Programs & Examples On #Properties

A property, in some object-oriented programming languages, is a special sort of class member, intermediate between a field (or data member) and a method. Properties are read and written like fields, but property reads and writes are (usually) translated to get and set method calls.

How to add property to a class dynamically?

You don't need to use a property for that. Just override __setattr__ to make them read only.

class C(object):
    def __init__(self, keys, values):
        for (key, value) in zip(keys, values):
            self.__dict__[key] = value

    def __setattr__(self, name, value):
        raise Exception("It is read only!")


>>> c = C('abc', [1,2,3])
>>> c.a
>>> c.b
>>> c.c
>>> c.d
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'C' object has no attribute 'd'
>>> c.d = 42
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 6, in __setattr__
Exception: It is read only!
>>> c.a = 'blah'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 6, in __setattr__
Exception: It is read only!

How can I find a specific element in a List<T>?

You can also use LINQ extensions:

string id = "hello";
MyClass result = list.Where(m => m.GetId() == id).First();

How does the @property decorator work in Python?

A property can be declared in two ways.

  • Creating the getter, setter methods for an attribute and then passing these as argument to property function
  • Using the @property decorator.

You can have a look at few examples I have written about properties in python.

Access elements in json object like an array

I found a straight forward way of solving this, with the use of JSON.parse.

Let's assume the json below is inside the variable jsontext.

  ["Blankaholm", "Gamleby"],
  ["2012-10-23", "2012-10-22"],
  ["Blankaholm. Under natten har det varit inbrott", "E22 i med Gamleby. Singelolycka. En bilist har.],
  ["57.586174","16.521841"], ["57.893162","16.406090"]

The solution is this:

var parsedData = JSON.parse(jsontext);

Now I can access the elements the following way:

var cities = parsedData[0];

Property getters and setters

Setters/getters in Swift are quite different than ObjC. The property becomes a computed property which means it does not have a backing variable such as _x as it would in ObjC.

In the solution code below you can see the xTimesTwo does not store anything, but simply computes the result from x.

See Official docs on computed properties.

The functionality you want might also be Property Observers.

What you need is:

var x: Int

var xTimesTwo: Int {
    set {
       x = newValue / 2
    get {
        return x * 2

You can modify other properties within the setter/getters, which is what they are meant for.

How to use Java property files?

In Java 8 to get all your properties

public static Map<String, String> readPropertiesFile(String location) throws Exception {

    Map<String, String> properties = new HashMap<>();

    Properties props = new Properties();
    props.load(new FileInputStream(new File(location)));

    props.forEach((key, value) -> {
        properties.put(key.toString(), value.toString());

    return properties;

Uncaught Typeerror: cannot read property 'innerHTML' of null

If the script is in the head of your HTML document, the body of your HTML document has not yet been created by the browser, regardless of what will eventually be there (the same result occurs if your script is in the HTML file but above the element). When your variable tries to find document.getElementById("status") it does not yet exist, and so it returns a value of null. When you then use the variable later in your code, the initial value (null) is used and not the current one, because nothing has updated the variable.

I didn't want to move my script link out of the HTML head, so instead I did this in my JS file:

var idPost //define a global variable
function updateVariables(){
    idPost = document.getElementById("status").innerHTML; //update the global variable

And this in the HTML file:

<body onload="updateVariables()">

If you already have an onload function in place, you can just add the additional line to it or call the function.

If you don't want the variable to be global, define it locally in the function that you are trying to run and make sure the function is not called before the page has fully loaded.

How to add a Java Properties file to my Java Project in Eclipse

If you are working with core java, create your file(.properties) by right clicking your project. If the file is present inside your package or src folder it will throw an file not found error

Java system properties and environment variables

I think the difference between the two boils down to access. Environment variables are accessible by any process and Java system properties are only accessible by the process they are added to.

Also as Bohemian stated, env variables are set in the OS (however they 'can' be set through Java) and system properties are passed as command line options or set via setProperty().

Kotlin - Property initialization using "by lazy" vs. "lateinit"

Everything is correct above, but one of facts simple explanation LAZY----There are cases when you want to delay the creation of an instance of your object until its first usage. This technique is known as lazy initialization or lazy instantiation. The main purpose of lazy initialization is to boost performance and reduce your memory footprint. If instantiating an instance of your type carries a large computational cost and the program might end up not actually using it, you would want to delay or even avoid wasting CPU cycles.

@synthesize vs @dynamic, what are the differences?

One thing want to add is that if a property is declared as @dynamic it will not occupy memory (I confirmed with allocation instrument). A consequence is that you can declare property in class category.

Comparing object properties in c#

Make sure objects aren't null.

Having obj1 and obj2:

if(obj1 == null )
   return false;
return obj1.Equals( obj2 );

How to loop through all the properties of a class?

Here's another way to do it, using a LINQ lambda:


SomeObject.GetType().GetProperties().ToList().ForEach(x => Console.WriteLine($"{x.Name} = {x.GetValue(SomeObject, null)}"));


SomeObject.GetType.GetProperties.ToList.ForEach(Sub(x) Console.WriteLine($"{x.Name} = {x.GetValue(SomeObject, Nothing)}"))

How to escape the equals sign in properties files

Moreover, Please refer to load(Reader reader) method from Property class on javadoc

In load(Reader reader) method documentation it says

The key contains all of the characters in the line starting with the first non-white space character and up to, but not including, the first unescaped '=', ':', or white space character other than a line terminator. All of these key termination characters may be included in the key by escaping them with a preceding backslash character; for example,


would be the two-character key ":=". Line terminator characters can be included using \r and \n escape sequences. Any white space after the key is skipped; if the first non-white space character after the key is '=' or ':', then it is ignored and any white space characters after it are also skipped. All remaining characters on the line become part of the associated element string; if there are no remaining characters, the element is the empty string "". Once the raw character sequences constituting the key and element are identified, escape processing is performed as described above.

Hope that helps.

What is the attribute property="og:title" inside meta tag?

og:title is one of the open graph meta tags. og:... properties define objects in a social graph. They are used for example by Facebook.

og:title stands for the title of your object as it should appear within the graph (see here for more )

C# Iterate through Class properties

I tried what Samuel Slade has suggested. Didn't work for me. The PropertyInfo list was coming as empty. So, I tried the following and it worked for me.

    Type type = typeof(Record);
    FieldInfo[] properties = type.GetFields();
    foreach (FieldInfo property in properties) {

What's the difference between the atomic and nonatomic attributes?

The last two are identical; "atomic" is the default behavior (note that it is not actually a keyword; it is specified only by the absence of nonatomic -- atomic was added as a keyword in recent versions of llvm/clang).

Assuming that you are @synthesizing the method implementations, atomic vs. non-atomic changes the generated code. If you are writing your own setter/getters, atomic/nonatomic/retain/assign/copy are merely advisory. (Note: @synthesize is now the default behavior in recent versions of LLVM. There is also no need to declare instance variables; they will be synthesized automatically, too, and will have an _ prepended to their name to prevent accidental direct access).

With "atomic", the synthesized setter/getter will ensure that a whole value is always returned from the getter or set by the setter, regardless of setter activity on any other thread. That is, if thread A is in the middle of the getter while thread B calls the setter, an actual viable value -- an autoreleased object, most likely -- will be returned to the caller in A.

In nonatomic, no such guarantees are made. Thus, nonatomic is considerably faster than "atomic".

What "atomic" does not do is make any guarantees about thread safety. If thread A is calling the getter simultaneously with thread B and C calling the setter with different values, thread A may get any one of the three values returned -- the one prior to any setters being called or either of the values passed into the setters in B and C. Likewise, the object may end up with the value from B or C, no way to tell.

Ensuring data integrity -- one of the primary challenges of multi-threaded programming -- is achieved by other means.

Adding to this:

atomicity of a single property also cannot guarantee thread safety when multiple dependent properties are in play.


 @property(atomic, copy) NSString *firstName;
 @property(atomic, copy) NSString *lastName;
 @property(readonly, atomic, copy) NSString *fullName;

In this case, thread A could be renaming the object by calling setFirstName: and then calling setLastName:. In the meantime, thread B may call fullName in between thread A's two calls and will receive the new first name coupled with the old last name.

To address this, you need a transactional model. I.e. some other kind of synchronization and/or exclusion that allows one to exclude access to fullName while the dependent properties are being updated.

What properties can I use with

If you were to inspect the with firebug or chrome's developer tools you would see for a span element (e.g. the following properties) it will have whatever properties any element has. It depends what the target element is: HTMLSpanElement

attributes: NamedNodeMap
baseURI: "file:///C:/Test.html"
childElementCount: 0
childNodes: NodeList[1]
children: HTMLCollection[0]
classList: DOMTokenList
className: ""
clientHeight: 36
clientLeft: 1
clientTop: 1
clientWidth: 1443
contentEditable: "inherit"
dataset: DOMStringMap
dir: ""
draggable: false
firstChild: Text
firstElementChild: null
hidden: false
id: ""
innerHTML: "click"
innerText: "click"
isContentEditable: false
lang: ""
lastChild: Text
lastElementChild: null
localName: "span"
namespaceURI: ""
nextElementSibling: null
nextSibling: null
nodeName: "SPAN"
nodeType: 1
nodeValue: null
offsetHeight: 38
offsetLeft: 26
offsetParent: HTMLBodyElement
offsetTop: 62
offsetWidth: 1445
onabort: null
onbeforecopy: null
onbeforecut: null
onbeforepaste: null
onblur: null
onchange: null
onclick: null
oncontextmenu: null
oncopy: null
oncut: null
ondblclick: null
ondrag: null
ondragend: null
ondragenter: null
ondragleave: null
ondragover: null
ondragstart: null
ondrop: null
onerror: null
onfocus: null
oninput: null
oninvalid: null
onkeydown: null
onkeypress: null
onkeyup: null
onload: null
onmousedown: null
onmousemove: null
onmouseout: null
onmouseover: null
onmouseup: null
onmousewheel: null
onpaste: null
onreset: null
onscroll: null
onsearch: null
onselect: null
onselectstart: null
onsubmit: null
onwebkitfullscreenchange: null
outerHTML: "<span>click</span>"
outerText: "click"
ownerDocument: HTMLDocument
parentElement: HTMLElement
parentNode: HTMLElement
prefix: null
previousElementSibling: null
previousSibling: null
scrollHeight: 36
scrollLeft: 0
scrollTop: 0
scrollWidth: 1443
spellcheck: true
style: CSSStyleDeclaration
tabIndex: -1
tagName: "SPAN"
textContent: "click"
title: ""
webkitdropzone: ""
__proto__: HTMLSpanElement

Updating property value in properties file without deleting other values

Properties prop = new Properties();
prop.load(...); // FileInputStream 
prop.setProperty("key", "value");; // FileOutputStream 

How do I access properties of a javascript object if I don't know the names?

You often will want to examine the particular properties of an instance of an object, without all of it's shared prototype methods and properties:

 Obj.prototype.toString= function(){
        var A= [];
        for(var p in this){
                A[A.length]= p+'='+this[p];

    return A.join(', ');

Specifying trust store information in spring boot

java properties "" and "" do not correspond to "" and "" from Spring boot "" ("application.yml")

so you can not set "" and "" simply by setting "" and "" in "" ("application.yml")

an alternative of setting "" and "" is by Spring boot Externalized Configuration

below are excerpts of my implementation :

Params class holds the external settings

public class Params{

    //default values, can be override by external settings
    public static String trustStorePath = "config/client-truststore.jks";
    public static String trustStorePassword = "wso2carbon";
    public static String keyStorePath = "config/wso2carbon.jks";
    public static String keyStorePassword = "wso2carbon";
    public static String defaultType = "JKS";
    public void setTrustStorePath(String trustStorePath){
        Params.trustStorePath = trustStorePath;
    public void settrustStorePassword(String trustStorePassword){

    public void setKeyStorePath(String keyStorePath){
        Params.keyStorePath = keyStorePath;
    public void setkeyStorePassword(String keyStorePassword){
        Params.keyStorePassword = keyStorePassword;
    public void setDefaultType(String defaultType){
        Params.defaultType = defaultType;

KeyStoreUtil class undertakes the settings of "" and ""

public class KeyStoreUtil {
    public static void setTrustStoreParams() {
        File filePath = new File( Params.trustStorePath);
        String tsp = filePath.getAbsolutePath();
        System.setProperty("", tsp);
        System.setProperty("", Params.trustStorePassword);
        System.setProperty("", Params.defaultType);


    public static void setKeyStoreParams() {
        File filePath = new File(Params.keyStorePath);
        String ksp = filePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", Params.keyStorePassword);


you get the setters executed within the startup function

public class ProfilesApplication {

    public static void main(String[] args) {
        KeyStoreUtil.setTrustStoreParams();, args);

Edited on 2018-10-03

you may also want to adopt the annotation "PostConstruct" as as an alternative to execute the setters

import javax.annotation.PostConstruct;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

public class GateApplication {

    public static void main(String[] args) {, args);
    void postConstruct(){
    private static void setTrustStoreParams() {
        File filePath = new File( Params.trustStorePath);
        String tsp = filePath.getAbsolutePath();
        System.setProperty("", tsp);
        System.setProperty("", Params.trustStorePassword);
        System.setProperty("", Params.defaultType);


    private static void setKeyStoreParams() {
        File filePath = new File(Params.keyStorePath);
        String ksp = filePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", Params.keyStorePassword);


the application.yml

   trustStorePath: config/client-truststore.jks
   trustStorePassword: wso2carbon
   keyStorePath: config/wso2carbon.jks
   keyStorePassword: wso2carbon
   defaultType: JKS

finally, within the running environment(deployment server), you create a folder named "config" under the same folder where the jar archive is stored .

within the "config" folder, you store "application.yml", "client-truststore.jks", and "wso2carbon.jks". done!

Update on 2018-11-27 about Spring boot 2.x.x

starting from spring boot 2.x.x, static properties are no longer supported, please see here. I personally do not think it a good move, because complex changes have to be made along the reference chain...

anyway, an implementation excerpt might look like this

the 'Params' class

    import org.springframework.stereotype.Component;
    import lombok.Data;
     * Params class represent all config parameters that can 
     * be external set by spring xml file
    public class Params{
        //default values, can be override by external settings
        public String trustStorePath = "config/client-truststore.jks";
        public String trustStorePassword = "wso2carbon";
        public String keyStorePath = "config/wso2carbon.jks";
        public String keyStorePassword = "wso2carbon";
        public String defaultType = "JKS";  

the 'Springboot application class' (with 'PostConstruct')

import javax.annotation.PostConstruct;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

public class BillingApplication {
    Params params;
    public static void main(String[] args) {, args);
    void postConstruct() {
        // set TrustStoreParams
        File trustStoreFilePath = new File(params.trustStorePath);
        String tsp = trustStoreFilePath.getAbsolutePath();
        System.setProperty("", tsp);
        System.setProperty("", params.trustStorePassword);
        System.setProperty("", params.defaultType);
        // set KeyStoreParams
        File keyStoreFilePath = new File(params.keyStorePath);
        String ksp = keyStoreFilePath.getAbsolutePath();
        System.setProperty("Security.KeyStore.Location", ksp);
        System.setProperty("Security.KeyStore.Password", params.keyStorePassword);

Property 'value' does not exist on type 'EventTarget'

Use currentValue instead, as the type of currentValue is EventTarget & HTMLInputElement.

Dynamically Add C# Properties at Runtime

you could deserialize your json string into a dictionary and then add new properties then serialize it.

 var jsonString = @"{}";

        var jsonDoc = JsonSerializer.Deserialize<Dictionary<string, object>>(jsonString);

        jsonDoc.Add("Name", "Khurshid Ali");


Create an array of integers property in Objective-C

You can put this in your .h file for your class and define it as property, in XCode 7:

@property int  (*stuffILike) [10];

Overriding fields or properties in subclasses

I did this...

namespace Core.Text.Menus
    public abstract class AbstractBaseClass
        public string SELECT_MODEL;
        public string BROWSE_RECORDS;
        public string SETUP;

namespace Core.Text.Menus
    public class English : AbstractBaseClass
        public English()
            base.SELECT_MODEL = "Select Model";
            base.BROWSE_RECORDS = "Browse Measurements";
            base.SETUP = "Setup Instrument";

This way you can still use fields.

C# : assign data to properties via constructor vs. instantiating

Both approaches call a constructor, they just call different ones. This code:

var albumData = new Album 
                     Name = "Albumius",
                     Artist = "Artistus",
                     Year = 2013

is syntactic shorthand for this equivalent code:

var albumData = new Album();
albumData.Name = "Albumius";
albumData.Artist = "Artistus";
albumData.Year = 2013;

The two are almost identical after compilation (close enough for nearly all intents and purposes). So if the parameterless constructor wasn't public:

public Album() { }

then you wouldn't be able to use the object initializer at all anyway. So the main question isn't which to use when initializing the object, but which constructor(s) the object exposes in the first place. If the object exposes two constructors (like the one in your example), then one can assume that both ways are equally valid for constructing an object.

Sometimes objects don't expose parameterless constructors because they require certain values for construction. Though in cases like that you can still use the initializer syntax for other values. For example, suppose you have these constructors on your object:

private Album() { }
public Album(string name)
    this.Name = name;

Since the parameterless constructor is private, you can't use that. But you can use the other one and still make use of the initializer syntax:

var albumData = new Album("Albumius")
                     Artist = "Artistus",
                     Year = 2013

The post-compilation result would then be identical to:

var albumData = new Album("Albumius");
albumData.Artist = "Artistus";
albumData.Year = 2013;

Change CSS class properties with jQuery

You can't change CSS properties directly with jQuery. But you can achieve the same effect in at least two ways.

Dynamically Load CSS from a File

function updateStyleSheet(filename) {
    newstylesheet = "style_" + filename + ".css";

    if ($("#dynamic_css").length == 0) {
        css = $("head").children(":last");

          id: "dynamic_css",
          rel:  "stylesheet",
          type: "text/css",
          href: newstylesheet
    } else {

The example above is copied from:

Dynamically Add a Style Element

$("head").append('<style type="text/css"></style>');
var newStyleElement = $("head").children(':last');

The example code is copied from this JSFiddle fiddle originally referenced by Alvaro in their comment.

Remove array element based on object property

We can remove the element based on the property using the below 2 approaches.

  1. Using filter method
testArray.filter(prop => prop.key !== 'Test Value')
  1. Using splice method. For this method we need to find the index of the propery.
const index = testArray.findIndex(prop => prop.key === 'Test Value')

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

It allows the Entity Framework to create a proxy around the virtual property so that the property can support lazy loading and more efficient change tracking. See What effect(s) can the virtual keyword have in Entity Framework 4.1 POCO Code First? for a more thorough discussion.

Edit to clarify "create a proxy around": By "create a proxy around" I'm referring specifically to what the Entity Framework does. The Entity Framework requires your navigation properties to be marked as virtual so that lazy loading and efficient change tracking are supported. See Requirements for Creating POCO Proxies.
The Entity Framework uses inheritance to support this functionality, which is why it requires certain properties to be marked virtual in your base class POCOs. It literally creates new types that derive from your POCO types. So your POCO is acting as a base type for the Entity Framework's dynamically created subclasses. That's what I meant by "create a proxy around".

The dynamically created subclasses that the Entity Framework creates become apparent when using the Entity Framework at runtime, not at static compilation time. And only if you enable the Entity Framework's lazy loading or change tracking features. If you opt to never use the lazy loading or change tracking features of the Entity Framework (which is not the default) then you needn't declare any of your navigation properties as virtual. You are then responsible for loading those navigation properties yourself, either using what the Entity Framework refers to as "eager loading", or manually retrieving related types across multiple database queries. You can and should use lazy loading and change tracking features for your navigation properties in many scenarios though.

If you were to create a standalone class and mark properties as virtual, and simply construct and use instances of those classes in your own application, completely outside of the scope of the Entity Framework, then your virtual properties wouldn't gain you anything on their own.

Edit to describe why properties would be marked as virtual

Properties such as:

 public ICollection<RSVP> RSVPs { get; set; }

Are not fields and should not be thought of as such. These are called getters and setters and at compilation time, they are converted into methods.

//Internally the code looks more like this:
public ICollection<RSVP> get_RSVPs()
    return _RSVPs;

public void set_RSVPs(RSVP value)
    _RSVPs = value;

private RSVP _RSVPs;

That's why they're marked as virtual for use in the Entity Framework, it allows the dynamically created classes to override the internally generated get and set functions. If your navigation property getter/setters are working for you in your Entity Framework usage, try revising them to just properties, recompile, and see if the Entity Framework is able to still function properly:

 public virtual ICollection<RSVP> RSVPs;

Set object property using reflection

Yes, using System.Reflection:

using System.Reflection;


    string prop = "name";
    PropertyInfo pi = myObject.GetType().GetProperty(prop);
    pi.SetValue(myObject, "Bob", null);

Maven2 property that indicates the parent directory

I accessed the dir above using ${basedir}..\src\

java.util.MissingResourceException: Can't find bundle for base name 'property_file name', locale en_US

The simplest code would be like, keep your properties files into resources folder, either in src/main/resource or in src/test/resource. Then use below code to read properties files:

public class Utilities {
    static {
        rb1 = ResourceBundle.getBundle("fileNameWithoutExtension"); 
              // do not use .properties extension
    public static String getConfigProperties(String keyString) {
        return rb1.getString(keyString);

Get name of property as a string

Based on the answer which is already in the question and on this article: I am presenting my solution to this problem:

public static class PropertyNameHelper
    /// <summary>
    /// A static method to get the Propertyname String of a Property
    /// It eliminates the need for "Magic Strings" and assures type safety when renaming properties.
    /// See:
    /// </summary>
    /// <example>
    /// // Static Property
    /// string name = PropertyNameHelper.GetPropertyName(() => SomeClass.SomeProperty);
    /// // Instance Property
    /// string name = PropertyNameHelper.GetPropertyName(() => someObject.SomeProperty);
    /// </example>
    /// <typeparam name="T"></typeparam>
    /// <param name="propertyLambda"></param>
    /// <returns></returns>
    public static string GetPropertyName<T>(Expression<Func<T>> propertyLambda)
        var me = propertyLambda.Body as MemberExpression;

        if (me == null)
            throw new ArgumentException("You must pass a lambda of the form: '() => Class.Property' or '() => object.Property'");

        return me.Member.Name;
    /// <summary>
    /// Another way to get Instance Property names as strings.
    /// With this method you don't need to create a instance first.
    /// See the example.
    /// See:
    /// </summary>
    /// <example>
    /// string name = PropertyNameHelper((Firma f) => f.Firmenumsatz_Waehrung);
    /// </example>
    /// <typeparam name="T"></typeparam>
    /// <typeparam name="TReturn"></typeparam>
    /// <param name="expression"></param>
    /// <returns></returns>
    public static string GetPropertyName<T, TReturn>(Expression<Func<T, TReturn>> expression)
        MemberExpression body = (MemberExpression)expression.Body;
        return body.Member.Name;

And a Test which also shows the usage for instance and static properties:

public class PropertyNameHelperTest
    private class TestClass
        public static string StaticString { get; set; }
        public string InstanceString { get; set; }

    public void TestGetPropertyName()
        Assert.AreEqual("StaticString", PropertyNameHelper.GetPropertyName(() => TestClass.StaticString));

        Assert.AreEqual("InstanceString", PropertyNameHelper.GetPropertyName((TestClass t) => t.InstanceString));

Shortcut to create properties in Visual Studio?

Start from:

private int myVar;

When you select "myVar" and right click then select "Refactor" and select "Encapsulate Field".

It will automatically create:

    get { return myVar; }
    set { myVar = value; }

Or you can shortcut it by pressing Ctrl + R + E.

Properties file with a list as the value for an individual key

Create a wrapper around properties and assume your A value has keys A.1, A.2, etc. Then when asked for A your wrapper will read all the A.* items and build the list. HTH

Using a BOOL property

Apple recommends for stylistic purposes.If you write this code:

@property (nonatomic,assign) BOOL working;

Then you can not use [object isWorking].
It will show an error. But if you use below code means

@property (assign,getter=isWorking) BOOL working;

So you can use [object isWorking] .

Modifying CSS class property values on the fly with JavaScript / jQuery

I've got a solution for changing a value in specific CSS class. But it only works if you keep your CSS in the tag. If you just keep a link to your CSS from external files ex.

<style src='script.js'></style>

this solution won't work.

If your css looks like this for example:

<style id='style'>
.foo {

You can change a value of the tag using JS/jQuery.

I've written a function, perhaps it's not the best one but it works. You can improve it if you want.

function replaceClassProp(cl,prop,val){

if(!cl || !prop || !val){console.error('Wrong function arguments');return false;}

// Select style tag value

var tag = '#style';

    var style = $(tag).text();
    var str = style;

// Find the class you want to change
    var n = str.indexOf('.'+cl);
    str = str.substr(n,str.length);
    n = str.indexOf('}');
    str = str.substr(0,n+1);

    var before = str;

// Find specific property

    n = str.indexOf(prop);
    str = str.substr(n,str.length);
    n = str.indexOf(';');
    str = str.substr(0,n+1);

// Replace the property with values you selected

    var after = before.replace(str,prop+':'+val+';');

// Submit changes



Then just change the tag variable into your style tag id and exegute:


The difference between this and $('.foo').css('height','50px'); is that when you do it with css method of jQuery, all elements that have .foo class will have visible style='height:50px' in DOM. If you do it my way, elements are untouched and the only thing youll see is class='foo'


  • Clear DOM
  • You can modify the property you want without replacing the whole style


  • Only internal CSS
  • You have to find specific style tag you want to edit

Hope it helps anyhow.

How to read data from java properties file using Spring Boot

You can use @PropertySource to externalize your configuration to a properties file. There is number of way to do get properties:

1. Assign the property values to fields by using @Value with PropertySourcesPlaceholderConfigurer to resolve ${} in @Value:

public class ApplicationConfiguration {

    private String gMapReportUrl;

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


2. Get the property values by using Environment:

public class ApplicationConfiguration {

    private Environment env;

    public void foo() {


Hope this can help

Using @property versus getters and setters

In complex projects I prefer using read-only properties (or getters) with explicit setter function:

class MyClass(object):
def my_attr(self):

def set_my_attr(self, value):

In long living projects debugging and refactoring takes more time than writing the code itself. There are several downsides for using @property.setter that makes debugging even harder:

1) python allows creating new attributes for an existing object. This makes a following misprint very hard to track:

my_object.my_atttr = 4.

If your object is a complicated algorithm then you will spend quite some time trying to find out why it doesn't converge (notice an extra 't' in the line above)

2) setter sometimes might evolve to a complicated and slow method (e.g. hitting a database). It would be quite hard for another developer to figure out why the following function is very slow. He might spend a lot of time on profiling do_something() method, while my_object.my_attr = 4. is actually the cause of slowdown:

def slow_function(my_object):
    my_object.my_attr = 4.

Sorting objects by property values

Let us say we have to sort a list of objects in ascending order based on a particular property, in this example lets say we have to sort based on the "name" property, then below is the required code :

var list_Objects = [{"name"="Bob"},{"name"="Jay"},{"name"="Abhi"}];
Console.log(list_Objects);   //[{"name"="Bob"},{"name"="Jay"},{"name"="Abhi"}]
        return a["name"].localeCompare(b["name"]); 
Console.log(list_Objects);  //[{"name"="Abhi"},{"name"="Bob"},{"name"="Jay"}]

What is the { get; set; } syntax in C#?

It is a shortcut to expose data members as public so that you don't need to explicitly create a private data members. C# will creates a private data member for you.

You could just make your data members public without using this shortcut but then if you decided to change the implementation of the data member to have some logic then you would need to break the interface. So in short it is a shortcut to create more flexible code.

How to enumerate an object's properties in Python?

If you're looking for reflection of all properties, the answers above are great.

If you're simply looking to get the keys of a dictionary (which is different from an 'object' in Python), use


my_dict = {'abc': {}, 'def': 12, 'ghi': 'string' }
> ['abc', 'def', 'ghi']

Getting the object's property name

Using Object.keys() function for acquiring properties from an Object, and it can help search property by name, for example:

const Products = function(){
    this.Product = "Product A";
    this.Price = 9.99;
    this.Quantity = 112;

// Simple find function case insensitive
let findPropByName = function(data, propertyName){
 let props = [];
 Object.keys(data).forEach(element => {
    return props.push(element.toLowerCase());
  let i = props.indexOf(propertyName.toLowerCase());

  if(i > -1){
    return props[i];
  return false;

// calling the function
let products = new Products();
console.log(findPropByName(products, 'quantity'));

Generic Property in C#

You would need to create a generic class named MyProp. Then, you will need to add implicit or explicit cast operators so you can get and set the value as if it were the type specified in the generic type parameter. These cast operators can do the extra work that you need.

How to use BeanUtils.copyProperties?

As you can see in the below source code, BeanUtils.copyProperties internally uses reflection and there's additional internal cache lookup steps as well which is going to add cost wrt performance

 private static void copyProperties(Object source, Object target, @Nullable Class<?> editable,
                @Nullable String... ignoreProperties) throws BeansException {

            Assert.notNull(source, "Source must not be null");
            Assert.notNull(target, "Target must not be null");

            Class<?> actualEditable = target.getClass();
            if (editable != null) {
                if (!editable.isInstance(target)) {
                    throw new IllegalArgumentException("Target class [" + target.getClass().getName() +
                            "] not assignable to Editable class [" + editable.getName() + "]");
                actualEditable = editable;
            **PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable);**
            List<String> ignoreList = (ignoreProperties != null ? Arrays.asList(ignoreProperties) : null);

            for (PropertyDescriptor targetPd : targetPds) {
                Method writeMethod = targetPd.getWriteMethod();
                if (writeMethod != null && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {
                    PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName());
                    if (sourcePd != null) {
                        Method readMethod = sourcePd.getReadMethod();
                        if (readMethod != null &&
                                ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {
                            try {
                                if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {
                                Object value = readMethod.invoke(source);
                                if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {
                                writeMethod.invoke(target, value);
                            catch (Throwable ex) {
                                throw new FatalBeanException(
                                        "Could not copy property '" + targetPd.getName() + "' from source to target", ex);

So it's better to use plain setters given the cost reflection

How to make a class property?

If you define classproperty as follows, then your example works exactly as you requested.

class classproperty(object):
    def __init__(self, f):
        self.f = f
    def __get__(self, obj, owner):
        return self.f(owner)

The caveat is that you can't use this for writable properties. While e.I = 20 will raise an AttributeError, Example.I = 20 will overwrite the property object itself.

C# Get/Set Syntax Usage

These are properties. You would use them like so:

Tom.Title = "Accountant";
string desc = Tom.Description;

But considering they are declared protected their visibility may be a concern.

react-router - pass props to handler component

You can also combine es6 and stateless functions to get a much cleaner result:

import Dashboard from './Dashboard';
import Comments from './Comments';

let dashboardWrapper = () => <Dashboard {...props} />,
    commentsWrapper = () => <Comments {...props} />,
    index = () => <div>
        <header>Some header</header>
        <RouteHandler />

routes = {
    component: index,
    path: '/',
    childRoutes: [
        path: 'comments',
        component: dashboardWrapper
      }, {
        path: 'dashboard',
        component: commentsWrapper

How to efficiently count the number of keys/properties of an object in JavaScript?

If jQuery above does not work, then try


Sorting object property by values

There are many ways to do this, but since I didn't see any using reduce() I put it here. Maybe it seems utils to someone.

var list = {
    "you": 100,
    "me": 75,
    "foo": 116,
    "bar": 15

let result = Object.keys(list).sort((a,b)=>list[a]>list[b]?1:-1).reduce((a,b)=> {a[b]=list[b]; return a},{});


Better way to represent array in java properties file

I can suggest using delimiters and using the


Example properties file:

MON=0800#Something#Something1, Something2

prop.load(new FileInputStream("\\\\Myseccretnetwork\\Project\\"));
String[]values = prop.get("MON").toString().split("#");

Hope that helps

Can I update a component's props in React.js?

if you use recompose, use mapProps to make new props derived from incoming props

Edit for example:

import { compose, mapProps } from 'recompose';

const SomeComponent = ({ url, onComplete }) => (
  {url ? (
    <View />
  ) : null}

export default compose(
  mapProps(({ url, storeUrl, history, ...props }) => ({
    onClose: () => {
    url: url || storeUrl,

How do I use Linq to obtain a unique list of properties from a list of objects?

When taking Distinct we have to cast into IEnumerable too. If list is model means, need to write code like this

 IEnumerable<T> ids = list.Select(x => x).Distinct();

How to check whether an object has certain method/property?

It is an old question, but I just ran into it. Type.GetMethod(string name) will throw an AmbiguousMatchException if there is more than one method with that name, so we better handle that case

public static bool HasMethod(this object objectToCheck, string methodName)
        var type = objectToCheck.GetType();
        return type.GetMethod(methodName) != null;
        // ambiguous means there is more than one result,
        // which means: a method with that name does exist
        return true;

Is there a “not in” operator in JavaScript for checking object properties?

Personally I find

if (id in tutorTimes === false) { ... }

easier to read than

if (!(id in tutorTimes)) { ... }

but both will work.

c# foreach (property in object)... Is there a simple way of doing this?

Give this a try:

foreach (PropertyInfo propertyInfo in obj.GetType().GetProperties())
   // do stuff here

Also please note that Type.GetProperties() has an overload which accepts a set of binding flags so you can filter out properties on a different criteria like accessibility level, see MSDN for more details: Type.GetProperties Method (BindingFlags) Last but not least don't forget to add the "system.Reflection" assembly reference.

For instance to resolve all public properties:

foreach (var propertyInfo in obj.GetType()
                                        | BindingFlags.Instance))
   // do stuff here

Please let me know whether this works as expected.

How to get the list of properties of a class?

Try this:

var model = new MyObject();
foreach (var property in model.GetType().GetProperties())
    var descricao = property;
    var type = property.PropertyType.Name;

Properties file in python (similar to Java Properties)

I have created a python module that is almost similar to the Properties class of Java ( Actually it is like the PropertyPlaceholderConfigurer in spring which lets you use ${variable-reference} to refer to already defined property )

EDIT : You may install this package by running the command(currently tested for python 3).
pip install property

The project is hosted on GitHub

Example : ( Detailed documentation can be found here )

Let's say you have the following properties defined in file

foo = I am awesome
bar = ${chocolate}-bar
chocolate = fudge

Code to load the above properties

from properties.p import Property

prop = Property()
# Simply load it into a dictionary
dic_prop = prop.load_property_files('')

Dynamically access object property using variable

You can achieve this in quite a few different ways.

let foo = {
    bar: 'Hello World'

The bracket notation is specially powerful as it let's you access a property based on a variable:

let foo = {
    bar: 'Hello World'

let prop = 'bar';


This can be extended to looping over every property of an object. This can be seem redundant due to newer JavaScript constructs such as for ... of ..., but helps illustrate a use case:

let foo = {
    bar: 'Hello World',
    baz: 'How are you doing?',
    last: 'Quite alright'

for (let prop in foo.getOwnPropertyNames()) {

Both dot and bracket notation also work as expected for nested objects:

let foo = {
    bar: {
        baz: 'Hello World'

Object destructuring

We could also consider object destructuring as a means to access a property in an object, but as follows:

let foo = {
    bar: 'Hello World',
    baz: 'How are you doing?',
    last: 'Quite alright'

let prop = 'last';
let { bar, baz, [prop]: customName } = foo;

// bar = 'Hello World'
// baz = 'How are you doing?'
// customName = 'Quite alright'

Using multiple property files (via PropertyPlaceholderConfigurer) in multiple projects/modules

I tried the solution below, it works on my machine.

<context:property-placeholder location="classpath*" ignore-unresolvable="true" order="1" />

<context:property-placeholder location="classpath*" order="2"/>

In case multiple elements are present in the Spring context, there are a few best practices that should be followed:

the order attribute needs to be specified to fix the order in which these are processed by Spring all property placeholders minus the last one (highest order) should have ignore-unresolvable=”true” to allow the resolution mechanism to pass to others in the context without throwing an exception


Objective-C ARC: strong vs retain and weak vs assign

As far as I know, strong and retain are synonyms, so they do exactly the same.

Then the weak is almost like assign, but automatically set to nil after the object, it is pointing to, is deallocated.

That means, you can simply replace them.

However, there is one special case I've encountered, where I had to use assign, rather than weak. Let's say we have two properties delegateAssign and delegateWeak. In both is stored our delegate, that is owning us by having the only strong reference. The delegate is deallocating, so our -dealloc method is called too.

// Our delegate is deallocating and there is no other strong ref.
- (void)dealloc {
    [delegateWeak doSomething];
    [delegateAssign doSomething];

The delegate is already in deallocation process, but still not fully deallocated. The problem is that weak references to him are already nullified! Property delegateWeak contains nil, but delegateAssign contains valid object (with all properties already released and nullified, but still valid).

// Our delegate is deallocating and there is no other strong ref.
- (void)dealloc {
    [delegateWeak doSomething]; // Does nothing, already nil.
    [delegateAssign doSomething]; // Successful call.

It is quite special case, but it reveal us how those weak variables work and when they are nullified.

VB.Net Properties - Public Get, Private Set

    Public Property Name() As String
            Return _name
        End Get
        Private Set(ByVal value As String)
            _name = value
        End Set
   End Property

What is the difference between attribute and property?

In Python...

class X( object ):
    def __init__( self ):
    def getAttr( self ):
        return self.attribute
    def setAttr( self, value ):
        self.attribute= value
    property_name= property( getAttr, setAttr )

A property is a single attribute-like name that wraps a collection of setter, getter (and deleter) functions.

An attribute is usually a single object within another object.

Having said that, however, Python gives you methods like __getattr__ which allow you extend the definition of "attribute".

Bottom Line - they're almost synonymous. Python makes a technical distinction in how they're implemented.

Properties private set;

        new Person(dr.GetInt32(1), dr.GetInt32(0), dr.GetString(2)));


public class Person
    public Person(int age, int id, string name) 
        Age = age;
        Id = id;
        Name = name;

User Control - Custom Properties

Just add public properties to the user control.

You can add [Category("MyCategory")] and [Description("A property that controls the wossname")] attributes to make it nicer, but as long as it's a public property it should show up in the property panel.

What is the difference between properties and attributes in HTML?

Difference HTML properties and attributes:

Let's first look at the definitions of these words before evaluating what the difference is in HTML:

English definition:

  • Attributes are referring to additional information of an object.
  • Properties are describing the characteristics of an object.

In HTML context:

When the browser parses the HTML, it creates a tree data structure wich basically is an in memory representation of the HTML. It the tree data structure contains nodes which are HTML elements and text. Attributes and properties relate to this is the following manner:

  • Attributes are additional information which we can put in the HTML to initialize certain DOM properties.
  • Properties are formed when the browser parses the HTML and generates the DOM. Each of the elements in the DOM have their own set of properties which are all set by the browser. Some of these properties can have their initial value set by HTML attributes. Whenever a DOM property changes which has influence on the rendered page, the page will be immediately re rendered

It is also important to realize that the mapping of these properties is not 1 to 1. In other words, not every attribute which we give on an HTML element will have a similar named DOM property.

Furthermore have different DOM elements different properties. For example, an <input> element has a value property which is not present on a <div> property.


Let's take the following HTML document:

 <!DOCTYPE html>
  <meta charset="utf-8">  <!-- charset is a attribute -->
  <meta name="viewport" content="width=device-width"> <!-- name and content are attributes -->
  <title>JS Bin</title>
<div id="foo" class="bar foobar">hi</div> <!-- id and class are attributes -->

Then we inspect the <div>, in the JS console:


We see the following DOM properties (chrome devtools, not all properties shown):

html properties and attributes

  • We can see that the attribute id in the HTML is now also a id property in the DOM. The id has been initialized by the HTML (although we could change it with javascript).
  • We can see that the class attribute in the HTML has no corresponding class property (class is reserved keyword in JS). But actually 2 properties, classList and className.

Get property value from string using reflection

public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
        var result = new List<KeyValuePair<string, string>>();
        if (item != null)
            var type = item.GetType();
            var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
            foreach (var pi in properties)
                var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
                if (selfValue != null)
                    result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
                    result.Add(new KeyValuePair<string, string>(pi.Name, null));
        return result;

This is a way to get all properties with their values in a List.

Error in Swift class: Property not initialized at super.init call


You can modify the code in your example like this:

var playerShip:PlayerShip!
var deltaPoint = CGPointZero

init(size: CGSize)
    super.init(size: size)

This is using an implicitly unwrapped optional.

In documentation we can read:

"As with optionals, if you don’t provide an initial value when you declare an implicitly unwrapped optional variable or property, it’s value automatically defaults to nil."

Access properties file programmatically with Spring?

This will resolve any nested properties.

public class Environment extends PropertyPlaceholderConfigurer {

 * Map that hold all the properties.
private Map<String, String> propertiesMap; 

 * Iterate through all the Property keys and build a Map, resolve all the nested values before building the map.
protected void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props) throws BeansException {
    super.processProperties(beanFactory, props);

    propertiesMap = new HashMap<String, String>();
    for (Object key : props.keySet()) {
        String keyStr = key.toString();
        String valueStr = beanFactory.resolveEmbeddedValue(placeholderPrefix + keyStr.trim() + DEFAULT_PLACEHOLDER_SUFFIX);
        propertiesMap.put(keyStr, valueStr);

 * This method gets the String value for a given String key for the property files.
 * @param name - Key for which the value needs to be retrieved.
 * @return Value
public String getProperty(String name) {
    return propertiesMap.get(name).toString();

Test for existence of nested JavaScript object key

You can also use tc39 optional chaining proposal together with babel 7 - tc39-proposal-optional-chaining

Code would look like this:

  const test = test?.level1?.level2?.level3;
  if (test) alert(test);

Load properties file in JAR?

For the record, this is documented in How do I add resources to my JAR? (illustrated for unit tests but the same applies for a "regular" resource):

To add resources to the classpath for your unit tests, you follow the same pattern as you do for adding resources to the JAR except the directory you place resources in is ${basedir}/src/test/resources. At this point you would have a project directory structure that would look like the following:

|-- pom.xml
`-- src
    |-- main
    |   |-- java
    |   |   `-- com
    |   |       `-- mycompany
    |   |           `-- app
    |   |               `--
    |   `-- resources
    |       `-- META-INF
    |           |--
    `-- test
        |-- java
        |   `-- com
        |       `-- mycompany
        |           `-- app
        |               `--
        `-- resources

In a unit test you could use a simple snippet of code like the following to access the resource required for testing:


// Retrieve resource
InputStream is = getClass().getResourceAsStream("/" );

// Do something with the resource


How do I enumerate the properties of a JavaScript object?

Use a loop to enumerate an object's properties, but be careful. The enumeration will return properties not just of the object being enumerated, but also from the prototypes of any parent objects.

var myObject = {foo: 'bar'};

for (var name in myObject) {

// results in a single alert of 'foo'

Object.prototype.baz = 'quux';

for (var name in myObject) {

// results in two alerts, one for 'foo' and one for 'baz'

To avoid including inherited properties in your enumeration, check hasOwnProperty():

for (var name in myObject) {
  if (myObject.hasOwnProperty(name)) {

Edit: I disagree with JasonBunting's statement that we don't need to worry about enumerating inherited properties. There is danger in enumerating over inherited properties that you aren't expecting, because it can change the behavior of your code.

It doesn't matter whether this problem exists in other languages; the fact is it exists, and JavaScript is particularly vulnerable since modifications to an object's prototype affects child objects even if the modification takes place after instantiation.

This is why JavaScript provides hasOwnProperty(), and this is why you should use it in order to ensure that third party code (or any other code that might modify a prototype) doesn't break yours. Apart from adding a few extra bytes of code, there is no downside to using hasOwnProperty().

How to configure log4j with a properties file

Since JVM arguments are eventually passed to your java program as system variables, you can use this code at the beginning of your execution point to edit the property and have log4j read the property you just set in system properties

try {
        System.setProperty("log4j.configuration", new File(System.getProperty("user.dir")+File.separator+"conf"+File.separator+"").toURI().toURL().toString());
    } catch (MalformedURLException e) {

Python read-only property

Here is a slightly different approach to read-only properties, which perhaps should be called write-once properties since they do have to get initialized, don't they? For the paranoid among us who worry about being able to modify properties by accessing the object's dictionary directly, I've introduced "extreme" name mangling:

from uuid import uuid4

class ReadOnlyProperty:
    def __init__(self, name): = name
        self.dict_name = uuid4().hex
        self.initialized = False

    def __get__(self, instance, cls):
        if instance is None:
            return self
            return instance.__dict__[self.dict_name]

    def __set__(self, instance, value):
        if self.initialized:
            raise AttributeError("Attempt to modify read-only property '%s'." %
        instance.__dict__[self.dict_name] = value
        self.initialized = True

class Point:
    x = ReadOnlyProperty('x')
    y = ReadOnlyProperty('y')
    def __init__(self, x, y):
        self.x = x
        self.y = y

if __name__ == '__main__':
        p = Point(2, 3)
        print(p.x, p.y)
        p.x = 9
    except Exception as e:

How to access property of anonymous type in C#?

You could iterate over the anonymous type's properties using Reflection; see if there is a "Checked" property and if there is then get its value.

See this blog post:

So something like:

foreach(object o in nodes)
    Type t = o.GetType();

    PropertyInfo[] pi = t.GetProperties(); 

    foreach (PropertyInfo p in pi)
        if (p.Name=="Checked" && !(bool)p.GetValue(o))

Spring application context external properties?

This blog can help you. The trick is to use SpEL (spring expression language) to read the system properties like user.home, to read user home directory using SpEL you could use
#{ systemProperties['user.home']} expression inside your bean elements. For example to access your properties file stored in your home directory you could use the following in your PropertyPlaceholderConfigurer, it worked for me.

 <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="locations">
        <value>file:#{ systemProperties['user.home']}/ur_folder/</value>

How can I specify system properties in Tomcat configuration on startup?

It's also possible letting a ServletContextListener set the System properties:

import java.util.Enumeration;
import javax.servlet.*;

public class SystemPropertiesHelper implements
        javax.servlet.ServletContextListener {
    private ServletContext context = null;

    public void contextInitialized(ServletContextEvent event) {
        context = event.getServletContext();
        Enumeration<String> params = context.getInitParameterNames();

        while (params.hasMoreElements()) {
          String param = (String) params.nextElement();
          String value = 
          if (param.startsWith("customPrefix.")) {
              System.setProperty(param, value);

    public void contextDestroyed(ServletContextEvent event) {

And then put this into your web.xml (should be possible for context.xml too)



It worked for me.

Inconsistent accessibility: property type is less accessible

Your class Delivery has no access modifier, which means it defaults to internal. If you then try to expose a property of that type as public, it won't work. Your type (class) needs to have the same, or higher access as your property.

More about access modifiers:

Does C# have extension properties?

Because I recently needed this, I looked at the source of the answer in:

c# extend class by adding properties

and created a more dynamic version:

public static class ObjectExtenders
    static readonly ConditionalWeakTable<object, List<stringObject>> Flags = new ConditionalWeakTable<object, List<stringObject>>();

    public static string GetFlags(this object objectItem, string key)
        return Flags.GetOrCreateValue(objectItem).Single(x => x.Key == key).Value;

    public static void SetFlags(this object objectItem, string key, string value)
        if (Flags.GetOrCreateValue(objectItem).Any(x => x.Key == key))
            Flags.GetOrCreateValue(objectItem).Single(x => x.Key == key).Value = value;
            Flags.GetOrCreateValue(objectItem).Add(new stringObject()
                Key = key,
                Value = value

    class stringObject
        public string Key;
        public string Value;

It can probably be improved a lot (naming, dynamic instead of string), I currently use this in CF 3.5 together with a hacky ConditionalWeakTable (

How to use a variable for a key in a JavaScript object literal?

ES5 implementation to assign keys is below:

var obj = Object.create(null),
    objArgs = (
      (objArgs = {}),
      (objArgs.someKey = {
        value: 'someValue'
      }), objArgs);

Object.defineProperties(obj, objArgs);

I've attached a snippet I used to convert to bare object.

var obj = {_x000D_
  'key1': 'value1',_x000D_
  'key2': 'value2',_x000D_
  'key3': [_x000D_
  'key4': {_x000D_
    'key5': 'value5'_x000D_
var bareObj = function(obj) {_x000D_
  var objArgs,_x000D_
    bareObj = Object.create(null);_x000D_
  Object.entries(obj).forEach(function([key, value]) {_x000D_
    var objArgs = (_x000D_
      (objArgs = {}),_x000D_
      (objArgs[key] = {_x000D_
        value: value_x000D_
      }), objArgs);_x000D_
    Object.defineProperties(bareObj, objArgs);_x000D_
  return {_x000D_
    input: obj,_x000D_
    output: bareObj_x000D_
if (!Object.entries) {_x000D_
  Object.entries = function(obj){_x000D_
    var arr = [];_x000D_
      arr.push([key, obj[key]]);_x000D_
    return arr;_x000D_

Read properties file outside JAR file

I did it by other way.

Properties prop = new Properties();
    try {

        File jarPath=new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath());
        String propertiesPath=jarPath.getParentFile().getAbsolutePath();
        System.out.println(" propertiesPath-"+propertiesPath);
        prop.load(new FileInputStream(propertiesPath+"/"));
    } catch (IOException e1) {
  1. Get Jar file path.
  2. Get Parent folder of that file.
  3. Use that path in InputStreamPath with your properties file name.

How to implement a read only property

I agree that the second way is preferable. The only real reason for that preference is the general preference that .NET classes not have public fields. However, if that field is readonly, I can't see how there would be any real objections other than a lack of consistency with other properties. The real difference between a readonly field and get-only property is that the readonly field provides a guarantee that its value will not change over the life of the object and a get-only property does not.

How to create an object property from a variable value in JavaScript?

ES6 introduces computed property names, which allow you to do

var myObj = {[a]: b};

Note browser support is currently negligible.

How to set a Javascript object values dynamically?

You can get the property the same way as you set it.

foo = {
 bar: "value"

You set the value foo["bar"] = "baz";

To get the value foo["bar"]

will return "baz".

Raise an event whenever a property's value changed?

Raising an event when a property changes is precisely what INotifyPropertyChanged does. There's one required member to implement INotifyPropertyChanged and that is the PropertyChanged event. Anything you implemented yourself would probably be identical to that implementation, so there's no advantage to not using it.

What is the difference between a field and a property?

The difference is clearly explained here.However, just to summarize and highlight :

The fields are encapsulated inside class for its internal operation whereas properties can be used for exposing the class to outside world in addition to other internal operations shown in the link shared.Additionally, if you want to load certain methods or user controls based on the value of a particular field, then the property will do it for you :

For example:

You can function below user control inside your page by simply assigning a value to the Id preperty of control in your aspx page as given below :

useMeId.Id=5 ---call the property of user control "UseMe.ascx"


<%@ Register Src=~/"UseMe.ascx" TagPrefix="uc" TagName="UseMe" %>
<uc:UseMe runat="Server" id="useMeId" />


private int currentId;

public int Id
         return currentId;
         currentId = value;
Private void LoadinitialData(int currentIdParam)
//your action


Get PHP class property by string

What you're asking about is called Variable Variables. All you need to do is store your string in a variable and access it like so:

$Class = 'MyCustomClass';
$Property = 'Name';
$List = array('Name');

$Object = new $Class();

// All of these will echo the same property
echo $Object->$Property;  // Evaluates to $Object->Name
echo $Object->{$List[0]}; // Use if your variable is in an array

Thread-safe List<T> property

Looking at the original sample one may guess that the intention was to be able to simply replace the list with the new one. The setter on the property tells us about it.

The Micrisoft's Thread-Safe Collections are for safely adding and removing items from collection. But if in the application logic you are intending to replace the collection with the new one, one may guess, again, that the adding and deleting functionality of the List is not required.

If this is the case then, the simple answer would be to use IReadOnlyList interface:

 private IReadOnlyList<T> _readOnlyList = new List<T>();

    private IReadOnlyList<T> MyT
       get { return _readOnlyList; }
       set { _readOnlyList = value; }

One doesn't need to use any locking in this situation because there is no way to modify the collection. If in the setter the "_readOnlyList = value;" will be replaced by something more complicated then the lock could be required.

Reading Properties file in Java

Based on your exception, the InputStream is null, this means the class loader is not finding your properties file. I'm guessing that is in the root of your project, if that's the case, you need a preceding slash:

InputStream stream = loader.getResourceAsStream("/");

Is there a way to specify a default property value in Spring XML?

The default value can be followed with a : after the property key, e.g.

<property name="port" value="${my.server.port:8080}" />

Or in java code:

private String myServerPort;


BTW, the Elvis Operator is only available within Spring Expression Language (SpEL),

Moq, SetupGet, Mocking a property

ColumnNames is a property of type List<String> so when you are setting up you need to pass a List<String> in the Returns call as an argument (or a func which return a List<String>)

But with this line you are trying to return just a string

input.SetupGet(x => x.ColumnNames).Returns(temp[0]);

which is causing the exception.

Change it to return whole list:

input.SetupGet(x => x.ColumnNames).Returns(temp);

Passing properties by reference in C#

I wrote a wrapper using the ExpressionTree variant and c#7 (if somebody is interested):

public class Accessor<T>
    private Action<T> Setter;
    private Func<T> Getter;

    public Accessor(Expression<Func<T>> expr)
        var memberExpression = (MemberExpression)expr.Body;
        var instanceExpression = memberExpression.Expression;
        var parameter = Expression.Parameter(typeof(T));

        if (memberExpression.Member is PropertyInfo propertyInfo)
            Setter = Expression.Lambda<Action<T>>(Expression.Call(instanceExpression, propertyInfo.GetSetMethod(), parameter), parameter).Compile();
            Getter = Expression.Lambda<Func<T>>(Expression.Call(instanceExpression, propertyInfo.GetGetMethod())).Compile();
        else if (memberExpression.Member is FieldInfo fieldInfo)
            Setter = Expression.Lambda<Action<T>>(Expression.Assign(memberExpression, parameter), parameter).Compile();
            Getter = Expression.Lambda<Func<T>>(Expression.Field(instanceExpression,fieldInfo)).Compile();


    public void Set(T value) => Setter(value);

    public T Get() => Getter();

And use it like:

var accessor = new Accessor<string>(() => myClient.WorkPhone);
Assert.Equal(accessor.Get(), "12345");

How do you merge two Git repositories?

If you want to put the files from a branch in repo B in a subtree of repo A and also preserve the history, keep reading. (In the example below, I am assuming that we want repo B's master branch merged into repo A's master branch.)

In repo A, first do the following to make repo B available:

git remote add B ../B # Add repo B as a new remote.
git fetch B

Now we create a brand new branch (with only one commit) in repo A that we call new_b_root. The resulting commit will have the files that were committed in the first commit of repo B's master branch but put in a subdirectory called path/to/b-files/.

git checkout --orphan new_b_root master
git rm -rf . # Remove all files.
git cherry-pick -n `git rev-list --max-parents=0 B/master`
mkdir -p path/to/b-files
git mv README path/to/b-files/
git commit --date="$(git log --format='%ai' $(git rev-list --max-parents=0 B/master))"

Explanation: The --orphan option to the checkout command checks out the files from A's master branch but doesn't create any commit. We could have selected any commit because next we clear out all the files anyway. Then, without committing yet (-n), we cherry-pick the first commit from B's master branch. (The cherry-pick preserves the original commit message which a straight checkout doesn't seem to do.) Then we create the subtree where we want to put all files from repo B. We then have to move all files that were introduced in the cherry-pick to the subtree. In the example above, there's only a README file to move. Then we commit our B-repo root commit, and, at the same time, we also preserve the timestamp of the original commit.

Now, we'll create a new B/master branch on top of the newly created new_b_root. We call the new branch b:

git checkout -b b B/master
git rebase -s recursive -Xsubtree=path/to/b-files/ new_b_root

Now, we merge our b branch into A/master:

git checkout master
git merge --allow-unrelated-histories --no-commit b
git commit -m 'Merge repo B into repo A.'

Finally, you can remove the B remote and temporary branches:

git remote remove B
git branch -D new_b_root b

The final graph will have a structure like this:

enter image description here

"No Content-Security-Policy meta tag found." error in my phonegap application

You have to add a CSP meta tag in the head section of your app's index.html

As per

Content Security Policy

Controls which network requests (images, XHRs, etc) are allowed to be made (via webview directly).

On Android and iOS, the network request whitelist (see above) is not able to filter all types of requests (e.g. <video> & WebSockets are not blocked). So, in addition to the whitelist, you should use a Content Security Policy <meta> tag on all of your pages.

On Android, support for CSP within the system webview starts with KitKat (but is available on all versions using Crosswalk WebView).

Here are some example CSP declarations for your .html pages:

<!-- Good default declaration:
    * gap: is required only on iOS (when using UIWebView) and is needed for JS->native communication
    * is required only on Android and is needed for TalkBack to function properly
    * Disables use of eval() and inline scripts in order to mitigate risk of XSS vulnerabilities. To change this:
        * Enable inline JS: add 'unsafe-inline' to default-src
        * Enable eval(): add 'unsafe-eval' to default-src
<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap:; style-src 'self' 'unsafe-inline'; media-src *">

<!-- Allow requests to -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'">

<!-- Enable all requests, inline styles, and eval() -->
<meta http-equiv="Content-Security-Policy" content="default-src *; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' 'unsafe-eval'">

<!-- Allow XHRs via https only -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self' https:">

<!-- Allow iframe to -->
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; frame-src 'self'">

Twitter bootstrap collapse: change display of toggle button

You do like this. the function return the old text.

            return old=='Read More' ?  'Read Less' : 'Read More';

VBA changing active workbook

Use ThisWorkbook which will refer to the original workbook which holds the code.

Alternatively at code start

Dim Wb As Workbook
Set Wb = ActiveWorkbook

sample code that activates all open books before returning to ThisWorkbook

Sub Test()
Dim Wb As Workbook
Dim Wb2 As Workbook
Set Wb = ThisWorkbook
For Each Wb2 In Application.Workbooks
End Sub

Python string.join(list) on object array rather than string array

You could use a list comprehension or a generator expression instead:

', '.join([str(x) for x in list])  # list comprehension
', '.join(str(x) for x in list)    # generator expression

Create a string with n characters

I think this is the less code it's possible, it uses Guava Joiner class:

Joiner.on("").join(Collections.nCopies(10, " "));

PostgreSQL: insert from another table

Very late answer, but I think my answer is more straight forward for specific use cases where users want to simply insert (copy) data from table A into table B:

INSERT INTO table_b (col1, col2, col3, col4, col5, col6)
SELECT col1, 'str_val', int_val, col4, col5, col6
FROM table_a

Deleting a pointer in C++

I believe you're not fully understanding how pointers work.
When you have a pointer pointing to some memory there are three different things you must understand:
- there is "what is pointed" by the pointer (the memory)
- this memory address
- not all pointers need to have their memory deleted: you only need to delete memory that was dynamically allocated (used new operator).


int *ptr = new int; 
// ptr has the address of the memory.
// at this point, the actual memory doesn't have anything.
*ptr = 8;
// you're assigning the integer 8 into that memory.
delete ptr;
// you are only deleting the memory.
// at this point the pointer still has the same memory address (as you could
//   notice from your 2nd test) but what inside that memory is gone!

When you did

ptr = NULL;
// you didn't delete the memory
// you're only saying that this pointer is now pointing to "nowhere".
// the memory that was pointed by this pointer is now lost.

C++ allows that you try to delete a pointer that points to null but it doesn't actually do anything, just doesn't give any error.

How can I get a specific field of a csv file?

import csv
mycsv = csv.reader(open(myfilepath))
for row in mycsv:
   text = row[1]

Following the comments to the SO question here, a best, more robust code would be:

import csv
with open(myfilepath, 'rb') as f:
    mycsv = csv.reader(f)
    for row in mycsv:
        text = row[1]

Update: If what the OP actually wants is the last string in the last row of the csv file, there are several aproaches that not necesarily needs csv. For example,

fulltxt = open(mifilepath, 'rb').read()
laststring = fulltxt.split(',')[-1]

This is not good for very big files because you load the complete text in memory but could be ok for small files. Note that laststring could include a newline character so strip it before use.

And finally if what the OP wants is the second string in line n (for n=2):

Update 2: This is now the same code than the one in the answer from J.F.Sebastian. (The credit is for him):

import csv
line_number = 2     
with open(myfilepath, 'rb') as f:
    mycsv = csv.reader(f)
    mycsv = list(mycsv)
    text = mycsv[line_number][1]

Can Mysql Split a column?

Here is another variant I posted on related question. The REGEX check to see if you are out of bounds is useful, so for a table column you would put it in the where clause.

SET @Array = 'one,two,three,four';
SET @ArrayIndex = 2;
    WHEN @Array REGEXP CONCAT('((,).*){',@ArrayIndex,'}') 
    THEN SUBSTRING_INDEX(SUBSTRING_INDEX(@Array,',',@ArrayIndex+1),',',-1) 
END AS Result;
  • SUBSTRING_INDEX(string, delim, n) returns the first n
  • SUBSTRING_INDEX(string, delim, -1) returns the last only
  • REGEXP '((delim).*){n}' checks if there are n delimiters (i.e. you are in bounds)

Serializing to JSON in jQuery

If you don't want to use external libraries there is .toSource() native JavaScript method, but it's not perfectly cross-browser.

Is there a regular expression to detect a valid regular expression?

Though it is perfectly possible to use a recursive regex as MizardX has posted, for this kind of things it is much more useful a parser. Regexes were originally intended to be used with regular languages, being recursive or having balancing groups is just a patch.

The language that defines valid regexes is actually a context free grammar, and you should use an appropriate parser for handling it. Here is an example for a university project for parsing simple regexes (without most constructs). It uses JavaCC. And yes, comments are in Spanish, though method names are pretty self-explanatory.

    " "
|   "\r"
|   "\t"
|   "\n"
    < DIGITO: ["0" - "9"] >
|   < MAYUSCULA: ["A" - "Z"] >
|   < MINUSCULA: ["a" - "z"] >
|   < LAMBDA: "LAMBDA" >
|   < VACIO: "VACIO" >

IRegularExpression Expression() :
    IRegularExpression r; 
    r=Alternation() { return r; }

// Matchea disyunciones: ER | ER
IRegularExpression Alternation() :
    IRegularExpression r1 = null, r2 = null; 
    r1=Concatenation() ( "|" r2=Alternation() )?
        if (r2 == null) {
            return r1;
        } else {
            return createAlternation(r1,r2);

// Matchea concatenaciones: ER.ER
IRegularExpression Concatenation() :
    IRegularExpression r1 = null, r2 = null; 
    r1=Repetition() ( "." r2=Repetition() { r1 = createConcatenation(r1,r2); } )*
    { return r1; }

// Matchea repeticiones: ER*
IRegularExpression Repetition() :
    IRegularExpression r; 
    r=Atom() ( "*" { r = createRepetition(r); } )*
    { return r; }

// Matchea regex atomicas: (ER), Terminal, Vacio, Lambda
IRegularExpression Atom() :
    String t;
    IRegularExpression r;
    ( "(" r=Expression() ")" {return r;}) 
    | t=Terminal() { return createTerminal(t); }
    | <LAMBDA> { return createLambda(); }
    | <VACIO> { return createEmpty(); }

// Matchea un terminal (digito o minuscula) y devuelve su valor
String Terminal() :
    Token t;
    ( t=<DIGITO> | t=<MINUSCULA> ) { return t.image; }

Finding the average of a list

I want to add just another approach

import itertools,operator
list(itertools.accumulate(l,operator.add)).pop(-1) / len(l)

PHP Notice: Undefined offset: 1 with array when reading data

I just recently had this issue and I didn't even believe it was my mistype:

Array("Semester has been set as active!", true)
Array("Failed to set semester as active!". false)

And actually it was! I just accidentally typed "." rather than ","...

What is [Serializable] and when should I use it?

What is it?

When you create an object in a .Net framework application, you don't need to think about how the data is stored in memory. Because the .Net Framework takes care of that for you. However, if you want to store the contents of an object to a file, send an object to another process or transmit it across the network, you do have to think about how the object is represented because you will need to convert to a different format. This conversion is called SERIALIZATION.

Uses for Serialization

Serialization allows the developer to save the state of an object and recreate it as needed, providing storage of objects as well as data exchange. Through serialization, a developer can perform actions like sending the object to a remote application by means of a Web Service, passing an object from one domain to another, passing an object through a firewall as an XML string, or maintaining security or user-specific information across applications.

Apply SerializableAttribute to a type to indicate that instances of this type can be serialized. Apply the SerializableAttribute even if the class also implements the ISerializable interface to control the serialization process.

All the public and private fields in a type that are marked by the SerializableAttribute are serialized by default, unless the type implements the ISerializable interface to override the serialization process. The default serialization process excludes fields that are marked with NonSerializedAttribute. If a field of a serializable type contains a pointer, a handle, or some other data structure that is specific to a particular environment, and cannot be meaningfully reconstituted in a different environment, then you might want to apply NonSerializedAttribute to that field.

See MSDN for more details.

Edit 1

Any reason to not mark something as serializable

When transferring or saving data, you need to send or save only the required data. So there will be less transfer delays and storage issues. So you can opt out unnecessary chunk of data when serializing.

A cycle was detected in the build path of project xxx - Build Path Problem

This could happen when you have several projects that include each other in JAR form. What I did was remove all libraries and project dependencies on buildpath, for all projects. Then, one at a time, I added the project dependencies on the Project Tab, but only the ones needed. This is because you can add a project which in turn has itself referenced or another project which is referencing some other project with this self-referencing issue.

This resolved my issue.

Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX AVX2

If you use pip version of tensorflow, it means it's already compiled and you are just installing it. Basically you install tensorflow-gpu, but when you download it from repository and trying to build, you should build it with CPU AVX support. If you ignore it, you will get the warning every time when you run on cpu.

CSS: fixed position on x-axis but not y?

Updated the script to check the start position:

function float_horizontal_scroll(id) {
var el = jQuery(id);
var isLeft = el.css('left') !== 'auto';
var start =((isLeft ? el.css('left') : el.css('right')).replace("px", ""));
jQuery(window).scroll(function () {
    var leftScroll = jQuery(this).scrollLeft();
    if (isLeft)
        el.css({ 'left': (start + leftScroll) + 'px' });
        el.css({ 'right': (start - leftScroll) + 'px' });


How to disable clicking inside div

How to disable clicking another div click until first one popup div close

Image of the example

 <p class="btn1">One</p>
 <div id="box1" class="popup">
 Test Popup Box One
 <span class="close">X</span>

 <!-- Two -->
 <p class="btn2">Two</p>
 <div id="box2" class="popup">
 Test Popup Box Two
 <span class="close">X</span>

.disabledbutton {
 pointer-events: none;

.close {
cursor: pointer;



Sending email from Azure

I would never recommend SendGrid. I took up their free account offer and never managed to send a single email - all got blocked - I spent days trying to resolve it. When I enquired why they got blocked, they told me that free accounts share an ip address and if any account abuses that ip by sending spam - then everyone on the shared ip address gets blocked - totally useless. Also if you use them - do not store your email key in a git public repository as anyone can read the key from there (using a crawler) and use your chargeable account to send bulk emails.

A free email service which I've been using reliably with an Azure website is to use my Gmail (Google mail) account. That account has an option for using it with applications - once you enable that, then email can be sent from your azure website. Pasting in sample send code as the port to use (587) is not obvious.

  public static void SendMail(MailMessage Message)
        SmtpClient client = new SmtpClient();
        client.Host = EnvironmentSecret.Instance.SmtpHost; //
        client.Port = 587;
        client.UseDefaultCredentials = false;
        client.DeliveryMethod = SmtpDeliveryMethod.Network;
        client.EnableSsl = true;
        client.Credentials = new NetworkCredential(

How to get a variable type in Typescript?

I have checked a variable if it is a boolean or not as below


Similarly we have


and so on.

Compute row average in pandas

You can specify a new column. You also need to compute the mean along the rows, so use axis=1.

df['mean'] = df.mean(axis=1)
>>> df
       Y1961      Y1962      Y1963      Y1964      Y1965 Region       mean
0  82.567307  83.104757  83.183700  83.030338  82.831958     US  82.943612
1   2.699372   2.610110   2.587919   2.696451   2.846247     US   2.688020
2  14.131355  13.690028  13.599516  13.649176  13.649046     US  13.743824
3   0.048589   0.046982   0.046583   0.046225   0.051750     US   0.048026
4   0.553377   0.548123   0.582282   0.577811   0.620999     US   0.576518

How do I know which version of Javascript I'm using?

All of todays browsers use at least version 1.5:

Concerning your tutorial site, the information there seems to be extremely outdated, I beg you to head over to MDC and read their Guide:

You may still want to watch out for features which require version 1.6 or above, as this might give Internet Explorer some troubles.

Bundling data files with PyInstaller (--onefile)

Using the excellent answer from Max and This post about adding extra data files like images or sound & my own research/testing, I've figured out what I believe is the easiest way to add such files.

If you would like to see a live example, my repository is here on GitHub.

Note: this is for compiling using the --onefile or -F command with pyinstaller.

My environment is as follows.

Solving the problem in 2 steps

To solve the issue we need to specifically tell Pyinstaller that we have extra files that need to be "bundled" with the application.

We also need to be using a 'relative' path, so the application can run properly when it's running as a Python Script or a Frozen EXE.

With that being said we need a function that allows us to have relative paths. Using the function that Max Posted we can easily solve the relative pathing.

def img_resource_path(relative_path):
    """ Get absolute path to resource, works for dev and for PyInstaller """
        # PyInstaller creates a temp folder and stores path in _MEIPASS
        base_path = sys._MEIPASS
    except Exception:
        base_path = os.path.abspath(".")

    return os.path.join(base_path, relative_path)

We would use the above function like this so the application icon shows up when the app is running as either a Script OR Frozen EXE.

icon_path = img_resource_path("app/img/app_icon.ico")

The next step is that we need to instruct Pyinstaller on where to find the extra files when it's compiling so that when the application is run, they get created in the temp directory.

We can solve this issue two ways as shown in the documentation, but I personally prefer managing my own .spec file so that's how we're going to do it.

First, you must already have a .spec file. In my case, I was able to create what I needed by running pyinstaller with extra args, you can find extra args here. Because of this, my spec file may look a little different than yours but I'm posting all of it for reference after I explain the important bits.

added_files is essentially a List containing Tuple's, in my case I'm only wanting to add a SINGLE image, but you can add multiple ico's, png's or jpg's using ('app/img/*.ico', 'app/img') You may also create another tuple like soadded_files = [ (), (), ()] to have multiple imports

The first part of the tuple defines what file or what type of file's you would like to add as well as where to find them. Think of this as CTRL+C

The second part of the tuple tells Pyinstaller, to make the path 'app/img/' and place the files in that directory RELATIVE to whatever temp directory gets created when you run the .exe. Think of this as CTRL+V

Under a = Analysis([main..., I've set datas=added_files, originally it used to be datas=[] but we want out the list of imports to be, well, imported so we pass in our custom imports.

You don't need to do this unless you want a specific icon for the EXE, at the bottom of the spec file I'm telling Pyinstaller to set my application icon for the exe with the option icon='app\\img\\app_icon.ico'.

added_files = [
a = Analysis([''],
             pathex=['D:\\Github Repos\\Processes-Killer\\Process Killer'],
pyz = PYZ(a.pure, a.zipped_data,
exe = EXE(pyz,
          name='Process Killer',
          console=True , uac_admin=True, icon='app\\img\\app_icon.ico')

Compiling to EXE

I'm very lazy; I don't like typing things more than I have to. I've created a .bat file that I can just click. You don't have to do this, this code will run in a command prompt shell just fine without it.

Since the .spec file contains all of our compiling settings & args (aka options) we just have to give that .spec file to Pyinstaller.

pyinstaller.exe "Process Killer.spec"

Binding ItemsSource of a ComboBoxColumn in WPF DataGrid

Pls, check if DataGridComboBoxColumn xaml below would work for you:

    SelectedValueBinding="{Binding CompanyID}" 

        <Style TargetType="{x:Type ComboBox}">
            <Setter Property="ItemsSource" Value="{Binding Path=DataContext.CompanyItems, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
        <Style TargetType="{x:Type ComboBox}">
            <Setter Property="ItemsSource" Value="{Binding Path=DataContext.CompanyItems, RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />

Here you can find another solution for the problem you're facing: Using combo boxes with the WPF DataGrid

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

It Super Easy,

enter image description here

Other way,

in terminal go your FOLDER,


xxx\FOLDER_NAME> ng generate component plainsight

Bonus point if you lasy like me to copy path(Visual studio code),

enter image description here

Does GPS require Internet?

I've found out that GPS does not need Internet, BUT of course if you need to download maps, you will need a data connection or wifi.

Posting raw image data as multipart/form-data in curl

In case anyone had the same problem: check this as @PravinS suggested. I used the exact same code as shown there and it worked for me perfectly.

This is the relevant part of the server code that helped:

if (isset($_POST['btnUpload']))
$url = "URL_PATH of upload.php"; // e.g. http://localhost/myuploader/upload.php // request URL
$filename = $_FILES['file']['name'];
$filedata = $_FILES['file']['tmp_name'];
$filesize = $_FILES['file']['size'];
if ($filedata != '')
    $headers = array("Content-Type:multipart/form-data"); // cURL headers for file uploading
    $postfields = array("filedata" => "@$filedata", "filename" => $filename);
    $ch = curl_init();
    $options = array(
        CURLOPT_URL => $url,
        CURLOPT_HEADER => true,
        CURLOPT_POST => 1,
        CURLOPT_HTTPHEADER => $headers,
        CURLOPT_POSTFIELDS => $postfields,
        CURLOPT_INFILESIZE => $filesize,
    ); // cURL options
    curl_setopt_array($ch, $options);
        $info = curl_getinfo($ch);
        if ($info['http_code'] == 200)
            $errmsg = "File uploaded successfully";
        $errmsg = curl_error($ch);
    $errmsg = "Please select the file";

html form should look something like:

<form action="uploadpost.php" method="post" name="frmUpload" enctype="multipart/form-data">
  <td align="center">:</td>
  <td><input name="file" type="file" id="file"/></td>
  <td align="center">&nbsp;</td>
  <td><input name="btnUpload" type="submit" value="Upload" /></td>

How to modify PATH for Homebrew?

open your /etc/paths file, put /usr/local/bin on top of /usr/bin

$ sudo vi /etc/paths

and Restart the terminal, @mmel

How to use KeyListener

The class which implements KeyListener interface becomes our custom key event listener. This listener can not directly listen the key events. It can only listen the key events through intermediate objects such as JFrame. So

  1. Make one Key listener class as

    class MyListener implements KeyListener{
       // override all the methods of KeyListener interface.
  2. Now our class MyKeyListener is ready to listen the key events. But it can not directly do so.

  3. Create any object like JFrame object through which MyListener can listen the key events. for that you need to add MyListener object to the JFrame object.

    JFrame f=new JFrame();
    f.addKeyListener(new MyKeyListener);

How to set full calendar to a specific start date when it's initialized for the 1st time?

You can just pass a Date object:
For current date:

    defaultDate: new Date()

For specific date '2016-05-20':

    defaultDate: new Date(2016, 4, 20)

How to 'bulk update' with Django?

If you want to set the same value on a collection of rows, you can use the update() method combined with any query term to update all rows in one query:

some_list = ModelClass.objects.filter(some condition).values('id')

If you want to update a collection of rows with different values depending on some condition, you can in best case batch the updates according to values. Let's say you have 1000 rows where you want to set a column to one of X values, then you could prepare the batches beforehand and then only run X update-queries (each essentially having the form of the first example above) + the initial SELECT-query.

If every row requires a unique value there is no way to avoid one query per update. Perhaps look into other architectures like CQRS/Event sourcing if you need performance in this latter case.

Convert string to Color in C#

Since the OP mentioned in a comment that he's using Microsoft.Xna.Framework.Graphics.Color rather than System.Drawing.Color you can first create a System.Drawing.Color then convert it to a Microsoft.Xna.Framework.Graphics.Color

public static Color FromName(string colorName)
    System.Drawing.Color systemColor = System.Drawing.Color.FromName(colorName);   
    return new Color(systemColor.R, systemColor.G, systemColor.B, systemColor.A); //Here Color is Microsoft.Xna.Framework.Graphics.Color

Difference between "move" and "li" in MIPS assembly language

The move instruction copies a value from one register to another. The li instruction loads a specific numeric value into that register.

For the specific case of zero, you can use either the constant zero or the zero register to get that:

move $s0, $zero
li   $s0, 0

There's no register that generates a value other than zero, though, so you'd have to use li if you wanted some other number, like:

li $s0, 12345678

random.seed(): What does it do?

Pseudo-random number generators work by performing some operation on a value. Generally this value is the previous number generated by the generator. However, the first time you use the generator, there is no previous value.

Seeding a pseudo-random number generator gives it its first "previous" value. Each seed value will correspond to a sequence of generated values for a given random number generator. That is, if you provide the same seed twice, you get the same sequence of numbers twice.

Generally, you want to seed your random number generator with some value that will change each execution of the program. For instance, the current time is a frequently-used seed. The reason why this doesn't happen automatically is so that if you want, you can provide a specific seed to get a known sequence of numbers.

npm check and update package if needed

npm outdated will identify packages that should be updated, and npm update <package name> can be used to update each package. But prior to [email protected], npm update <package name> will not update the versions in your package.json which is an issue.

The best workflow is to:

  1. Identify out of date packages
  2. Update the versions in your package.json
  3. Run npm update to install the latest versions of each package

Check out npm-check-updates to help with this workflow.

  • Install npm-check-updates
  • Run npm-check-updates to list what packages are out of date (basically the same thing as running npm outdated)
  • Run npm-check-updates -u to update all the versions in your package.json (this is the magic sauce)
  • Run npm update as usual to install the new versions of your packages based on the updated package.json

How to get domain root url in Laravel 4?

This is for Laravel 5.1 and I am not sure does it work for earlier versions but if somebody search on Google and lands here it might be handy in middleware handle function gets $request parameter:


outside of middleware handle method you can access it by helper function request()


How to fix Git error: object file is empty?

In my case, it wasn't important for me to keep the local commit history. So if that applies to you too, you can do this as a quick alternative to the solutions above:

You basically just replace the corrupted .git/ directory with a clean one.

Lets presume the following directory for your project with the corrupted git: projects/corrupt_git/

  1. cp projects/corrupt_git projects/backup - (optional) make a backup
  2. git clone [repo URL] projects/clean_git - so that you get projects/clean_git
  3. rm -rf corrupt_git/.git/ - remove the corrupted .git folder
  4. mv clean_git/.git/ corrupt_git/ - move clean git to corrupt_git/.git
  5. git status in projects/corrupt_git - to make sure it worked

Associating enums with strings in C#

My first question - Do you have access to the Database itself? This should be normalized in the database, ideally, otherwise, any solution is going to be prone to error. In my experience, data fields full of "OEM" and "CMB" tend to wind up having things like "oem " and other 'crap data' mixed in over time.... If you can normalize it, you could use the key in the table containing the elements as your Enum, and you're done, with a much cleaner structure.

If that's not available, I'd make your Enum, and make a class to parse your string into the Enum for you. This would at least give you some flexibility in handling non-standard entries and much more flexibility for trapping or handling errors than doing any of the workarounds using Enum.Parse/Reflection/etc. A dictionary would work, but could break down if you ever have case issues, etc.

I'd recommend writing a class so you can do:

// I renamed this to GroupType, since it sounds like each element has a single type...
GroupType theType = GroupTypeParser.GetGroupType(theDBString);

This preserves most of your readability without having to change the DB.

How is attr_accessible used in Rails 4?

Rails 4 now uses strong parameters.

Protecting attributes is now done in the controller. This is an example:

class PeopleController < ApplicationController
  def create


  def person_params
    params.require(:person).permit(:name, :age)

No need to set attr_accessible in the model anymore.

Dealing with accepts_nested_attributes_for

In order to use accepts_nested_attribute_for with strong parameters, you will need to specify which nested attributes should be whitelisted.

class Person
  has_many :pets
  accepts_nested_attributes_for :pets

class PeopleController < ApplicationController
  def create

  # ...


  def person_params
    params.require(:person).permit(:name, :age, pets_attributes: [:name, :category])

Keywords are self-explanatory, but just in case, you can find more information about strong parameters in the Rails Action Controller guide.

Note: If you still want to use attr_accessible, you need to add protected_attributes to your Gemfile. Otherwise, you will be faced with a RuntimeError.

JavaScript dictionary with names

An object technically is a dictionary.

var myMappings = {
    mykey1: 'myValue',
    mykey2: 'myValue'

var myVal = myMappings['myKey1'];

alert(myVal); // myValue

You can even loop through one.

for(var key in myMappings) {
    var myVal = myMappings[key];

There is no reason whatsoever to reinvent the wheel. And of course, assignment goes like:

myMappings['mykey3'] = 'my value';

And ContainsKey:

if (myMappings.hasOwnProperty('myKey3')) {
    alert('key already exists!');

I suggest you follow this:

Removing duplicate elements from an array in Swift

var numbers = [1,2,3,4,5,10,10, 12, 12, 6,6,6,7,8,8, 8, 8, 8 , 7 , 1 , 1, 2 , 9]

var newArr : [Int] = []
for n in numbers {
    if !newArr.contains(n) {

output - [1, 2, 3, 4, 5, 10, 12, 6, 7, 8, 9]

The above solution maintains order but very slow as .contains iterates again and again. Thus use the ordered set.

This will print the ordered array.

Array(NSOrderedSet.init(array: numbers))

output - [1, 2, 3, 4, 5, 10, 12, 6, 7, 8, 9]

This Will Print an unordered array.

let uniqueUnordered = Array(Set(numbers))

output - [4, 2, 1, 9, 10, 3, 5, 6, 8, 12, 7]

AngularJS performs an OPTIONS HTTP request for a cross-origin resource

If you are using a nodeJS server, you can use this library, it worked fine for me

var express = require('express')
  , cors = require('cors')
  , app = express();


and after you can do an npm update.

Having the output of a console application in Visual Studio instead of the console

If you need output from Console.WriteLine, and the Redirect All Output Window Text to the Immediate Window does not function and you need to know the output of Tests from the Integrated Test Explorer, using NUnit.Framework our problem is already solved at VS 2017:

Example taken from C# In Depth by Jon Skeet: Example taken from C# In Depth by Jon Skeet This produce this output at Text Explorer: Task Explorer

When we click on Blue Output, under Elapsed Time, at right, and it produces this: Standard Output

Standard Output is our desired Output, produced by Console.WriteLine.

It functions for Console and for Windows Form Applications at VS 2017, but only for Output generated for Test Explorer at Debug or Run; anyway, this is my main need of Console.WriteLine output.

How to clear all input fields in a specific div with jQuery?

Change this:

 <div class=fetch_results>

To this:

 <div id="fetch_results">

Then the following should work:

$("#fetch_results input").each(function() {
      this.value = "";

What is the difference between a 'closure' and a 'lambda'?

There is a lot of confusion around lambdas and closures, even in the answers to this StackOverflow question here. Instead of asking random programmers who learned about closures from practice with certain programming languages or other clueless programmers, take a journey to the source (where it all began). And since lambdas and closures come from Lambda Calculus invented by Alonzo Church back in the '30s before first electronic computers even existed, this is the source I'm talking about.

Lambda Calculus is the simplest programming language in the world. The only things you can do in it:?

  • APPLICATION: Applying one expression to another, denoted f x.
    (Think of it as a function call, where f is the function and x is its only parameter)
  • ABSTRACTION: Binds a symbol occurring in an expression to mark that this symbol is just a "slot", a blank box waiting to be filled with value, a "variable" as it were. It is done by prepending a Greek letter ? (lambda), then the symbolic name (e.g. x), then a dot . before the expression. This then converts the expression into a function expecting one parameter.
    For example: ?x.x+2 takes the expression x+2 and tells that the symbol x in this expression is a bound variable – it can be substituted with a value you supply as a parameter.
    Note that the function defined this way is anonymous – it doesn't have a name, so you can't refer to it yet, but you can immediately call it (remember application?) by supplying it the parameter it is waiting for, like this: (?x.x+2) 7. Then the expression (in this case a literal value) 7 is substituted as x in the subexpression x+2 of the applied lambda, so you get 7+2, which then reduces to 9 by common arithmetics rules.

So we've solved one of the mysteries:
lambda is the anonymous function from the example above, ?x.x+2.

In different programming languages, the syntax for functional abstraction (lambda) may differ. For example, in JavaScript it looks like this:

function(x) { return x+2; }

and you can immediately apply it to some parameter like this:

(function(x) { return x+2; })(7)

or you can store this anonymous function (lambda) into some variable:

var f = function(x) { return x+2; }

which effectively gives it a name f, allowing you to refer to it and call it multiple times later, e.g.:

alert(  f(7) + f(10)  );   // should print 21 in the message box

But you didn't have to name it. You could call it immediately:

alert(  function(x) { return x+2; } (7)  );  // should print 9 in the message box

In LISP, lambdas are made like this:

(lambda (x) (+ x 2))

and you can call such a lambda by applying it immediately to a parameter:

(  (lambda (x) (+ x 2))  7  )

OK, now it's time to solve the other mystery: what is a closure. In order to do that, let's talk about symbols (variables) in lambda expressions.

As I said, what the lambda abstraction does is binding a symbol in its subexpression, so that it becomes a substitutible parameter. Such a symbol is called bound. But what if there are other symbols in the expression? For example: ?x.x/y+2. In this expression, the symbol x is bound by the lambda abstraction ?x. preceding it. But the other symbol, y, is not bound – it is free. We don't know what it is and where it comes from, so we don't know what it means and what value it represents, and therefore we cannot evaluate that expression until we figure out what y means.

In fact, the same goes with the other two symbols, 2 and +. It's just that we are so familiar with these two symbols that we usually forget that the computer doesn't know them and we need to tell it what they mean by defining them somewhere, e.g. in a library or the language itself.

You can think of the free symbols as defined somewhere else, outside the expression, in its "surrounding context", which is called its environment. The environment might be a bigger expression that this expression is a part of (as Qui-Gon Jinn said: "There's always a bigger fish" ;) ), or in some library, or in the language itself (as a primitive).

This lets us divide lambda expressions into two categories:

  • CLOSED expressions: every symbol that occurs in these expressions is bound by some lambda abstraction. In other words, they are self-contained; they don't require any surrounding context to be evaluated. They are also called combinators.
  • OPEN expressions: some symbols in these expressions are not bound – that is, some of the symbols occurring in them are free and they require some external information, and thus they cannot be evaluated until you supply the definitions of these symbols.

You can CLOSE an open lambda expression by supplying the environment, which defines all these free symbols by binding them to some values (which may be numbers, strings, anonymous functions aka lambdas, whatever…).

And here comes the closure part:
The closure of a lambda expression is this particular set of symbols defined in the outer context (environment) that give values to the free symbols in this expression, making them non-free anymore. It turns an open lambda expression, which still contains some "undefined" free symbols, into a closed one, which doesn't have any free symbols anymore.

For example, if you have the following lambda expression: ?x.x/y+2, the symbol x is bound, while the symbol y is free, therefore the expression is open and cannot be evaluated unless you say what y means (and the same with + and 2, which are also free). But suppose that you also have an environment like this:

{  y: 3,
+: [built-in addition],
2: [built-in number],
q: 42,
w: 5  }

This environment supplies definitions for all the "undefined" (free) symbols from our lambda expression (y, +, 2), and several extra symbols (q, w). The symbols that we need to be defined are this subset of the environment:

{  y: 3,
+: [built-in addition],
2: [built-in number]  }

and this is precisely the closure of our lambda expression :>

In other words, it closes an open lambda expression. This is where the name closure came from in the first place, and this is why so many people's answers in this thread are not quite correct :P

So why are they mistaken? Why do so many of them say that closures are some data structures in memory, or some features of the languages they use, or why do they confuse closures with lambdas? :P

Well, the corporate marketoids of Sun/Oracle, Microsoft, Google etc. are to blame, because that's what they called these constructs in their languages (Java, C#, Go etc.). They often call "closures" what are supposed to be just lambdas. Or they call "closures" a particular technique they used to implement lexical scoping, that is, the fact that a function can access the variables that were defined in its outer scope at the time of its definition. They often say that the function "encloses" these variables, that is, captures them into some data structure to save them from being destroyed after the outer function finishes executing. But this is just made-up post factum "folklore etymology" and marketing, which only makes things more confusing, because every language vendor uses its own terminology.

And it's even worse because of the fact that there's always a bit of truth in what they say, which does not allow you to easily dismiss it as false :P Let me explain:

If you want to implement a language that uses lambdas as first-class citizens, you need to allow them to use symbols defined in their surrounding context (that is, to use free variables in your lambdas). And these symbols must be there even when the surrounding function returns. The problem is that these symbols are bound to some local storage of the function (usually on the call stack), which won't be there anymore when the function returns. Therefore, in order for a lambda to work the way you expect, you need to somehow "capture" all these free variables from its outer context and save them for later, even when the outer context will be gone. That is, you need to find the closure of your lambda (all these external variables it uses) and store it somewhere else (either by making a copy, or by preparing space for them upfront, somewhere else than on the stack). The actual method you use to achieve this goal is an "implementation detail" of your language. What's important here is the closure, which is the set of free variables from the environment of your lambda that need to be saved somewhere.

It didn't took too long for people to start calling the actual data structure they use in their language's implementations to implement closure as the "closure" itself. The structure usually looks something like this:

Closure {
   [pointer to the lambda function's machine code],
   [pointer to the lambda function's environment]

and these data structures are being passed around as parameters to other functions, returned from functions, and stored in variables, to represent lambdas, and allowing them to access their enclosing environment as well as the machine code to run in that context. But it's just a way (one of many) to implement closure, not the closure itself.

As I explained above, the closure of a lambda expression is the subset of definitions in its environment that give values to the free variables contained in that lambda expression, effectively closing the expression (turning an open lambda expression, which cannot be evaluated yet, into a closed lambda expression, which can then be evaluated, since all the symbols contained in it are now defined).

Anything else is just a "cargo cult" and "voo-doo magic" of programmers and language vendors unaware of the real roots of these notions.

I hope that answers your questions. But if you had any follow-up questions, feel free to ask them in the comments, and I'll try to explain it better.

querying WHERE condition to character length?

Sorry, I wasn't sure which SQL platform you're talking about:


$query = ("SELECT * FROM $db WHERE conditions AND LENGTH(col_name) = 3");


$query = ("SELECT * FROM $db WHERE conditions AND LEN(col_name) = 3");

The LENGTH() (MySQL) or LEN() (MSSQL) function will return the length of a string in a column that you can use as a condition in your WHERE clause.


I know this is really old but thought I'd expand my answer because, as Paulo Bueno rightly pointed out, you're most likely wanting the number of characters as opposed to the number of bytes. Thanks Paulo.

So, for MySQL there's the CHAR_LENGTH(). The following example highlights the difference between LENGTH() an CHAR_LENGTH():

    word VARCHAR(100)
) ENGINE INNODB DEFAULT CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci;

INSERT INTO words(word) VALUES('??'), ('happy'), ('hayir');

SELECT word, LENGTH(word) as num_bytes, CHAR_LENGTH(word) AS num_characters FROM words;

| word   | num_bytes | num_characters |
| ??    |         6 |              2 |
| happy  |         5 |              5 |
| hayir  |         6 |              5 |

Be careful if you're dealing with multi-byte characters.

What is time_t ultimately a typedef to?

time_t is of type long int on 64 bit machines, else it is long long int.

You could verify this in these header files:

time.h: /usr/include
types.h and typesizes.h: /usr/include/x86_64-linux-gnu/bits

(The statements below are not one after another. They could be found in the resp. header file using Ctrl+f search.)

1)In time.h

typedef __time_t time_t;

2)In types.h

# define __STD_TYPE     typedef  
__STD_TYPE __TIME_T_TYPE __time_t;  

3)In typesizes.h

#define __TIME_T_TYPE       __SYSCALL_SLONG_TYPE  
#if defined __x86_64__ && defined __ILP32__  

4) Again in types.h

#define __SLONGWORD_TYPE    long int
#if __WORDSIZE == 32
# define __SQUAD_TYPE       __quad_t
#elif __WORDSIZE == 64
# define __SQUAD_TYPE       long int  

#if __WORDSIZE == 64
typedef long int __quad_t;  
__extension__ typedef long long int __quad_t;

Installing Numpy on 64bit Windows 7 with Python 2.7.3

You may also try this, anaconda

But you need to modify your environment variable PATH, so that the anaconda folder is before the original Python folder.

Jmeter - Run .jmx file through command line and get the summary report in a excel

You can run JMeter from the command line using the -n parameter for 'Non-GUI' and the -t parameter for the test plan file.

    jmeter -n -t "PATHTOJMXFILE"        

If you want to further customize the command line experience, I would direct you to the 'Getting Started' section of their documentation.

replace String with another in java

Another suggestion, Let's say you have two same words in the String

String s1 = "who is my brother, who is your brother"; // I don't mind the meaning of the sentence.

replace function will change every string is given in the first parameter to the second parameter

System.out.println(s1.replace("brother", "sister")); // who is my sister, who is your sister

and you can use also replaceAll method for the same result

System.out.println(s1.replace("brother", "sister")); // who is my sister, who is your sister

if you want to change just the first string which is positioned earlier,

System.out.println(s1.replaceFirst("brother", "sister")); // whos is my sister, who is your brother.

What does the "+=" operator do in Java?

As many people have already pointed out, it's the XOR operator. Many people have also already pointed out that if you want exponentiation then you need to use Math.pow.

But I think it's also useful to note that ^ is just one of a family of operators that are collectively known as bitwise operators:

Operator    Name         Example     Result  Description
a & b       and          3 & 5       1       1 if both bits are 1.
a | b       or           3 | 5       7       1 if either bit is 1.
a ^ b       xor          3 ^ 5       6       1 if both bits are different.
~a          not          ~3          -4      Inverts the bits.
n << p      left shift   3 << 2      12      Shifts the bits of n left p positions. Zero bits are shifted into the low-order positions.
n >> p      right shift  5 >> 2      1       Shifts the bits of n right p positions. If n is a 2's complement signed number, the sign bit is shifted into the high-order positions.
n >>> p     right shift  -4 >>> 28   15      Shifts the bits of n right p positions. Zeros are shifted into the high-order positions.

From here.

These operators can come in handy when you need to read and write to integers where the individual bits should be interpreted as flags, or when a specific range of bits in an integer have a special meaning and you want to extract only those. You can do a lot of every day programming without ever needing to use these operators, but if you ever have to work with data at the bit level, a good knowledge of these operators is invaluable.

Two Decimal places using c#

The best approach if you want to ALWAYS show two decimal places (even if your number only has one decimal place) is to use


ExecuteReader: Connection property has not been initialized

As mentioned you should assign the connection and you should preferably also use sql parameters instead, so your command assignment would read:

    // 3. Pass the connection to a command object
    SqlCommand cmd=new SqlCommand ("insert into time(project,iteration) values (@project, @iteration)", conn); // ", conn)" added
    cmd.Parameters.Add("project", System.Data.SqlDbType.NVarChar).Value = this.name1.SelectedValue;
    cmd.Parameters.Add("iteration", System.Data.SqlDbType.NVarChar).Value = this.name1.SelectedValue;

    // 4. Use the connection

By using parameters you avoid SQL injection and other problematic typos (project names like "myproject's" is an example).

ArrayList vs List<> in C#

To add to the above points. Using ArrayList in 64bit operating system takes 2x memory than using in the 32bit operating system. Meanwhile, generic list List<T> will use much low memory than the ArrayList.

for example if we use a ArrayList of 19MB in 32-bit it would take 39MB in the 64-bit. But if you have a generic list List<int> of 8MB in 32-bit it would take only 8.1MB in 64-bit, which is a whooping 481% difference when compared to ArrayList.

Source: ArrayList’s vs. generic List for primitive types and 64-bits

Python Write bytes to file

If you want to write bytes then you should open the file in binary mode.

f = open('/tmp/output', 'wb')

Downloading an entire S3 bucket?

  1. Windows User need to download S3EXPLORER from this link which also has installation instructions :-

  2. Then provide you AWS credentials like secretkey, accesskey and region to the s3explorer, this link contains configuration instruction for s3explorer:Copy Paste Link in brower:

  3. Now your all s3 buckets would be visible on left panel of s3explorer.

  4. Simply select the bucket, and click on Buckets menu on top left corner, then select Download all files to option from the menu. Below is the screenshot for the same:

Bucket Selection Screen

  1. Then browse a folder to download the bucket at a particular place

  2. Click on OK and your download would begin.

Remove duplicates from an array of objects in JavaScript

This is simple way how to remove duplicity from array of objects.

I work with data a lot and this is useful for me.

const data = [{name: 'AAA'}, {name: 'AAA'}, {name: 'BBB'}, {name: 'AAA'}];
function removeDuplicity(datas){
    return datas.filter((item, index,arr)=>{
    const c =>;
    return  index === c.indexOf(


will print into console :

[[object Object] {
name: "AAA"
}, [object Object] {
name: "BBB"

How to set cookie in node js using express framework?

Not exactly answering your question, but I came across your question, while looking for an answer to an issue that I had. Maybe it will help somebody else.

My issue was that cookies were set in server response, but were not saved by the browser.

The server response came back with cookies set:

Set-Cookie:my_cookie=HelloWorld; Path=/; Expires=Wed, 15 Mar 2017 15:59:59 GMT 

This is how I solved it.

I used fetch in the client-side code. If you do not specify credentials: 'include' in the fetch options, cookies are neither sent to server nor saved by the browser, even though the server response sets cookies.


var headers = new Headers();
headers.append('Content-Type', 'application/json');
headers.append('Accept', 'application/json');

return fetch('/your/server_endpoint', {
    method: 'POST',
    mode: 'same-origin',
    redirect: 'follow',
    credentials: 'include', // Don't forget to specify this if you need cookies
    headers: headers,
    body: JSON.stringify({
        first_name: 'John',
        last_name: 'Doe'

I hope this helps somebody.

How to remove a package in sublime text 2

Just wanted to add, that after you remove the package in question you might also need to check to see if it's listed in the list of packages in the following area and manually remove its listing:

Preferences>Package Settings>Package Control>Settings - User

    "auto_upgrade_last_run": null,
        "Package Control",

In my instance, my trial period for "Sublimerge" had run out and I would get a popup every time I would start Sublime Text 2 saying:

"The package specified, Sublimerge, is not available"

I would have to close the event window out before being able to do anything in ST2.

But in my case, even after successfully removing the package through package control, I still received a event window popup message telling me "Sublimerge" wasn't available. This didn't make any sense as I had successfully removed the package.

It wasn't until I found this "auto_upgrade_last_run" file and manually removed the "Sublimerge" entry and saved my edit, did the message go away.

Cannot access mongodb through browser - It looks like you are trying to access MongoDB over HTTP on the native driver port

I am in ubuntu 14.04 and mongod is registered as an upstart service. The answers in this post sent me in the right direction. The only adaptation I had to do to make things work with the upstart service was to edit /etc/mongod.conf. Look for the lines that read:

# Enable the HTTP interface (Defaults to port 28017).
# httpinterface = true

Just remove the # in front of httpinterface and restart the mongod service:

sudo restart mongod

Note: You can also enable the rest interface by adding a line that reads rest=true right below the httpinterface line mentioned above.

Deep-Learning Nan loss reasons

If you're training for cross entropy, you want to add a small number like 1e-8 to your output probability.

Because log(0) is negative infinity, when your model trained enough the output distribution will be very skewed, for instance say I'm doing a 4 class output, in the beginning my probability looks like

0.25 0.25 0.25 0.25

but toward the end the probability will probably look like

1.0 0 0 0

And you take a cross entropy of this distribution everything will explode. The fix is to artifitially add a small number to all the terms to prevent this.

click() event is calling twice in jquery

I had the same problem, but you can try changing this code

.click(function () {

to this:

$("#link_button").unbind("click").click(function () {

For me, this code solved the problem. But take care not to accidentally include your script twice in your HTML page. I think that if you are doing these two things correctly, your code will work correctly. Thanks

How to hide TabPage from TabControl

I've used the same approach but the problem is that when tab page was removed from the tab control TabPages list, it is removed from the tab page Controls list also. And it is not disposed when form is disposed.

So if you have a lot of such "hidden" tab pages, you can get windows handle quota exceeded error and only application restart will fix it.

Angular, Http GET with parameter?

Having something like this:

let headers = new Headers();
headers.append('Content-Type', 'application/json');
let params = new URLSearchParams();
params.append("someParamKey", this.someParamValue)

this.http.get('http://localhost:63203/api/CallCenter/GetSupport', { headers: headers, search: params })

Of course, appending every param you need to params. It gives you a lot more flexibility than just using a URL string to pass params to the request.

EDIT(28.09.2017): As Al-Mothafar stated in a comment, search is deprecated as of Angular 4, so you should use params

EDIT(02.11.2017): If you are using the new HttpClient there are now HttpParams, which look and are used like this:

let params = new HttpParams().set("paramName",paramValue).set("paramName2", paramValue2); //Create new HttpParams

And then add the params to the request in, basically, the same way:

this.http.get(url, {headers: headers, params: params}); 
//No need to use .map(res => res.json()) anymore

More in the docs for HttpParams and HttpClient

Get specific objects from ArrayList when objects were added anonymously?

Given the use of List, there's no way to "lookup" a value without iterating through it...

For example...

Cave cave = new Cave();

// Loop adds several Parties to the cave's party list
cave.parties.add(new Party("FirstParty")); // all anonymously added
cave.parties.add(new Party("SecondParty"));
cave.parties.add(new Party("ThirdParty"));

for (Party p : cave.parties) {
    if ("SecondParty") {
        p.index = ...;

Now, this will take time. If the element you are looking for is at the end of the list, you will have to iterate to the end of the list before you find a match.

It might be better to use a Map of some kind...

So, if we update Cave to look like...

class Cave {
    Map<String, Party> parties = new HashMap<String, Party>(25);

We could do something like...

Cave cave = new Cave();

// Loop adds several Parties to the cave's party list
cave.parties.put("FirstParty", new Party("FirstParty")); // all anonymously added
cave.parties.put("SecondParty", new Party("SecondParty"));
cave.parties.put("ThirdParty", new Party("ThirdParty"));

if (cave.parties.containsKey("SecondParty")) {
    cave.parties.get("SecondParty").index = ...


Ultimately, this will all depend on what it is you want to achieve...

What is an undefined reference/unresolved external symbol error and how do I fix it?

This issue occurred for me by declaring the prototype of a function in a header file:

int createBackground(VertexArray rVA, IntRect arena);

But then defining the function elsewhere using a reference with the first parameter:

int createBackground(VertexArray& rVA, IntRect arena) {}

The fact that the prototype was not using a reference in the first parameter, while the definition was, was causing this issue. When I changed both to properly match either containing a reference or not containing a reference, the issue was fixed.


Excel - find cell with same value in another worksheet and enter the value to the left of it

Assuming employee numbers are in the first column and their names are in the second:

=VLOOKUP(A1, Sheet2!A:B, 2,false)

How to remove non-alphanumeric characters?



$string = preg_replace("/[\W_]+/u", '', $string);

It select all not A-Z, a-z, 0-9 and delete it.

See example here:

generate random string for div id

window.btoa(String.fromCharCode(...window.crypto.getRandomValues(new Uint8Array(5))))

Using characters except ASCII letters, digits, '_', '-' and '.' may cause compatibility problems, as they weren't allowed in HTML 4. Though this restriction has been lifted in HTML5, an ID should start with a letter for compatibility.

Count distinct values

I think this link is pretty good.

Sample output from that link:

mysql> SELECT cate_id,COUNT(DISTINCT(pub_lang)), ROUND(AVG(no_page),2)
    -> FROM book_mast
    -> GROUP BY cate_id;
| cate_id | COUNT(DISTINCT(pub_lang)) | ROUND(AVG(no_page),2) |
| CA001   |                         2 |                264.33 | 
| CA002   |                         1 |                433.33 | 
| CA003   |                         2 |                256.67 | 
| CA004   |                         3 |                246.67 | 
| CA005   |                         3 |                245.75 | 
5 rows in set (0.00 sec)

Add a reference column migration in Rails 4

Rails 4.x

When you already have users and uploads tables and wish to add a new relationship between them.

All you need to do is: just generate a migration using the following command:

rails g migration AddUserToUploads user:references

Which will create a migration file as:

class AddUserToUploads < ActiveRecord::Migration
  def change
    add_reference :uploads, :user, index: true

Then, run the migration using rake db:migrate. This migration will take care of adding a new column named user_id to uploads table (referencing id column in users table), PLUS it will also add an index on the new column.

UPDATE [For Rails 4.2]

Rails can’t be trusted to maintain referential integrity; relational databases come to our rescue here. What that means is that we can add foreign key constraints at the database level itself and ensure that database would reject any operation that violates this set referential integrity. As @infoget commented, Rails 4.2 ships with native support for foreign keys(referential integrity). It's not required but you might want to add foreign key(as it's very useful) to the reference that we created above.

To add foreign key to an existing reference, create a new migration to add a foreign key:

class AddForeignKeyToUploads < ActiveRecord::Migration
  def change
    add_foreign_key :uploads, :users

To create a completely brand new reference with a foreign key(in Rails 4.2), generate a migration using the following command:

rails g migration AddUserToUploads user:references

which will create a migration file as:

class AddUserToUploads < ActiveRecord::Migration
  def change
    add_reference :uploads, :user, index: true
    add_foreign_key :uploads, :users

This will add a new foreign key to the user_id column of the uploads table. The key references the id column in users table.

NOTE: This is in addition to adding a reference so you still need to create a reference first then foreign key (you can choose to create a foreign key in the same migration or a separate migration file). Active Record only supports single column foreign keys and currently only mysql, mysql2 and PostgreSQL adapters are supported. Don't try this with other adapters like sqlite3, etc. Refer to Rails Guides: Foreign Keys for your reference.

IFRAMEs and the Safari on the iPad, how can the user scroll the content?

-webkit-overflow-scrolling:touch as mentioned in the answer is infact the possible solution.

<div style="overflow:scroll !important; -webkit-overflow-scrolling:touch !important;">
     <iframe src="YOUR_PAGE_URL" width="600" height="400"></iframe>

But if you are unable to scroll up and down inside the iframe as shown in image below, enter image description here

you could try scrolling with 2 fingers diagonally like this,

enter image description here

This actually worked in my case, so just sharing it if you haven't still found a solution for this.

Saving any file to in the database, just convert it to a byte array?

While you can store files in this fashion, it has significant tradeoffs:

  • Most DBs are not optimized for giant quantities of binary data, and query performance often degrades dramatically as the table bloats, even with indexes. (SQL Server 2008, with the FILESTREAM column type, is the exception to the rule.)
  • DB backup/replication becomes extremely slow.
  • It's a lot easier to handle a corrupted drive with 2 million images -- just replace the disk on the RAID -- than a DB table that becomes corrupted.
  • If you accidentally delete a dozen images on a filesystem, your operations guys can replace them pretty easily from a backup, and since the table index is tiny by comparison, it can be restored quickly. If you accidentally delete a dozen images in a giant database table, you have a long and painful wait to restore the DB from backup, paralyzing your entire system in the meantime.

These are just some of the drawbacks I can come up with off the top of my head. For tiny projects it may be worth storing files in this fashion, but if you're designing enterprise-grade software I would strongly recommend against it.

jQuery: Get selected element tag name

You should NOT use jQuery('selector').attr("tagName").toLowerCase(), because it only works in older versions of Jquery.

You could use $('selector').prop("tagName").toLowerCase() if you're certain that you're using a version of jQuery thats >= version 1.6.

Note :

You may think that EVERYONE is using jQuery 1.10+ or something by now (January 2016), but unfortunately that isn't really the case. For example, many people today are still using Drupal 7, and every official release of Drupal 7 to this day includes jQuery 1.4.4 by default.

So if do not know for certain if your project will be using jQuery 1.6+, consider using one of the options that work for ALL versions of jQuery :

Option 1 :


Option 2


Getting list of Facebook friends with latest API

I think this is what you want:

$friends = $facebook->api('/me/friends');

Adding a Button to a WPF DataGrid

First create a DataGridTemplateColumn to contain the button:

      <Button Click="ShowHideDetails">Details</Button> 

When the button is clicked, update the containing DataGridRow's DetailsVisibility:

void ShowHideDetails(object sender, RoutedEventArgs e)
    for (var vis = sender as Visual; vis != null; vis = VisualTreeHelper.GetParent(vis) as Visual)
    if (vis is DataGridRow)
        var row = (DataGridRow)vis;
        row.DetailsVisibility = 
        row.DetailsVisibility == Visibility.Visible ? Visibility.Collapsed : Visibility.Visible;

Subclipse svn:ignore

This is quite frustrating, but it's a containment issue (the .svn folders keep track also of ignored files). Any item that needs to be ignored is to be added to the ignore list of the immediate parent folder.

So, I had a new sub-folder with a new file in it and wanted to ignore that file but I couldn't do it because the option was grayed out. I solved it by committing the new folder first, which I wanted to (it was a cache folder), and then adding that file to the ignore list (of the newly added folder ;-), having the chance to add a pattern instead of a single file.

CSS @font-face not working with Firefox, but working with Chrome and IE

If you are trying to import external fonts you face one of the most common problem with your Firefox and other browser. Some time your font working well in google Chrome or one of the other browser but not in every browser.

There have lots of reason for this type of error one of the biggest reason behind this problem is previous per-defined font. You need to add !important keyword after end of your each line of CSS code as below:


    font-family:"Hacen Saudi Arabia" !important;
    src:url("../font/Hacen_Saudi_Arabia.eot?") format("eot") !important;
    src:url("../font/Hacen_Saudi_Arabia.woff") format("woff") !important;
    src: url("../font/Hacen_Saudi_Arabia.ttf") format("truetype") !important;
    src:url("../font/Hacen_Saudi_Arabia.svg#HacenSaudiArabia") format("svg") !important;
    font-family:"Hacen Saudi Arabia" !important;

Description: Enter above code in your CSS file or code here. In above example replace "Hacen Saudi Arabia" with your font-family and replace url as per your font directory.

If you enter !important in your css code browser automatically focus on this section and override previously used property. For More details visit:

Recreate the default website in IIS

You can try to restore your previous state by doing the following:

  1. Go to IIS Manager
  2. Right-click on your Local Computer.
  3. Point to All Tasks
  4. Point to Backup/Restore Configuration
  5. Select the configuration you want to restore
  6. Wait untill configuration applies

Change content of div - jQuery

 $('#content-container').html('My content here :-)');

Using @property versus getters and setters

In complex projects I prefer using read-only properties (or getters) with explicit setter function:

class MyClass(object):
def my_attr(self):

def set_my_attr(self, value):

In long living projects debugging and refactoring takes more time than writing the code itself. There are several downsides for using @property.setter that makes debugging even harder:

1) python allows creating new attributes for an existing object. This makes a following misprint very hard to track:

my_object.my_atttr = 4.

If your object is a complicated algorithm then you will spend quite some time trying to find out why it doesn't converge (notice an extra 't' in the line above)

2) setter sometimes might evolve to a complicated and slow method (e.g. hitting a database). It would be quite hard for another developer to figure out why the following function is very slow. He might spend a lot of time on profiling do_something() method, while my_object.my_attr = 4. is actually the cause of slowdown:

def slow_function(my_object):
    my_object.my_attr = 4.

How to install all required PHP extensions for Laravel?

Laravel Server Requirements mention that BCMath, Ctype, JSON, Mbstring, OpenSSL, PDO, Tokenizer, and XML extensions are required. Most of the extensions are installed and enabled by default.

You can run the following command in Ubuntu to make sure the extensions are installed.

sudo apt install openssl php-common php-curl php-json php-mbstring php-mysql php-xml php-zip

PHP version specific installation (if PHP 7.4 installed)

sudo apt install php7.4-common php7.4-bcmath openssl php7.4-json php7.4-mbstring

You may need other PHP extensions for your composer packages. Find from links below.

PHP extensions for Ubuntu 20.04 LTS (Focal Fossa)

PHP extensions for Ubuntu 18.04 LTS (Bionic)

PHP extensions for Ubuntu 16.04 LTS (Xenial)

SQL Query to search schema of all tables

I would query the information_schema - this has views that are much more readable than the underlying tables.


C# - Simplest way to remove first occurrence of a substring from another string

int index = sourceString.IndexOf(removeString);
string cleanPath = (index < 0)
    ? sourceString
    : sourceString.Remove(index, removeString.Length);

Gmail: 530 5.5.1 Authentication Required. Learn more at

Derp! I signed into the account and there was a "Suspicious login attempt" warning message at the top of the page. After clicking the warning and authorizing the access, everything works.

Nested ifelse statement

Using the SQL CASE statement with the dplyr and sqldf packages:


df <-structure(list(idnat = structure(c(2L, 2L, 2L, 1L), .Label = c("foreign", 
"french"), class = "factor"), idbp = structure(c(3L, 1L, 4L, 
2L), .Label = c("colony", "foreign", "mainland", "overseas"), class = "factor")), .Names = c("idnat", 
"idbp"), class = "data.frame", row.names = c(NA, -4L))


sqldf("SELECT idnat, idbp,
          WHEN idbp IN ('colony', 'overseas') THEN 'overseas' 
          ELSE idbp 
        END AS idnat2
       FROM df")


df %>% 
mutate(idnat2 = case_when(.$idbp == 'mainland' ~ "mainland", 
                          .$idbp %in% c("colony", "overseas") ~ "overseas", 
                         TRUE ~ "foreign"))


    idnat     idbp   idnat2
1  french mainland mainland
2  french   colony overseas
3  french overseas overseas
4 foreign  foreign  foreign

Jquery open popup on button click for bootstrap

The answer is on the example link you provided:


Call a modal with id myModal with a single line of JavaScript:


jQuery: How can I show an image popup onclick of the thumbnail?

I was in the same situation and found this one,


How to pass arguments within docker-compose?

Now docker-compose supports variable substitution.

Compose uses the variable values from the shell environment in which docker-compose is run. For example, suppose the shell contains POSTGRES_VERSION=9.3 and you supply this configuration in your docker-compose.yml file:

  image: "postgres:${POSTGRES_VERSION}"

When you run docker-compose up with this configuration, Compose looks for the POSTGRES_VERSION environment variable in the shell and substitutes its value in. For this example, Compose resolves the image to postgres:9.3 before running the configuration.

How to create an 2D ArrayList in java?

ArrayList<String>[][] list = new ArrayList[10][10];
list[0][0] = new ArrayList<>();

Understanding CUDA grid dimensions, block dimensions and threads organization (simple explanation)

Suppose a 9800GT GPU:

  • it has 14 multiprocessors (SM)
  • each SM has 8 thread-processors (AKA stream-processors, SP or cores)
  • allows up to 512 threads per block
  • warpsize is 32 (which means each of the 14x8=112 thread-processors can schedule up to 32 threads)

A block cannot have more active threads than 512 therefore __syncthreads can only synchronize limited number of threads. i.e. If you execute the following with 600 threads:


then the kernel must run twice and the order of execution will be:

  1. func1 is executed for the first 512 threads
  2. func2 is executed for the first 512 threads
  3. func1 is executed for the remaining threads
  4. func2 is executed for the remaining threads


The main point is __syncthreads is a block-wide operation and it does not synchronize all threads.

I'm not sure about the exact number of threads that __syncthreads can synchronize, since you can create a block with more than 512 threads and let the warp handle the scheduling. To my understanding it's more accurate to say: func1 is executed at least for the first 512 threads.

Before I edited this answer (back in 2010) I measured 14x8x32 threads were synchronized using __syncthreads.

I would greatly appreciate if someone test this again for a more accurate piece of information.

Difference between uint32 and uint32_t

uint32_t is defined in the standard, in

18.4.1 Header <cstdint> synopsis [cstdint.syn]

namespace std {
typedef unsigned integer type uint32_t; // optional

uint32 is not, it's a shortcut provided by some compilers (probably as typedef uint32_t uint32) for ease of use.

Creating and writing lines to a file

' Create The Object
Set FSO = CreateObject("Scripting.FileSystemObject")

' How To Write To A File
Set File = FSO.CreateTextFile("C:\foo\bar.txt",True)
File.Write "Example String"

' How To Read From A File
Set File = FSO.OpenTextFile("C:\foo\bar.txt")
Do Until File.AtEndOfStream
    Line = File.ReadLine

' Another Method For Reading From A File
Set File = FSO.OpenTextFile("C:\foo\bar.txt")
Set Text = File.ReadAll

How to install Visual C++ Build tools?

You can check Announcing the official release of the Visual C++ Build Tools 2015 and from this blog, we can know that the Build Tools are the same C++ tools that you get with Visual Studio 2015 but they come in a scriptable standalone installer that only lays down the tools you need to build C++ projects. The Build Tools give you a way to install the tools you need on your build machines without the IDE you don’t need.

Because these components are the same as the ones installed by the Visual Studio 2015 Update 2 setup, you cannot install the Visual C++ Build Tools on a machine that already has Visual Studio 2015 installed. Therefore, it asks you to uninstall your existing VS 2015 when you tried to install the Visual C++ build tools using the standalone installer. Since you already have the VS 2015, you can go to Control Panel—Programs and Features and right click the VS 2015 item and Change-Modify, then check the option of those components that relates to the Visual C++ Build Tools, like Visual C++, Windows SDK… then install them. After the installation is successful, you can build the C++ projects.

Can I create links with 'target="_blank"' in Markdown?

For completed alex answered (Dec 13 '10)

A more smart injection target could be done with this code :

 * For all links in the current page...
$(document.links).filter(function() {
     * ...keep them without `target` already setted...
    return !;
}).filter(function() {
     * ...and keep them are not on current domain...
    return this.hostname !== window.location.hostname ||
         * ...or are not a web file (.pdf, .jpg, .png, .js, .mp4, etc.).
 * For all link kept, add the `target="_blank"` attribute. 
}).attr('target', '_blank');

You could change the regexp exceptions with adding more extension in (?!html?|php3?|aspx?) group construct (understand this regexp here:

and for a without jQuery version, check code below:

var links = document.links;
for (var i = 0; i < links.length; i++) {
    if (!links[i].target) {
        if (
            links[i].hostname !== window.location.hostname || 
        ) {
            links[i].target = '_blank';

Start HTML5 video at a particular position when loading?


Just add #t=[(start_time), (end_time)] to the end of your media URL. The only setback (if you want to see it that way) is you'll need to know how long your video is to indicate the end time. Example:

    <source src="splash.mp4#t=10,20" type="video/mp4">

Notes: Not supported in IE

LaTeX source code listing like in professional books

And please, whatever you do, configure the listings package to use fixed-width font (as in your example; you'll find the option in the documentation). Default setting uses proportional font typeset on a grid, which is, IMHO, incredibly ugly and unreadable, as can be seen from the other answers with pictures. I am personally very irritated when I must read some code typeset in a proportional font.

Try setting fixed-width font with this:


Add newline to VBA or Visual Basic 6

Use this code between two words:

& vbCrLf &

Using this, the next word displays on the next line.

How to find length of a string array?

As all the above answers have suggested it will throw a NullPointerException.

Please initialise it with some value(s) and then you can use the length property correctly. For example:

String[] str = { "plastic", "paper", "use", "throw" };
System.out.println("Length is:::" + str.length);

The array 'str' is now defined, and so it's length also has a defined value.

Changing CSS for last <li>

:last-child is really the only way to do it without modifying the HTML - but assuming you can do that, the main option is just to give it a class="last-item", then do:

li.last-item { /* ... */ }

Obviously, you can automate this in the dynamic page generation language of your choice. Also, there is a lastChild JavaScript property in the W3C DOM.

Here's an example of doing what you want in Prototype:

$$("ul").each(function(x) { $(x.lastChild).addClassName("last-item"); });

Or even more simply:

$$("ul li:last-child").each(function(x) { x.addClassName("last-item"); });

In jQuery, you can write it even more compactly:

$("ul li:last-child").addClass("last-item");

Also note that this should work without using the actual last-child CSS selector - rather, a JavaScript implementation of it is used - so it should be less buggy and more reliable across browsers.

How to Convert Excel Numeric Cell Value into Words

There is no built-in formula in excel, you have to add a vb script and permanently save it with your MS. Excel's installation as Add-In.

  1. press Alt+F11
  2. MENU: (Tool Strip) Insert Module
  3. copy and paste the below code

Option Explicit

Public Numbers As Variant, Tens As Variant

Sub SetNums()
    Numbers = Array("", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen")
    Tens = Array("", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety")
End Sub

Function WordNum(MyNumber As Double) As String
    Dim DecimalPosition As Integer, ValNo As Variant, StrNo As String
    Dim NumStr As String, n As Integer, Temp1 As String, Temp2 As String
    ' This macro was written by Chris Mead -
    If Abs(MyNumber) > 999999999 Then
        WordNum = "Value too large"
        Exit Function
    End If
    ' String representation of amount (excl decimals)
    NumStr = Right("000000000" & Trim(Str(Int(Abs(MyNumber)))), 9)
    ValNo = Array(0, Val(Mid(NumStr, 1, 3)), Val(Mid(NumStr, 4, 3)), Val(Mid(NumStr, 7, 3)))
    For n = 3 To 1 Step -1    'analyse the absolute number as 3 sets of 3 digits
        StrNo = Format(ValNo(n), "000")
        If ValNo(n) > 0 Then
            Temp1 = GetTens(Val(Right(StrNo, 2)))
            If Left(StrNo, 1) <> "0" Then
                Temp2 = Numbers(Val(Left(StrNo, 1))) & " hundred"
                If Temp1 <> "" Then Temp2 = Temp2 & " and "
                Temp2 = ""
            End If
            If n = 3 Then
                If Temp2 = "" And ValNo(1) + ValNo(2) > 0 Then Temp2 = "and "
                WordNum = Trim(Temp2 & Temp1)
            End If
            If n = 2 Then WordNum = Trim(Temp2 & Temp1 & " thousand " & WordNum)
            If n = 1 Then WordNum = Trim(Temp2 & Temp1 & " million " & WordNum)
        End If
    Next n
    NumStr = Trim(Str(Abs(MyNumber)))
    ' Values after the decimal place
    DecimalPosition = InStr(NumStr, ".")
    Numbers(0) = "Zero"
    If DecimalPosition > 0 And DecimalPosition < Len(NumStr) Then
        Temp1 = " point"
        For n = DecimalPosition + 1 To Len(NumStr)
            Temp1 = Temp1 & " " & Numbers(Val(Mid(NumStr, n, 1)))
        Next n
        WordNum = WordNum & Temp1
    End If
    If Len(WordNum) = 0 Or Left(WordNum, 2) = " p" Then
        WordNum = "Zero" & WordNum
    End If
End Function

Function GetTens(TensNum As Integer) As String
' Converts a number from 0 to 99 into text.
    If TensNum <= 19 Then
        GetTens = Numbers(TensNum)
        Dim MyNo As String
        MyNo = Format(TensNum, "00")
        GetTens = Tens(Val(Left(MyNo, 1))) & " " & Numbers(Val(Right(MyNo, 1)))
    End If
End Function

After this, From File Menu select Save Book ,from next menu select "Excel 97-2003 Add-In (*.xla)

It will save as Excel Add-In. that will be available till the Ms.Office Installation to that machine.

Now Open any Excel File in any Cell type =WordNum(<your numeric value or cell reference>)

you will see a Words equivalent of the numeric value.

This Snippet of code is taken from:

How to compress image size?

use this class to compress image

import android.content.Context
import android.os.Environment

class ImageFile(val uri: Uri, name: String) {

    val filename: String

    init {
        val file = File(Environment.getExternalStorageDirectory().toString() + "/Documents")
        if (!file.exists()) {
        val fileNoMedia = File(file.absolutePath + "/.nomedia")
        if (!fileNoMedia.exists())
        if (name.toLowerCase().endsWith(".pdf")) {
            filename = file.absolutePath + "/" + System.currentTimeMillis() + ".pdf"
        } else {
            filename = file.absolutePath + "/" + System.currentTimeMillis() + ".jpg"

    fun copyFileStream(context: Context, uri: Uri): String {
        if (filename.endsWith(".pdf") || filename.endsWith(".PDF")) {
            var ins: InputStream? = null
            var os: OutputStream? = null
            try {
                ins = context.getContentResolver().openInputStream(uri)
                os = FileOutputStream(filename)
                val buffer = ByteArray(1024)
                var length: Int =
                while (length > 0) {
                    os.write(buffer, 0, length);
                    length =
            } catch (e: Exception) {
            } finally {
        } else {
            var ins: InputStream? = null
            var os: OutputStream? = null
            try {
                ins = context.getContentResolver().openInputStream(uri)
                var scaledBitmap: Bitmap? = null
                val options = BitmapFactory.Options()
                options.inJustDecodeBounds = true
                var bmp = BitmapFactory.decodeStream(ins, null, options)
                var actualHeight = options.outHeight
                var actualWidth = options.outWidth

                //      max Height and width values of the compressed image is taken as 816x612
                val maxHeight = 816.0f
                val maxWidth = 612.0f
                var imgRatio = (actualWidth / actualHeight).toFloat()
                val maxRatio = maxWidth / maxHeight

                //      width and height values are set maintaining the aspect ratio of the image
                if (actualHeight > maxHeight || actualWidth > maxWidth) {
                    if (imgRatio < maxRatio) {
                        imgRatio = maxHeight / actualHeight
                        actualWidth = (imgRatio * actualWidth).toInt()
                        actualHeight = maxHeight.toInt()
                    } else if (imgRatio > maxRatio) {
                        imgRatio = maxWidth / actualWidth
                        actualHeight = (imgRatio * actualHeight).toInt()
                        actualWidth = maxWidth.toInt()
                    } else {
                        actualHeight = maxHeight.toInt()
                        actualWidth = maxWidth.toInt()


                //      setting inSampleSize value allows to load a scaled down version of the original image
                options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight)

                //      inJustDecodeBounds set to false to load the actual bitmap
                options.inJustDecodeBounds = false

                //      this options allow android to claim the bitmap memory if it runs low on memory
                options.inPurgeable = true
                options.inInputShareable = true
                options.inTempStorage = ByteArray(16 * 1024)

                try {
                    //          load the bitmap from its path
                    ins = context.getContentResolver().openInputStream(uri)
                    bmp = BitmapFactory.decodeStream(ins, null, options)
                } catch (exception: OutOfMemoryError) {


                try {
                    scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888)
                } catch (exception: OutOfMemoryError) {

                val ratioX = actualWidth / options.outWidth.toFloat()
                val ratioY = actualHeight / options.outHeight.toFloat()
                val middleX = actualWidth / 2.0f
                val middleY = actualHeight / 2.0f

                val scaleMatrix = Matrix()
                scaleMatrix.setScale(ratioX, ratioY, middleX, middleY)

                val canvas = Canvas(scaledBitmap!!)
                canvas.matrix = scaleMatrix
                canvas.drawBitmap(bmp, middleX - bmp.width / 2, middleY - bmp.height / 2, Paint(Paint.FILTER_BITMAP_FLAG))

                os = FileOutputStream(filename)
                scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, os)
                val buffer = ByteArray(1024)
                var length: Int =
                while (length > 0) {
                    os.write(buffer, 0, length);
                    length =
            } catch (e: Exception) {
            } finally {
        return filename

    fun calculateInSampleSize(options: BitmapFactory.Options, reqWidth: Int, reqHeight: Int): Int {
        val height = options.outHeight
        val width = options.outWidth
        var inSampleSize = 1
        if (height > reqHeight || width > reqWidth) {
            val heightRatio = Math.round(height.toFloat() / reqHeight.toFloat())
            val widthRatio = Math.round(width.toFloat() / reqWidth.toFloat())
            inSampleSize = if (heightRatio < widthRatio) heightRatio else widthRatio
        val totalPixels = (width * height).toFloat()
        val totalReqPixelsCap = (reqWidth * reqHeight * 2).toFloat()
        while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {

        return inSampleSize

JavaScript getElementByID() not working

Because when the script executes the browser has not yet parsed the <body>, so it does not know that there is an element with the specified id.

Try this instead:

    <script type="text/javascript">
        window.onload = (function () {
            var refButton = document.getElementById("btnButton");

            refButton.onclick = function() {
                alert('Dhoor shala!');
    <form id="form1">
        <input id="btnButton" type="button" value="Click me"/>

Note that you may as well use addEventListener instead of window.onload = ... to make that function only execute after the whole document has been parsed.

Which is better, return value or out parameter?

There's one reason to use an out param which has not already been mentioned: the calling method is obliged to receive it. If your method produces a value which the caller should not discard, making it an out forces the caller to specifically accept it:

 Method1();  // Return values can be discard quite easily, even accidentally

 int  resultCode;
 Method2(out resultCode);  // Out params are a little harder to ignore

Of course the caller can still ignore the value in an out param, but you've called their attention to it.

This is a rare need; more often, you should use an exception for a genuine problem or return an object with state information for an "FYI", but there could be circumstances where this is important.

How to get relative path from absolute path

I have used this in the past.

/// <summary>
/// Creates a relative path from one file
/// or folder to another.
/// </summary>
/// <param name="fromDirectory">
/// Contains the directory that defines the
/// start of the relative path.
/// </param>
/// <param name="toPath">
/// Contains the path that defines the
/// endpoint of the relative path.
/// </param>
/// <returns>
/// The relative path from the start
/// directory to the end path.
/// </returns>
/// <exception cref="ArgumentNullException"></exception>
public static string MakeRelative(string fromDirectory, string toPath)
  if (fromDirectory == null)
    throw new ArgumentNullException("fromDirectory");

  if (toPath == null)
    throw new ArgumentNullException("toPath");

  bool isRooted = (Path.IsPathRooted(fromDirectory) && Path.IsPathRooted(toPath));

  if (isRooted)
    bool isDifferentRoot = (string.Compare(Path.GetPathRoot(fromDirectory), Path.GetPathRoot(toPath), true) != 0);

    if (isDifferentRoot)
      return toPath;

  List<string> relativePath = new List<string>();
  string[] fromDirectories = fromDirectory.Split(Path.DirectorySeparatorChar);

  string[] toDirectories = toPath.Split(Path.DirectorySeparatorChar);

  int length = Math.Min(fromDirectories.Length, toDirectories.Length);

  int lastCommonRoot = -1;

  // find common root
  for (int x = 0; x < length; x++)
    if (string.Compare(fromDirectories[x], toDirectories[x], true) != 0)

    lastCommonRoot = x;

  if (lastCommonRoot == -1)
    return toPath;

  // add relative folders in from path
  for (int x = lastCommonRoot + 1; x < fromDirectories.Length; x++)
    if (fromDirectories[x].Length > 0)

  // add to folders to path
  for (int x = lastCommonRoot + 1; x < toDirectories.Length; x++)

  // create relative path
  string[] relativeParts = new string[relativePath.Count];
  relativePath.CopyTo(relativeParts, 0);

  string newPath = string.Join(Path.DirectorySeparatorChar.ToString(), relativeParts);

  return newPath;

Reading a text file with SQL Server

What does your text file look like?? Each line a record?

You'll have to check out the BULK INSERT statement - that should look something like:

BULK INSERT dbo.YourTableName
FROM 'D:\directory\YourFileName.csv'
  CODEPAGE = '1252',

Here, in my case, I'm importing a CSV file - but you should be able to import a text file just as well.

From the MSDN docs - here's a sample that hopefully works for a text file with one field per row:

BULK INSERT dbo.temp 
   FROM 'c:\temp\file.txt'
         ROWTERMINATOR ='\n'

Seems to work just fine in my test environment :-)

Share cookie between subdomain and domain

I'm not sure @cmbuckley answer is showing the full picture. What I read is:

Unless the cookie's attributes indicate otherwise, the cookie is returned only to the origin server (and not, for example, to any subdomains), and it expires at the end of the current session (as defined by the user agent). User agents ignore unrecognized cookie.

RFC 6265


8.6.  Weak Integrity

   Cookies do not provide integrity guarantees for sibling domains (and
   their subdomains).  For example, consider and  The server can set a cookie with a
   Domain attribute of "" (possibly overwriting an existing
   "" cookie set by, and the user agent will
   include that cookie in HTTP requests to  In the
   worst case, will be unable to distinguish this cookie
   from a cookie it set itself.  The server might be
   able to leverage this ability to mount an attack against

To me that means you can protect cookies from being read by subdomain/domain but cannot prevent writing cookies to the other domains. So somebody may rewrite your site cookies by controlling another subdomain visited by the same browser. Which might not be a big concern.

Awesome cookies test site provided by @cmbuckley /for those that missed it in his answer like me; worth scrolling up and upvoting/:

Python str vs unicode types

unicode is meant to handle text. Text is a sequence of code points which may be bigger than a single byte. Text can be encoded in a specific encoding to represent the text as raw bytes(e.g. utf-8, latin-1...).

Note that unicode is not encoded! The internal representation used by python is an implementation detail, and you shouldn't care about it as long as it is able to represent the code points you want.

On the contrary str in Python 2 is a plain sequence of bytes. It does not represent text!

You can think of unicode as a general representation of some text, which can be encoded in many different ways into a sequence of binary data represented via str.

Note: In Python 3, unicode was renamed to str and there is a new bytes type for a plain sequence of bytes.

Some differences that you can see:

>>> len(u'à')  # a single code point
>>> len('à')   # by default utf-8 -> takes two bytes
>>> len(u'à'.encode('utf-8'))
>>> len(u'à'.encode('latin1'))  # in latin1 it takes one byte
>>> print u'à'.encode('utf-8')  # terminal encoding is utf-8
>>> print u'à'.encode('latin1') # it cannot understand the latin1 byte

Note that using str you have a lower-level control on the single bytes of a specific encoding representation, while using unicode you can only control at the code-point level. For example you can do:

>>> 'àèìòù'
>>> print 'àèìòù'.replace('\xa8', '')

What before was valid UTF-8, isn't anymore. Using a unicode string you cannot operate in such a way that the resulting string isn't valid unicode text. You can remove a code point, replace a code point with a different code point etc. but you cannot mess with the internal representation.

How do I write a "tab" in Python?

As it wasn't mentioned in any answers, just in case you want to align and space your text, you can use the string format features. (above python 2.5) Of course \t is actually a TAB token whereas the described method generates spaces.


print "{0:30} {1}".format("hi", "yes")
> hi                             yes

Another Example, left aligned:

print("{0:<10} {1:<10} {2:<10}".format(1.0, 2.2, 4.4))
>1.0        2.2        4.4 

Python - Extracting and Saving Video Frames

To extend on this question (& answer by @user2700065) for a slightly different cases, if anyone does not want to extract every frame but wants to extract frame every one second. So a 1-minute video will give 60 frames(images).

import sys
import argparse

import cv2

def extractImages(pathIn, pathOut):
    count = 0
    vidcap = cv2.VideoCapture(pathIn)
    success,image =
    success = True
    while success:
        vidcap.set(cv2.CAP_PROP_POS_MSEC,(count*1000))    # added this line 
        success,image =
        print ('Read a new frame: ', success)
        cv2.imwrite( pathOut + "\\frame%d.jpg" % count, image)     # save frame as JPEG file
        count = count + 1

if __name__=="__main__":
    a = argparse.ArgumentParser()
    a.add_argument("--pathIn", help="path to video")
    a.add_argument("--pathOut", help="path to images")
    args = a.parse_args()
    extractImages(args.pathIn, args.pathOut)

What are Java command line options to set to allow JVM to be remotely debugged?

Command Line

-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=PORT_NUMBER


gradle bootrun --debug-jvm


mvn spring-boot:run -Drun.jvmArguments="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=PORT_NUMBER

How can I draw circle through XML Drawable - Android?

no need for the padding or the corners.

here's a sample:

<shape xmlns:android="" android:shape="oval" >
    <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF"

based on :

Unable to connect to mongodb Error: couldn't connect to server at src/mongo/shell/mongo.js:L112

Faced same issue, my understanding is(it could be wrong)
1. Make sure mongodb is up and running
2. For linux access as sudo and for windows if connecting localhost turning off firewall may help but its not necessary
3. Just type mongo, it will try to connect to localhost by default. You need to specify IP if you are connecting to a remote server. By default test db will be used.

How to monitor SQL Server table changes by using c#?

Another, very simple way of monitoring tables is table versioning. The system is proven working in constructions such as DNS synchronization. To make it work you create a table containing table names and table versions as decimal or bigint.In each table that you need monitored, create trigger on insert, update and delete that will increment appropriate table version in versioning table when executed. If you expect any of the monitored tables to be altered often, you need to provision for version reusing. Finally, in your application, every time you query monitored table, you also query its version and store it. When you go to alter the monitored table from your app, you first query its current version and process the change only if the version is unchanged. You can have stored proc on sql server do that work for you. This is extremely simple but proven solid solution. It has specific functional use (to ensure data consistency) and is light on resources (you do not raise brokered events that you would not watch for) but needs application to actively check for changes rather than passively wait for event to happen.

HTML SELECT - Change selected option by VALUE using JavaScript

try out this....


using javascript

?document.getElementById('sel').value = 'car';??????????

using jQuery


PDF to byte array and vice versa

You basically need a helper method to read a stream into memory. This works pretty well:

public static byte[] readFully(InputStream stream) throws IOException
    byte[] buffer = new byte[8192];
    ByteArrayOutputStream baos = new ByteArrayOutputStream();

    int bytesRead;
    while ((bytesRead = != -1)
        baos.write(buffer, 0, bytesRead);
    return baos.toByteArray();

Then you'd call it with:

public static byte[] loadFile(String sourcePath) throws IOException
    InputStream inputStream = null;
        inputStream = new FileInputStream(sourcePath);
        return readFully(inputStream);
        if (inputStream != null)

Don't mix up text and binary data - it only leads to tears.

Can I mask an input text in a bat file?

Another option, along the same lines as Blorgbeard is out's, is to use something like:

SET /P pw=C:\^>

The ^ escapes the > so that the password prompt will look like a standard cmd console prompt.

Why is vertical-align: middle not working on my span or div?

Here you have an example of two ways of doing a vertical alignment. I use them and they work pretty well. One is using absolute positioning and the other using flexbox.

Vertical Align Example

Using flexbox, you can align an element by itself inside another element with display: flex; using align-self. If you need to align it also horizontally, you can use align-items and justify-content in the container.

If you don't want to use flexbox, you can use the position property. If you make the container relative and the content absolute, the content will be able to move freely inside the container. So if you use top: 0; and left: 0; in the content, it will be positioned at the top left corner of the container.

Absolute positioning

Then, to align it, you just need to change the top and left references to 50%. This will position the content at the container center from the top left corner of the content.

Align in the middle of the container

So you need to correct this translating the content half its size to the left and top.

Absolute centered

Keep only date part when using pandas.to_datetime

Pandas v0.13+: Use to_csv with date_format parameter

Avoid, where possible, converting your datetime64[ns] series to an object dtype series of objects. The latter, often constructed using, is stored as an array of pointers and is inefficient relative to a pure NumPy-based series.

Since your concern is format when writing to CSV, just use the date_format parameter of to_csv. For example:

df.to_csv(filename, date_format='%Y-%m-%d')

See Python's strftime directives for formatting conventions.

How to launch an EXE from Web page (

Are you saying that you are having trouble inserting into a web page a link to a file that happens to have a .exe extension?

If that is the case, then take one step back. Imagine the file has a .htm extension, or a .css extension. How can you make that downloadable? If it is a static link, then the answer is clear: the file needs to be in the docroot for the ASP.NET app. IIS + ASP.NET serves up many kinds of content: .htm files, .css files, .js files, image files, implicitly. All these files are somewhere under the docroot, which by default is c:\inetpub\wwwroot, but for your webapp is surely something different. The fact that the file you want to expose has an .exe extension does not change the basic laws of IIS physics. The exe has to live under the docroot. The network share thing might work for some browsers.

The alternative of course is to dynamically write the content of the file directly to the Response.OutputStream. This way you don't need the .exe to be in your docroot, but it is not a direct download link. In this scenario, the file might be downloaded by a button click.

Something like this:

    string FullPathFilename = "\\\\server\\share\\CorpApp1.exe";
    string archiveName= System.IO.Path.GetFileName(FullPathFilename);
    Response.ContentType = "application/octet-stream";
    Response.AddHeader("content-disposition", "filename=" + archiveName);

Get current URL path in PHP

function current_url()
    $url      = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    $validURL = str_replace("&", "&amp", $url);
    return $validURL;
//echo "page URL is : ".current_url();

$offer_url = current_url();



if ($offer_url == "checking url name") {
?> <p> hi this is manip5595 </p>


Is there a way to use max-width and height for a background image?

As thirtydot said, you can use the CSS3 background-size syntax:

For example:

-o-background-size:35% auto;
-webkit-background-size:35% auto;
-moz-background-size:35% auto;
background-size:35% auto;

However, as also stated by thirtydot, this does not work in IE6, 7 and 8.

See the following links for more information about background-size:

how to write value into cell with vba code without auto type conversion?

This is probably too late, but I had a similar problem with dates that I wanted entered into cells from a text variable. Inevitably, it converted my variable text value to a date. What I finally had to do was concatentate a ' to the string variable and then put it in the cell like this:

prvt_rng_WrkSht.Cells(prvt_rng_WrkSht.Rows.Count, cnst_int_Col_Start_Date).Formula = "'" & _ 
    param_cls_shift.Start_Date (string property of my class) 

How do I call one constructor from another in Java?

There are design patterns that cover the need for complex construction - if it can't be done succinctly, create a factory method or a factory class.

With the latest java and the addition of lambdas, it is easy to create a constructor which can accept any initialization code you desire.

class LambdaInitedClass {

   public LamdaInitedClass(Consumer<LambdaInitedClass> init) {

Call it with...

 new LambdaInitedClass(l -> { // init l any way you want });

How to validate an email address in PHP

If you're just looking for an actual regex that allows for various dots, underscores and dashes, it as follows: [a-zA-z0-9.-]+\@[a-zA-z0-9.-]+.[a-zA-Z]+. That will allow a fairly stupid looking email like to be validated.

How do I set default value of select box in angularjs

if you don't even want to initialize ng-model to a static value and each value is DB driven, it can be done in the following way. Angular compares the evaluated value and populates the drop down.

Here below modelData.unitId is retrieved from DB and is compared to the list of unit id which is a separate list from db-

 <select id="uomList" ng-init="modelData.unitId"_x000D_
                         ng-model="modelData.unitId" ng-options=" as unitOfMeasurement.unitName for unitOfMeasurement in unitOfMeasurements">

Update multiple tables in SQL Server using INNER JOIN

You can't update more that one table in a single statement, however the error message you get is because of the aliases, you could try this :


update A
from table1 A inner join table2 B
and A.ORG_ID = @ORG_ID

update B
from table2 B inner join table1 A
    on B.ORG_ID = A.ORG_ID
    and A.ORG_ID = @ORG_ID


java, get set methods

your panel class don't have a constructor that accepts a string

try change

RLS_strid_panel p = new RLS_strid_panel(namn1);


RLS_strid_panel p = new RLS_strid_panel();

How to enable scrolling of content inside a modal?

Bootstrap will add or remove a css "modal-open" to the <body> tag when we open or close a modal. So if you open multiple modal and then close arbitrary one, the modal-open css will be removed from the body tag.

But the scroll effect depend on the attribute "overflow-y: auto;" defined in modal-open

spark submit add multiple jars in classpath

Pass --jars with the path of jar files separated by , to spark-submit.

For reference:

--driver-class-path is used to mention "extra" jars to add to the "driver" of the spark job

--driver-library-path is used to "change" the default library path for the jars needed for the spark driver

--driver-class-path will only push the jars to the driver machine. If you want to send the jars to "executors", you need to use --jars

And to set the jars programatically set the following config: spark.yarn.dist.jars with comma-separated list of jars.


from pyspark.sql import SparkSession

spark = SparkSession \
        .builder \
        .appName("Spark config example") \
        .config("spark.yarn.dist.jars", "<path-to-jar/test1.jar>,<path-to-jar/test2.jar>") \

How do I add a custom script to my package.json file that runs a javascript file?

Suppose I have this line of scripts in my "package.json"

"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "export_advertisements": "node export.js advertisements",
    "export_homedata": "node export.js homedata",
    "export_customdata": "node export.js customdata",
    "export_rooms": "node export.js rooms"

Now to run the script "export_advertisements", I will simply go to the terminal and type

npm run export_advertisements

You are most welcome

How do I find the number of arguments passed to a Bash script?

that value is contained in the variable $#

Firebase (FCM) how to get token

At the same time don not forget to include this in your manifest file to receive token id

        <action android:name=""/>

Laravel use same form for create and edit

I like to use form model binding so I can easily populate a form's fields with corresponding value, so I follow this approach (using a user model for example):

    {{ Form::model($user, ['route' => ['updateroute', $user->id], 'method' => 'patch']) }}
    {{ Form::open(['route' => 'createroute']) }}

    {{ Form::text('fieldname1', Input::old('fieldname1')) }}
    {{ Form::text('fieldname2', Input::old('fieldname2')) }}
    {{-- More fields... --}}
    {{ Form::submit('Save', ['name' => 'submit']) }}
{{ Form::close() }}

So, for example, from a controller, I basically use the same form for creating and updating, like:

// To create a new user
public function create()
    // Load user/createOrUpdate.blade.php view
    return View::make('user.createOrUpdate');

// To update an existing user (load to edit)
public function edit($id)
    $user = User::find($id);
    // Load user/createOrUpdate.blade.php view
    return View::make('user.createOrUpdate')->with('user', $user);

python pandas remove duplicate columns

First step:- Read first row i.e all columns the remove all duplicate columns.

Second step:- Finally read only that columns.

cols = pd.read_csv("file.csv", header=None, nrows=1).iloc[0].drop_duplicates()
df = pd.read_csv("file.csv", usecols=cols)

Wheel file installation

You normally use a tool like pip to install wheels. Leave it to the tool to discover and download the file if this is for a project hosted on PyPI.

For this to work, you do need to install the wheel package:

pip install wheel

You can then tell pip to install the project (and it'll download the wheel if available), or the wheel file directly:

pip install project_name  # discover, download and install
pip install wheel_file.whl  # directly install the wheel

The wheel module, once installed, also is runnable from the command line, you can use this to install already-downloaded wheels:

python -m wheel install wheel_file.whl

Also see the wheel project documentation.

How do I get the total number of unique pairs of a set in the database?

This is how you can approach these problems in general on your own:

The first of the pair can be picked in N (=100) ways. You don't want to pick this item again, so the second of the pair can be picked in N-1 (=99) ways. In total you can pick 2 items out of N in N(N-1) (= 100*99=9900) different ways.

But hold on, this way you count also different orderings: AB and BA are both counted. Since every pair is counted twice you have to divide N(N-1) by two (the number of ways that you can order a list of two items). The number of subsets of two that you can make with a set of N is then N(N-1)/2 (= 9900/2 = 4950).

How to print a dictionary line by line in Python?

You could use the json module for this. The dumps function in this module converts a JSON object into a properly formatted string which you can then print.

import json

cars = {'A':{'speed':70, 'color':2},
        'B':{'speed':60, 'color':3}}

print(json.dumps(cars, indent = 4))

The output looks like

    "A": {
        "color": 2,
        "speed": 70
    "B": {
        "color": 3,
        "speed": 60

The documentation also specifies a bunch of useful options for this method.

Removing multiple files from a Git repo that have already been deleted from disk

For Git 1.x

$ git add -u

This tells git to automatically stage tracked files -- including deleting the previously tracked files.

For Git 2.0

To stage your whole working tree:

$ git add -u :/

To stage just the current path:

$ git add -u .

mysql said: Cannot connect: invalid settings. xampp

I also faced the same problem it was because another mysql service was running and in parallel mysql in xampp i was trying to run. So you may check that out if other solutions don't work out. You can stop that by the following command:

sudo service mysql stop

May help few users.

How can I detect if this dictionary key exists in C#?


 public bool TryGetValue (
    PhysicalAddressKey key,
    out PhysicalAddressEntry physicalAddress

How to switch Python versions in Terminal?

Here is a nice and simple way to do it (but on CENTOS), without braking the operating system.

yum install scl-utils


yum install centos-release-scl-rh

And lastly you install the version that you want, lets say python3.5

yum install rh-python35

And lastly:

scl enable rh-python35 bash

Since MAC-OS is a unix operating system, the way to do it it should be quite similar.

How to validate Google reCAPTCHA v3 on server side?

Check below example

<script src=''></script>

function get_action(form) 
    var v = grecaptcha.getResponse();
    if(v.length == 0)
        document.getElementById('captcha').innerHTML="You can't leave Captcha Code empty";
        return false;
         document.getElementById('captcha').innerHTML="Captcha completed";
        return true; 

<form autocomplete="off" method="post" action=submit.php">

    <input type="text" name="name">
    <input type="text" name="email">
    <div class="g-recaptcha" id="rcaptcha"  data-sitekey="site key"></div>
    <span id="captcha" style="color:red" /></span> <!-- this will show captcha errors -->
    <input type="submit" id="sbtBrn" value="Submit" name="sbt" class="btn btn-info contactBtn" />

Set value of hidden field in a form using jQuery's ".val()" doesn't work

Finally, I have found a solution and it's a simple one:

document.getElementById("texens").value = "tinkumaster";

Works like a charm. No clue why jQuery does not fall back to this.

CSS white space at bottom of page despite having both min-height and height tag

(class/ID):after {

Always works for me class or ID can be for a div or even body causing the white space.

Is it possible to start a shell session in a running container (without ssh)

With docker 1.3, there is a new command docker exec. This allows you to enter a running docker:

docker exec -it "id of running container" bash

Align DIV's to bottom or baseline

The answer posted by Y. Shoham (using absolute positioning) seems to be the simplest solution in most cases where the container is a fixed height, but if the parent DIV has to contain multiple DIVs and auto adjust it's height based on dynamic content, then there can be a problem. I needed to have two blocks of dynamic content; one aligned to the top of the container and one to the bottom and although I could get the container to adjust to the size of the top DIV, if the DIV aligned to the bottom was taller, it would not resize the container but would extend outside. The method outlined above by romiem using table style positioning, although a bit more complicated, is more robust in this respect and allowed alignment to the bottom and correct auto height of the container.


#container {
        display: table;
        height: auto;

#top {
    display: table-cell;
    height: 100%;

#bottom {
    display: table-cell;
    vertical-align: bottom;
    height: 100%;


<div id=“container”>
    <div id=“top”>Dynamic content aligned to top of #container</div>
    <div id=“bottom”>Dynamic content aligned to botttom of #container</div>


I realise this is not a new answer but I wanted to comment on this approach as it lead me to find my solution but as a newbie I was not allowed to comment, only post.

how to check if object already exists in a list

Simple but it works



 if (!MyList.Contains(nextObject))

How to escape a single quote inside awk

Another option is to pass the single quote as an awk variable:

awk -v q=\' 'BEGIN {FS=" ";} {printf "%s%s%s ", q, $1, q}'

Simpler example with string concatenation:

# Prints 'test me', *including* the single quotes.
$ awk -v q=\' '{print q $0 q }' <<<'test me'
'test me'

Should I always use a parallel stream when possible?

A parallel stream has a much higher overhead compared to a sequential one. Coordinating the threads takes a significant amount of time. I would use sequential streams by default and only consider parallel ones if

  • I have a massive amount of items to process (or the processing of each item takes time and is parallelizable)

  • I have a performance problem in the first place

  • I don't already run the process in a multi-thread environment (for example: in a web container, if I already have many requests to process in parallel, adding an additional layer of parallelism inside each request could have more negative than positive effects)

In your example, the performance will anyway be driven by the synchronized access to System.out.println(), and making this process parallel will have no effect, or even a negative one.

Moreover, remember that parallel streams don't magically solve all the synchronization problems. If a shared resource is used by the predicates and functions used in the process, you'll have to make sure that everything is thread-safe. In particular, side effects are things you really have to worry about if you go parallel.

In any case, measure, don't guess! Only a measurement will tell you if the parallelism is worth it or not.

Where does MySQL store database files on Windows and what are the names of the files?

C:\Program Files\MySQL\MySQL Workbench 6.3 CE\sys

paste URLin to window file, and get Tables, Procedures, Functions from this directory

What's wrong with nullable columns in composite primary keys?

Primary keys are for uniquely identifying rows. This is done by comparing all parts of a key to the input.

Per definition, NULL cannot be part of a successful comparison. Even a comparison to itself (NULL = NULL) will fail. This means a key containing NULL would not work.

Additonally, NULL is allowed in a foreign key, to mark an optional relationship.(*) Allowing it in the PK as well would break this.

(*)A word of caution: Having nullable foreign keys is not clean relational database design.

If there are two entities A and B where A can optionally be related to B, the clean solution is to create a resolution table (let's say AB). That table would link A with B: If there is a relationship then it would contain a record, if there isn't then it would not.

How to make overlay control above all other controls?

If you are using a Canvas or Grid in your layout, give the control to be put on top a higher ZIndex.

From MSDN:

<Page xmlns="" WindowTitle="ZIndex Sample">
    <Rectangle Canvas.ZIndex="3" Width="100" Height="100" Canvas.Top="100" Canvas.Left="100" Fill="blue"/>
    <Rectangle Canvas.ZIndex="1" Width="100" Height="100" Canvas.Top="150" Canvas.Left="150" Fill="yellow"/>
    <Rectangle Canvas.ZIndex="2" Width="100" Height="100" Canvas.Top="200" Canvas.Left="200" Fill="green"/>

    <!-- Reverse the order to illustrate z-index property -->

    <Rectangle Canvas.ZIndex="1" Width="100" Height="100" Canvas.Top="300" Canvas.Left="200" Fill="green"/>
    <Rectangle Canvas.ZIndex="3" Width="100" Height="100" Canvas.Top="350" Canvas.Left="150" Fill="yellow"/>
    <Rectangle Canvas.ZIndex="2" Width="100" Height="100" Canvas.Top="400" Canvas.Left="100" Fill="blue"/>

If you don't specify ZIndex, the children of a panel are rendered in the order they are specified (i.e. last one on top).

If you are looking to do something more complicated, you can look at how ChildWindow is implemented in Silverlight. It overlays a semitransparent background and popup over your entire RootVisual.

Passing parameters to JavaScript files

I think it is far more better and modern solution to just use localStorage on the page where the javascript is included and then just re-use it inside the javascript itself. Set it in localStorage with:

localStorage.setItem("nameOfVariable", "some text value");

and refer to it inside javascript file like:


Setting the default Java character encoding

I have a hacky way that definitely works!!

Field charset = Charset.class.getDeclaredField("defaultCharset");

This way you are going to trick JVM which would think that charset is not set and make it to set it again to UTF-8, on runtime!

fatal: git-write-tree: error building trees

maybe there are some unmerged paths in your git repository that you have to resolve before stashing.

Can't push image to Amazon ECR - fails with "no basic auth credentials"

I faced the same issue and the mistake I did was using the wrong repo path

eg: docker push

In the above path this is where I've done the mistake: In "" instead of "west". I was using "east". Once I corrected my mistake, I was able to push the image successfully.

Easy way to export multiple data.frame to multiple Excel worksheets

For me, WriteXLS provides the functionality you are looking for. Since you did not specify which errors it returns, I show you an example:


x <- list(sheet_a = data.frame(a=letters), sheet_b = data.frame(b = LETTERS))
WriteXLS(x, "test.xlsx", names(x))


If x is:

  • a list of data frames, each one is written to a single sheet
  • a character vector (of R objects), each object is written to a single sheet
  • something else, then see also what the help states:

More on usage



`x`: A character vector or factor containing the names of one or
     more R data frames; A character vector or factor containing
     the name of a single list which contains one or more R data
     frames; a single list object of one or more data frames; a
     single data frame object.


For your example, you would need to collect all data.frames in a list during the loop, and use WriteXLS after the loop has finished.

Session info

  • R 3.2.4
  • WriteXLS 4.0.0

Jinja2 shorthand conditional

Yes, it's possible to use inline if-expressions:

{{ 'Update' if files else 'Continue' }}

Trim spaces from start and end of string

ECMAScript 5 supports trim and this has been implemented in Firefox.

trim - MDC

Init array of structs in Go

You can have it this way:

It is important to mind the commas after each struct item or set of items.

earnings := []LineItemsType{


            TypeName: "Earnings",

            Totals: 0.0,

            HasTotal: true,

            items: []LineItems{


                    name: "Basic Pay",

                    amount: 100.0,


                    name: "Commuter Allowance",

                    amount: 100.0,

            TypeName: "Earnings",

            Totals: 0.0,

            HasTotal: true,

            items: []LineItems{


                    name: "Basic Pay",

                    amount: 100.0,


                    name: "Commuter Allowance",

                    amount: 100.0,

How to use __doPostBack()

Old question, but I'd like to add something: when calling doPostBack() you can use the server handler method for the action.

For an example:

__doPostBack('<%= btn.UniqueID%>', 'my args');

Will fire, on server:

protected void btn_Click(object sender, EventArgs e)

I didn't find a better way to get the argument, so I'm still using Request["__EVENTARGUMENT"].

Git Push error: refusing to update checked out branch

Reason:You are pushing to a Non-Bare Repository

There are two types of repositories: bare and non-bare

Bare repositories do not have a working copy and you can push to them. Those are the types of repositories you get in Github! If you want to create a bare repository, you can use

git init --bare

So, in short, you can't push to a non-bare repository (Edit: Well, you can't push to the currently checked out branch of a repository. With a bare repository, you can push to any branch since none are checked out. Although possible, pushing to non-bare repositories is not common). What you can do, is to fetch and merge from the other repository. This is how the pull request that you can see in Github works. You ask them to pull from you, and you don't force-push into them.

Update: Thanks to VonC for pointing this out, in the latest git versions (currently 2.3.0), pushing to the checked out branch of a non-bare repository is possible. Nevertheless, you still cannot push to a dirty working tree, which is not a safe operation anyway.

caching JavaScript files

In your Apache .htaccess file:

#Create filter to match files you want to cache 
<Files *.js>
Header add "Cache-Control" "max-age=604800"

I wrote about it here also:

Warning as error - How to get rid of these

View -> Error list -> Right click on specific Error/Warning.

You can change Severity as You want.

How to empty a char array?

Use bzero(array name, no.of bytes to be cleared);

Expand a random range from 1–5 to 1–7

I know it has been answered, but is this seems to work ok, but I can not tell you if it has a bias. My 'testing' suggests it is, at least, reasonable.

Perhaps Adam Rosenfield would be kind enough to comment?

My (naive?) idea is this:

Accumulate rand5's until there is enough random bits to make a rand7. This takes at most 2 rand5's. To get the rand7 number I use the accumulated value mod 7.

To avoid the accumulator overflowing, and since the accumulator is mod 7 then I take the mod 7 of the accumulator:

(5a + rand5) % 7 = (k*7 + (5a%7) + rand5) % 7 = ( (5a%7) + rand5) % 7

The rand7() function follows:

(I let the range of rand5 be 0-4 and rand7 is likewise 0-6.)

int rand7(){
  static int    a=0;
  static int    e=0;
  int       r;
  a = a * 5 + rand5();
  e = e + 5;        // added 5/7ths of a rand7 number
  if ( e<7 ){
    a = a * 5 + rand5();
    e = e + 5;  // another 5/7ths
  r = a % 7;
  e = e - 7;        // removed a rand7 number
  a = a % 7;
  return r;

Edit: Added results for 100 million trials.

'Real' rand functions mod 5 or 7

rand5 : avg=1.999802 0:20003944 1:19999889 2:20003690 3:19996938 4:19995539 rand7 : avg=3.000111 0:14282851 1:14282879 2:14284554 3:14288546 4:14292388 5:14288736 6:14280046

My rand7

Average looks ok and number distributions look ok too.

randt : avg=3.000080 0:14288793 1:14280135 2:14287848 3:14285277 4:14286341 5:14278663 6:14292943

What does "exec sp_reset_connection" mean in Sql Server Profiler?

It's an indication that connection pooling is being used (which is a good thing).

How to convert timestamp to datetime in MySQL?

SELECT from_unixtime( UNIX_TIMESTAMP(fild_with_timestamp) ) from "your_table"
This work for me

Show "loading" animation on button click

I know this a very much late reply but I saw this query recently And found a working scenario,

OnClick of Submit use the below code:

 $('#Submit').click(function ()
 { $(this).html('<img src="icon-loading.gif" />'); // A GIF Image of Your choice
 return false });

To Stop the Gif use the below code:


How do I properly force a Git push?

This was our solution for replacing master on a corporate gitHub repository while maintaining history.

push -f to master on corporate repositories is often disabled to maintain branch history. This solution worked for us.

git fetch desiredOrigin
git checkout -b master desiredOrigin/master // get origin master

git checkout currentBranch  // move to target branch
git merge -s ours master  // merge using ours over master
// vim will open for the commit message
git checkout master  // move to master
git merge currentBranch  // merge resolved changes into master

push your branch to desiredOrigin and create a PR

How do I insert non breaking space character &nbsp; in a JSF page?

Not necessary to give 160 . 141 will also work. For the value field provide value="&#141" .

Does Typescript support the ?. operator? (And, what's it called?)

The Elvis (?.) Optional Chaining Operator is supported in TypeScript 3.7.

You can use it to check for null values: cats?.miows returns null if cats is null or undefined.

You can also use it for optional method calling: cats.doMiow?.(5) will call doMiow if it exists.

Property access is also possible: cats?.['miows'].


node.js, with SSL

This is my nginx config file and iosocket code. Server(express) is listening on port 9191. It works well: nginx config file:

server {
    listen       443 ssl;
    server_name  localhost;
    root   /usr/share/nginx/html/rdist;

    location /user/ {
        proxy_pass   http://localhost:9191;
    location /api/ {
        proxy_pass   http://localhost:9191;
    location /auth/ {
        proxy_pass   http://localhost:9191;

    location / {
        index  index.html index.htm;
        if (!-e $request_filename){
          rewrite ^(.*)$ /index.html break;
    location / {
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_pass   http://localhost:9191/;

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;

    ssl_certificate /etc/nginx/conf.d/sslcert/xxx.pem;
    ssl_certificate_key /etc/nginx/conf.d/sslcert/xxx.key;



const server = require('http').Server(app)
const io = require('')(server)
io.on('connection', (socket) => {

  socket.on("disconnect", () => {

server.listen(9191, function () {
  console.log('Server listening on port 9191')


    const socket = io.connect('', { secure: true, query: `userId=${this.props.user._id}` })

        socket.on('notifications', data => {
            console.log('Get messages from back end:', data)

How to send post request to the below post method using postman rest client

1.Open postman app 2.Enter the URL in the URL bar in postman app along with the name of the design.Use slash(/) after URL to give the design name. 3.Select POST from the dropdown list from URL textbox. 4.Select raw from buttons available below the URL textbox. 5.Select JSON from the dropdown. 6.In the text area enter your data to be updated and enter send. 7.Select GET from dropdown list from URL textbox and enter send to see the updated result.

Conditional Count on a field

IIF is not a standard SQL construct, but if it's supported by your database, you can achieve a more elegant statement producing the same result:

SELECT JobId, JobName,

COUNT(IIF (Priority=1, 1, NULL)) AS Priority1,
COUNT(IIF (Priority=2, 1, NULL)) AS Priority2,
COUNT(IIF (Priority=3, 1, NULL)) AS Priority3,
COUNT(IIF (Priority=4, 1, NULL)) AS Priority4,
COUNT(IIF (Priority=5, 1, NULL)) AS Priority5

FROM TableName
GROUP BY JobId, JobName

Detect element content changes with jQuery

We can achieve this by using Mutation Events. According to, The mutation event module is designed to allow notification of any changes to the structure of a document, including attr and text modifications. For more detail MUTATION EVENTS

For Example :

$("body").on('DOMSubtreeModified', "#content", function() {
    alert('Content Modified'); // do something

Select DataFrame rows between two dates

You can also use between:

df[df.some_date.between(start_date, end_date)]

Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

Neither the question nor the answers really fit my simple way of thinking about it. I'm a consultant and have synchronized these definitions with a number of Dev teams and DevOps people, but am curious about how it matches with the industry at large:

Basically I think of the agile practice of continuous delivery like a continuum:

Not continuous (everything manual) 0% ----> 100% Continuous Delivery of Value (everything automated)

Steps towards continuous delivery:

Zero. Nothing is automated when devs check in code... You're lucky if they have compiled, run, or performed any testing prior to check-in.

  1. Continuous Build: automated build on every check-in, which is the first step, but does nothing to prove functional integration of new code.

  2. Continuous Integration (CI): automated build and execution of at least unit tests to prove integration of new code with existing code, but preferably integration tests (end-to-end).

  3. Continuous Deployment (CD): automated deployment when code passes CI at least into a test environment, preferably into higher environments when quality is proven either via CI or by marking a lower environment as PASSED after manual testing. I.E., testing may be manual in some cases, but promoting to next environment is automatic.

  4. Continuous Delivery: automated publication and release of the system into production. This is CD into production plus any other configuration changes like setup for A/B testing, notification to users of new features, notifying support of new version and change notes, etc.

EDIT: I would like to point out that there's a difference between the concept of "continuous delivery" as referenced in the first principle of the Agile Manifesto ( and the practice of Continuous Delivery, as seems to be referenced by the context of the question. The principle of continuous delivery is that of striving to reduce the Inventory waste as described in Lean thinking ( The practice of Continuous Delivery (CD) by agile teams has emerged in the many years since the Agile Manifesto was written in 2001. This agile practice directly addresses the principle, although they are different things and apparently easily confused.

AngularJS: How can I pass variables between controllers?

Second Approach :

angular.module('myApp', [])
  .controller('Ctrl1', ['$scope',
    function($scope) {

    $scope.prop1 = "First";

    $scope.clickFunction = function() {
      $scope.$broadcast('update_Ctrl2_controller', $scope.prop1);
.controller('Ctrl2', ['$scope',
    function($scope) {
      $scope.prop2 = "Second";

        $scope.$on("update_Ctrl2_controller", function(event, prop) {
        $scope.prop = prop;

        $scope.both = prop + $scope.prop2; 

Html :

<div ng-controller="Ctrl2">

<button ng-click="clickFunction()">Click</button>

For more details see plunker :

generating variable names on fly in python

Though I don't see much point, here it is:

for i in xrange(0, len(prices)):
    exec("price%d = %s" % (i + 1, repr(prices[i])));

Clear History and Reload Page on Login/Logout Using Ionic Framework

As pointed out by @ezain reload controllers only when its necessary. Another cleaner way of updating data when changing states rather than reloading the controller is using broadcast events and listening to such events in controllers that need to update data on views.

Example: in your login/logout functions you can do something like so:

$scope.login = function(){
    //After login logic then send a broadcast
$scope.logout = function(){
   //After logout logic then send a broadcast

Now in your mainPage controller trigger the changes in the view by using the $on function to listen to broadcast within the mainPage Controller like so:

$scope.$on("user-logged-in", function(){
     //update mainPage view data here eg. $scope.username = 'John';

$scope.$on("user-logged-out", function(){
    //update mainPage view data here eg. $scope.username = '';

Opening a remote machine's Windows C drive

By default, Windows makes the root of each drive available (provided you've got Administrator privileges) as (e.g.) \\server\c$. These are known as Administrative Shares.

How to increase the gap between text and underlining in CSS

Here is what works well for me.

<style type="text/css">_x000D_
  #underline-gap {_x000D_
    text-decoration: underline;_x000D_
    text-underline-position: under;_x000D_
  <h1 id="underline-gap"><a href="">Google</a></h1>_x000D_

MySQL - sum column value(s) based on row from the same table

I think you're making this a bit more complicated than it needs to be.

    SUM(IF(PaymentMethod = 'Cash', Amount, 0)) AS 'Cash',
    -- snip
    SUM(Amount) AS Total
    SaleDate = '2012-02-10'

How to re-create database for Entity Framework?

Just want to add to the excellent answer of @Lin:

5) B. If you don't have SQL Management Studio, go to "SQL Server Object Explorer". If you cannot see your project db in the localdb "SQL Server Object Explorer", then click on "Add SQL server" button to add it to the list manually. Then you can delete the db from the list.

External VS2013 build error "error MSB4019: The imported project <path> was not found"

In my case I was using the wrong version of MSBuild.exe.

The version you need to use depends on what version of Visual Studio you used to create your project. In my case I needed 14.0 (having used Visual Studio 2015).

This was found at:

C:\Program Files (x86)\MSBuild\14.0\Bin\msbuild.exe

You can look under:

C:\Program Files (x86)\MSBuild

To find other versions.

Basic example for sharing text or image with UIActivityViewController in Swift

I've used the implementation above and just now I came to know that it doesn't work on iPad running iOS 13. I had to add these lines before present() call in order to make it work

//avoiding to crash on iPad
if let popoverController = activityViewController.popoverPresentationController {
     popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
     popoverController.sourceView = self.view
     popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)

That's how it works for me

func shareData(_ dataToShare: [Any]){

        let activityViewController = UIActivityViewController(activityItems: dataToShare, applicationActivities: nil)

        //exclude some activity types from the list (optional)
        //activityViewController.excludedActivityTypes = [

        //avoiding to crash on iPad
        if let popoverController = activityViewController.popoverPresentationController {
            popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
            popoverController.sourceView = self.view
            popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)

        self.present(activityViewController, animated: true, completion: nil)

Reading HTML content from a UIWebView

I use a swift extension like this:

extension UIWebView {
    var htmlContent:String? {
        return self.stringByEvaluatingJavaScript(from: "document.documentElement.outerHTML")


How can I keep my branch up to date with master with git?

You can use the cherry-pick to get the particular bug fix commit(s)

$ git checkout branch
$ git cherry-pick bugfix

Bootstrap Align Image with text

I think this is helpful for you

<div class="container">
        <div class="page-header">
                <h1>About Me</h1>
            </div><!--END page-header-->
        <div class="row" id="features">
                <div class="col-sm-6 feature">
                        <img src="" alt="Web Design" class="img-circle">
                </div><!--END feature-->

                <div class="col-sm-6 feature">
                        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,</p>
                </div><!--END feature-->
            </div><!--end features-->
    </div><!--end container-->

Java Constructor Inheritance

Because constructing your subclass object may be done in a different way from how your superclass is constructed. You may not want clients of the subclass to be able to call certain constructors available in the superclass.

A silly example:

class Super {
    protected final Number value;
    public Super(Number value){
        this.value = value;

class Sub {
    public Sub(){ super(Integer.valueOf(0)); }
    void doSomeStuff(){
        // We know this.value is an Integer, so it's safe to cast.

// Client code:
Sub s = new Sub(Long.valueOf(666L)): // Devilish invocation of Super constructor!
s.doSomeStuff(); // throws ClassCastException

Or even simpler:

class Super {
    private final String msg;
    Super(String msg){
        if (msg == null) throw new NullPointerException();
        this.msg = msg;
class Sub {
    private final String detail;
    Sub(String msg, String detail){
        if (detail == null) throw new NullPointerException();
        this.detail = detail;
    void print(){
        // detail is never null, so this method won't fail
        System.out.println(detail.concat(": ").concat(msg));
// Client code:
Sub s = new Sub("message"); // Calling Super constructor - detail is never initialized!
s.print(); // throws NullPointerException

From this example, you see that you'd need some way of declaring that "I want to inherit these constructors" or "I want to inherit all constructors except for these", and then you'd also have to specify a default constructor inheritance preference just in case someone adds a new constructor in the superclass... or you could just require that you repeat the constructors from the superclass if you want to "inherit" them, which arguably is the more obvious way of doing it.

Linq where clause compare only date value without time value

There is also EntityFunctions.TruncateTime or DbFunctions.TruncateTime in EF 6.0

Mean filter for smoothing images in Matlab

I see good answers have already been given, but I thought it might be nice to just give a way to perform mean filtering in MATLAB using no special functions or toolboxes. This is also very good for understanding exactly how the process works as you are required to explicitly set the convolution kernel. The mean filter kernel is fortunately very easy:

I = imread(...)
kernel = ones(3, 3) / 9; % 3x3 mean kernel
J = conv2(I, kernel, 'same'); % Convolve keeping size of I

Note that for colour images you would have to apply this to each of the channels in the image.