file or a network etc.In java output stream is a destination where data is eventually written and it ends


class PPrint {
    static PPrintStream oout = new PPrintStream();

class PPrintStream {
    void print(String str) { 

class outputstreamDemo {
    public static void main(String args[]) {
        System.out.println("hello world");
        System.out.prinln("this is output stream demo");

Currency format for display

You can use string.Format("{0:c}", value).

See also here:

How to drop column with constraint?

First you should drop the problematic DEFAULT constraint, after that you can drop the column

alter table tbloffers drop constraint [ConstraintName]

alter table tbloffers drop column checkin

But the error may appear from other reasons - for example the user defined function or view with SCHEMABINDING option set for them.

UPD: Completely automated dropping of constraints script:

    SELECT TOP 1 @sql = N'alter table tbloffers drop constraint ['+dc.NAME+N']'
    from sys.default_constraints dc
    JOIN sys.columns c
        ON c.default_object_id = dc.object_id
        dc.parent_object_id = OBJECT_ID('tbloffers')
    AND = N'checkin'
    EXEC (@sql)

Rewrite all requests to index.php with nginx

1 unless file exists will rewrite to index.php

Add the following to your location ~ \.php$

try_files = $uri @missing;

this will first try to serve the file and if it's not found it will move to the @missing part. so also add the following to your config (outside the location block), this will redirect to your index page

location @missing {
    rewrite ^ $scheme://$host/index.php permanent;

2 on the urls you never see the file extension (.php)

to remove the php extension read the following:

and the example configuration from the link:

location / {
    set $page_to_view "/index.php";
    try_files $uri $uri/ @rewrites;
    root   /var/www/site;
    index  index.php index.html index.htm;

location ~ \.php$ {
    include /etc/nginx/fastcgi_params;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME /var/www/site$page_to_view;

# rewrites
location @rewrites {
    if ($uri ~* ^/([a-z]+)$) {
        set $page_to_view "/$1.php";
        rewrite ^/([a-z]+)$ /$1.php last;

Easy way to pull latest of all git submodules

The following worked for me on Windows.

git submodule init
git submodule update

React Hooks useState() with Object

function App() {

  const [todos, setTodos] = useState([
    { id: 1, title: "Selectus aut autem", completed: false },
    { id: 2, title: "Luis ut nam facilis et officia qui", completed: false },
    { id: 3, title: "Fugiat veniam minus", completed: false },
    { id: 4, title: "Aet porro tempora", completed: true },
    { id: 5, title: "Laboriosam mollitia et enim quasi", completed: false }

  const changeInput = (e) => { => === parseInt( && (items.completed =;
 setTodos([...todos], todos);}
  return (
    <div className="container">
      { => {
        return (
          <div key={}>
<input type="checkbox" 
checked={items.completed} />&nbsp; {items.title}</label>

Error 'LINK : fatal error LNK1123: failure during conversion to COFF: file invalid or corrupt' after installing Visual Studio 2012 Release Preview

As of January 2014, for some reasons I got installed .NET Framework 4.5.1, I don't know if due to a third party software installation or to an automatic update.

On January 29th, I got installed one component and I started receiving the

LINK : fatal error LNK1123: failure during conversion to COFF: file invalid or corrupt 

message. At that time, I solved by avoiding the incremental link.

On Jan. 31st, I got installed another component of .NET Framework 4.5.1 and the incremental link trick did not work anymore. I then installed the Visual Studio 2010 SP1, but afterwards the problem became:

Error   6   error LNK1104: cannot open file 'msvcrtd.lib'. 

I think the SP1 messed up my Visual Studio 2010 installation.

So I uninstalled .NET Framework 4.5.1, installed .NET Framework 4.0 and uninstalled and then reinstalled Visual Studio 2010. That worked for me.

Reading/parsing Excel (xls) files with Python

For xlsx I like the solution posted earlier as I uses modules from the standard library only.

def xlsx(fname):
    import zipfile
    from xml.etree.ElementTree import iterparse
    z = zipfile.ZipFile(fname)
    strings = [el.text for e, el in iterparse('xl/sharedStrings.xml')) if el.tag.endswith('}t')]
    rows = []
    row = {}
    value = ''
    for e, el in iterparse('xl/worksheets/sheet1.xml')):
        if el.tag.endswith('}v'):  # Example: <v>84</v>                            
            value = el.text
        if el.tag.endswith('}c'):  # Example: <c r="A3" t="s"><v>84</v></c>                                 
            if el.attrib.get('t') == 's':
                value = strings[int(value)]
            letter = el.attrib['r']  # Example: AZ22                         
            while letter[-1].isdigit():
                letter = letter[:-1]
            row[letter] = value
            value = ''
        if el.tag.endswith('}row'):
            row = {}
    return rows

Improvements added are fetching content by sheet name, using re to get the column and checking if sharedstrings are used.

def xlsx(fname,sheet):
    import zipfile
    from xml.etree.ElementTree import iterparse
    import re
    z = zipfile.ZipFile(fname)
    if 'xl/sharedStrings.xml' in z.namelist():
        # Get shared strings
        strings = [element.text for event, element
                   in iterparse('xl/sharedStrings.xml')) 
                   if element.tag.endswith('}t')]
    sheetdict = { element.attrib['name']:element.attrib['sheetId'] for event,element in iterparse('xl/workbook.xml'))
                                      if element.tag.endswith('}sheet') }
    rows = []
    row = {}
    value = ''

    if sheet in sheets:
    sheetfile = 'xl/worksheets/sheet'+sheets[sheet]+'.xml'
    for event, element in iterparse(
        # get value or index to shared strings
        if element.tag.endswith('}v') or element.tag.endswith('}t'):
            value = element.text
        # If value is a shared string, use value as an index
        if element.tag.endswith('}c'):
            if element.attrib.get('t') == 's':
                value = strings[int(value)]
            # split the row/col information so that the row leter(s) can be separate
            letter = re.sub('\d','',element.attrib['r'])
            row[letter] = value
            value = ''
        if element.tag.endswith('}row'):
            row = {}

    return rows

Executing an EXE file using a PowerShell script

& "C:\Program Files\Automated QA\TestExecute 8\Bin\TestExecute.exe" C:\temp\TestProject1\TestProject1.pjs /run /exit /SilentMode


[System.Diagnostics.Process]::Start("C:\Program Files\Automated QA\TestExecute 8\Bin\TestExecute.exe", "C:\temp\TestProject1\TestProject1.pjs /run /exit /SilentMode")

UPDATE: sorry I missed "(I invoked the command using the "&" operator)" sentence. I had this problem when I was evaluating the path dynamically. Try Invoke-Expression construction:

Invoke-Expression "& `"C:\Program Files\Automated QA\TestExecute 8\Bin\TestExecute.exe`" C:\temp\TestProject1\TestProject1.pjs /run /exit /SilentMode"

Installing a pip package from within a Jupyter Notebook not working

! pip install --user <package>

The ! tells the notebook to execute the cell as a shell command.

Google Play on Android 4.0 emulator

Have you ever tried Genymotion? I've read about it last week and it is great. They have several Android Images that you run (with their own software). The images are INCREDIBLY fast and they have Google Play installed on them. Check it out if it is the kind of thing that you need.

Favicon not showing up in Google Chrome

Upload your favicon.ico to the root directory of your website and that should work with Chrome. Some browsers disregard the meta tag and just use /favicon.ico

Go figure?.....

how to get the first and last days of a given month

## Get Current Month's First Date And Last Date

echo "Today Date: ". $query_date = date('d-m-Y');
echo "<br> First day of the month: ". date('01-m-Y', strtotime($query_date));
echo "<br> Last day of the month: ". date('t-m-Y', strtotime($query_date));

Reading RFID with Android phones

NFC enabled phones can ONLY read NFC and passive high frequency RFID (HF-RFID). These must be read at an extremely close range, typically a few centimeters. For longer range or any other type of RFID/active RFID, you must use an external reader for handling them with mobile devices.

You can get some decent readers from a lot of manufacturers by simply searching on google. There are a lot of plug in ones for all device types.

I deal a lot with HID readers capable of close proximity scans of HID enabled ID cards as well as NFC from smart phones and smart cards. I use SerialIO badge readers that I load a decryption profile onto that allows our secure company cards to be read and utilized by an application I built. They are great for large scale reliable bluetooth scanning. Because they are bluetooth, they work for PC/Android/iOS/Linux. The only problem is, HID readers are very expensive and are meant for enterprise use. Ours cost about $400 each, but again, they read HID, SmartCards, NFC, and RFID.

If this is a personal project, I suggest just using the phone and purchasing some HF-RFID tags. The tag manufacturer should have an SDK for you to use to connect to and manage the tags. You can also just use androids NFC docs to get started Most android phones from the last 8 years have NFC, only iPhone 6 and newer apple phones have NFC, but only iOS 11 and newer will work for what you want to do.

Running CMake on Windows

There is a vcvars32.bat in your Visual Studio installation directory. You can add call cmd.exe at the end of that batch program and launch it. From that shell you can use CMake or cmake-gui and cl.exe would be known to CMake.

node.js Error: connect ECONNREFUSED; response from server

If you have stopped the mongod.exe service from the task manager, you need to restart the service. In my case I stopped the service from task manager and on restart it doesn't automatically started.

SVN remains in conflict?

Ok here's how to fix it:

svn remove --force filename
svn resolve --accept=working  filename
svn commit

more details are at:

Referring to a Column Alias in a WHERE Clause

   logcount, logUserID, maxlogtm,
   DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
FROM statslogsummary
WHERE ( DATEDIFF(day, maxlogtm, GETDATE() > 120)

Normally you can't refer to field aliases in the WHERE clause. (Think of it as the entire SELECT including aliases, is applied after the WHERE clause.)

But, as mentioned in other answers, you can force SQL to treat SELECT to be handled before the WHERE clause. This is usually done with parenthesis to force logical order of operation or with a Common Table Expression (CTE):


      logcount, logUserID, maxlogtm,
      DATEDIFF(day, maxlogtm, GETDATE()) AS daysdiff
   FROM statslogsummary   
) as innerTable
WHERE daysdiff > 120

Or see Adam's answer for a CTE version of the same.

using favicon with css

You can't set a favicon from CSS - if you want to do this explicitly you have to do it in the markup as you described.

Most browsers will, however, look for a favicon.ico file on the root of the web site - so if you access most browsers will look for automatically.

Fixing a systemd service 203/EXEC failure (no such file or directory)

To simplify, make sure to add a hash bang to the top of your ExecStart script, i.e.


python -u    

"starting Tomcat server 7 at localhost has encountered a prob"

  1. Close Eclipse
  2. Copy all files from TOMCAT/conf to WORKSPACE/Servers/Tomcat v7.0 Server at localhost-config
  3. Start Eclipse
  4. Expand the Servers project, click on the Tomcat 7 project and hit F5
  5. Start Tomcat from Eclipse

Showing data values on stacked bar chart in ggplot2

From ggplot 2.2.0 labels can easily be stacked by using position = position_stack(vjust = 0.5) in geom_text.

ggplot(Data, aes(x = Year, y = Frequency, fill = Category, label = Frequency)) +
  geom_bar(stat = "identity") +
  geom_text(size = 3, position = position_stack(vjust = 0.5))

enter image description here

Also note that "position_stack() and position_fill() now stack values in the reverse order of the grouping, which makes the default stack order match the legend."

Answer valid for older versions of ggplot:

Here is one approach, which calculates the midpoints of the bars.


# calculate midpoints of bars (simplified using comment by @DWin)
Data <- ddply(Data, .(Year), 
   transform, pos = cumsum(Frequency) - (0.5 * Frequency)

# library(dplyr) ## If using dplyr... 
# Data <- group_by(Data,Year) %>%
#    mutate(pos = cumsum(Frequency) - (0.5 * Frequency))

# plot bars and add text
p <- ggplot(Data, aes(x = Year, y = Frequency)) +
     geom_bar(aes(fill = Category), stat="identity") +
     geom_text(aes(label = Frequency, y = pos), size = 3)

Resultant chart

Display unescaped HTML in Vue.js

You can use the directive v-html to show it. like this:

<td v-html="desc"></td>

Android Split string

android split string by comma

String data = "1,Diego Maradona,Footballer,Argentina";
String[] items = data.split(",");
for (String item : items)
    System.out.println("item = " + item);

Center the nav in Twitter Bootstrap

Possible duplicate of Modify twitter bootstrap navbar. I guess this is what you are looking for (copied):

.navbar .nav,
.navbar .nav > li {
  *display:inline; /* ie7 fix */
  *zoom:1; /* hasLayout ie7 trigger */
  vertical-align: top;

.navbar-inner {

As stated in the linked answer, you should make a new class with these properties and add it to the nav div.

Installing jQuery?

It tells you at the very start of the tutorial linked from the jQuery homepage.

How to extend / inherit components?

As far as I know component inheritance has not been implemented yet in Angular 2 and I'm not sure if they have plans to, however since Angular 2 is using typescript (if you've decided to go that route) you can use class inheritance by doing class MyClass extends OtherClass { ... }. For component inheritance I'd suggest getting involved with the Angular 2 project by going to and submitting a feature request!

Getting attribute of element in ng-click function in angularjs

Addition to the answer of Brett DeWoody: (which is updated now)

var dataValue =;

Works fine in IE(9+) and Chrome, but Firefox does not know the srcElement property. I found:

var dataValue =;

Works in IE, Chrome and FF, I did not test Safari.

Batch Extract path and filename from a variable

if you want infos from the actual running batchfile, try this :

@echo off
set myNameFull=%0
echo myNameFull     %myNameFull%
set myNameShort=%~n0
echo myNameShort    %myNameShort%
set myNameLong=%~nx0
echo myNameLong     %myNameLong%
set myPath=%~dp0
echo myPath         %myPath%
set myLogfileWpath=%myPath%%myNameShort%.log
echo myLogfileWpath %myLogfileWpath%

more samples? C:> HELP CALL

%0 = parameter 0 = batchfile %1 = parameter 1 - 1st par. passed to batchfile... so you can try that stuff (e.g. "~dp") between 1st (e.g. "%") and last (e.g. "1") also for parameters

How can I get npm start at a different directory?

I came here from google so it might be relevant to others: for yarn you could use:

yarn --cwd /path/to/your/app run start 

Terminating a script in PowerShell

Write-Error is for non-terminating errors and throw is for terminating errors

The Write-Error cmdlet declares a non-terminating error. By default, errors are sent in the error stream to the host program to be displayed, along with output.

Non-terminating errors write an error to the error stream, but they do not stop command processing. If a non-terminating error is declared on one item in a collection of input items, the command continues to process the other items in the collection.

To declare a terminating error, use the Throw keyword. For more information, see about_Throw (

How to document a method with parameter(s)?



Update: Since Python 3.5 you can use type hints which is a compact, machine-readable syntax:

from typing import Dict, Union

def foo(i: int, d: Dict[str, Union[str, int]]) -> int:
    Explanation: this function takes two arguments: `i` and `d`.
    `i` is annotated simply as `int`. `d` is a dictionary with `str` keys
    and values that can be either `str` or `int`.

    The return type is `int`.


The main advantage of this syntax is that it is defined by the language and that it's unambiguous, so tools like PyCharm can easily take advantage from it.

Create empty data frame with column names by assigning a string vector?

How about:

df <- data.frame(matrix(ncol = 3, nrow = 0))
x <- c("name", "age", "gender")
colnames(df) <- x

To do all these operations in one-liner:

setNames(data.frame(matrix(ncol = 3, nrow = 0)), c("name", "age", "gender"))

#[1] name   age    gender
#<0 rows> (or 0-length row.names)


data.frame(matrix(ncol=3,nrow=0, dimnames=list(NULL, c("name", "age", "gender"))))

What does `unsigned` in MySQL mean and when to use it?

MySQL says:

All integer types can have an optional (nonstandard) attribute UNSIGNED. Unsigned type can be used to permit only nonnegative numbers in a column or when you need a larger upper numeric range for the column. For example, if an INT column is UNSIGNED, the size of the column's range is the same but its endpoints shift from -2147483648 and 2147483647 up to 0 and 4294967295.

When do I use it ?

Ask yourself this question: Will this field ever contain a negative value?
If the answer is no, then you want an UNSIGNED data type.

A common mistake is to use a primary key that is an auto-increment INT starting at zero, yet the type is SIGNED, in that case you’ll never touch any of the negative numbers and you are reducing the range of possible id's to half.

How to Add Date Picker To VBA UserForm

Just throw some light in to some issues related to this control.

Date picker is not a standard control that comes with office package. So developers encountered issues like missing date picker controls when application deployed in some other machiens/versions of office. In order to use it you have to activate the reference to the .dll, .ocx file that contains it.

In the event of a missing date picker, you have to replace MSCOMCT2.OCX file in System or System32 directory and register it properly. Try this link to do the proper replacement of the file.

In the VBA editor menu bar-> select tools-> references and then find the date picker reference and check it.

If you need the file, download MSCOMCT2.OCX from here.