Tutorial by Examples: ev

Most times when people have to reverse a string, they do it more or less like this: char[] a = s.ToCharArray(); System.Array.Reverse(a); string r = new string(a); However, what these people don't realize is that this is actually wrong. And I don't mean because of the missing NULL check. It ...

Custom events usually need custom event arguments containing information about the event. For example MouseEventArgs which is used by mouse events like MouseDown or MouseUp events, contains information about Location or Buttons which used to generate the event. When creating new events, to create a...

A cancelable event can be raised by a class when it is about to perform an action that can be canceled, such as the FormClosing event of a Form. To create such event: Create a new event arg deriving from CancelEventArgs and add additional properties for event data. Create an event using EventH...

In javascript, assigning a non-primitive value (Such as Object, Array, Function, and many more), keeps a reference (an address in the memory) to the assigned value. Assigning a primitive value (String, Number, Boolean, or Symbol) to two different variables, and changing one, won't change both: var...

RewriteEngine on RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://(www\.)?yourdomain.com/.*$ [NC] RewriteRule \.(gif|jpg|css)$ - [F] This blocks all the links to '.gif', '.jpg' and '.css' files which are not from the domain name http://www.yourdomain.com. Display alterna...

You can use any ruby technique to dynamically create a list of files to load. Illustration of globbing for files starting with test, loaded in alphabetical order. Dir[ "#{ __dir__ }**/test*.rb" ) ].sort.each do |source| require_relative source end

Visual Studio Code is an open-source and feature-rich code editor from Microsoft. To set it up it for NativeScript development, open the Command Palette (F1 or ⌘+Shift+P) and type ext install NativeScript. Once the NativeScript extension is installed, the debugger should allow you to set breakpoint...

Enable USB Debugging on your device and from command line type adb devices. If everything is OK, the response should be: List of devices attached 1234567890 device Where 1234567890 is the device's id. If multiple devices are connected, you should see all of them: List of devices at...

A whole circle is 360 degrees or Math.PI * 2 radians. Half of those values follows to be 180 degrees or Math.PI radians. A quarter is then 90 degrees or Math.PI / 2 radians. To get a segment as a percentage of a whole circle in radians: function getSegment(percent:Number):Number { retur...

A string can reversed using the built-in reversed() function, which takes a string and returns an iterator in reverse order. >>> reversed('hello') <reversed object at 0x0000000000000000> >>> [char for char in reversed('hello')] ['o', 'l', 'l', 'e', 'h'] reversed() can ...

Sometimes you may only need to simulate an event with two outcomes, maybe with different probabilities, but you may find yourself in a situation that calls for many possible outcomes with different probabilities. Let's imagine you want to simulate an event that has six equally probable outcomes. T...

The slider provides an event called slide that will trigger whenever the mouse moves during a slider handle drag. This function holds a reference to the slide event and a reference to the slider ui object. The ui object holds a jQuery object for the handle being moved and the value(s) of the slide...

The slider provides an event called change that will trigger after the mouse completes a slider handle drag or if the value(s) have been changed programmatically. This function holds a reference to the slide event and a reference to the slider ui object. The ui object holds a jQuery object for the ...

SELECT ps.name AS PartitionScheme , fg.name AS [FileGroup] , prv.* , LAG(prv.Value) OVER (PARTITION BY ps.name ORDER BY ps.name, boundary_id) AS PreviousBoundaryValue FROM sys.partition_schemes ps INNER JOIN sys.destination_data...

CREATE VIEW view_EmployeeInfo AS SELECT EmployeeID, FirstName, LastName, HireDate FROM Employee GO Rows from views can be selected much like tables: SELECT FirstName FROM view_EmployeeInfo You may also create a view with a calculated column. We can...

CREATE VIEW view_EmployeeInfo WITH ENCRYPTION AS SELECT EmployeeID, FirstName, LastName, HireDate FROM Employee GO

CREATE VIEW view_PersonEmployee AS SELECT P.LastName, P.FirstName, E.JobTitle FROM Employee AS E INNER JOIN Person AS P ON P.BusinessEntityID = E.BusinessEntityID GO Views can use joins to select data from numerous sources like tables, table functio...

The vast majority of modern JavaScript environments work according to an event loop. This is a common concept in computer programming which essentially means that your program continually waits for new things to happen, and when they do, reacts to them. The host environment calls into your program, ...

Many interesting operations in common JavaScript programming environments are asynchronous. For example, in the browser we see things like window.setTimeout(() => { console.log("this happens later"); }, 100); and in Node.js we see things like fs.readFile("file.txt", (...

Open a text editor (like Notepad), and type the code below: Imports System.ComponentModel Imports System.Drawing Imports System.Windows.Forms Namespace SampleApp Public Class MainForm : Inherits Form Private btnHello As Button ' The form's constructor: thi...