?? Operator in C#

The ?? operator is called the null-coalescing operator and is used to define a default value for nullable value types or reference types. It returns the left-hand operand if the operand is not null; otherwise it returns the right operand.

A nullable type can contain a value, or it can be undefined. The ?? operator defines the default value to be returned when a nullable type is assigned to a non-nullable type. If you try to assign a nullable value type to a non-nullable value type without using the ?? operator, you will generate a compile-time error. If you use a cast, and the nullable value type is currently undefined, an InvalidOperationException exception will be thrown.

int? x = null;
// y = x, unless x is null, in which case y = -1. 
int y = x ?? -1;

Useful links

Nullable Types

?? Operator

The C# ?? null coalescing operator (and using it with LINQ)

Windows Keyboard Shortcuts

Calculator Keyboard Shortcuts

Press this key	To do this
Press this key Alt+1	To do this Switch to Standard mode
Press this key Alt+2	To do this Switch to Scientific mode
Press this key Alt+3	To do this Switch to Programmer mode
Press this key Alt+4	To do this Switch to Statistics mode
Press this key Ctrl+E	To do this Open date calculations
Press this key Esc	To do this Press the C button

Full list is available here
http://windows.microsoft.com/en-gb/windows/keyboard-shortcuts#keyboard-shortcuts=windows-7

Visual Studio Keyboard Shortcuts

A good collection of keyboard shortcuts for Visual studio is available @ http://www.shortcutworld.com/en/win/Visual-Studio_2010.html

Unit Testing JavaScript

What is QUnit?

QUnit is a powerful, easy-to-use JavaScript unit testing framework.

Getting Started

A minimal QUnit test setup:

<!DOCTYPE html>
<html:gt;
<head:gt;
<meta charset="utf-8">
<title>QUnit Example</title>
<link rel="stylesheet" href="/resources/qunit.css">
</head>
<body>
<div id="qunit"></div>
<div id="qunit-fixture"></div>
<script src="/resources/qunit.js"></script>
<script src="/resources/tests.js"></script>
</body>
</html>

The contents of tests.js:

test( "hello test", function() {
  ok( 1 == "1", "Passed!" );
});

Useful links

qunitjs.com

http://qunitjs.com/intro/

How to open link in a new tab in iPad

To open a link in a new tab, long-press that link. Choose the command "Open in New Tab" from the menu that appears.

How to force links in Blogger to open In New Tab

By default, all links and hyperlinks in Blogger opens in your current window. To change this behavior follow these steps

1. Login to your Blogger account
2. Navigate to TEMPLATE > Edit HTML
3. Search for the tag in your template’s code. Hint: Use Ctrl+F to find the code.
4. Copy the code below and Paste it below the tag

   <base target='_blank'/>

5. Hit the "save template" button and you are done.

Cookies: Frequently Asked Questions

What is a cookie?

A cookie is a piece of information in the form of a very small text file that is placed on an internet user's hard drive. It is generated by a web page server, which is basically the computer that operates a web site. The information the cookie contains is set by the server and it can be used by that server whenever the user visits the site. A cookie can be thought of as an internet user's identification card, which tell a web site when the user has returned.

History of cookies

Cookies for the internet were originally developed in 1995 by the Netscape Communications Corporation. The word 'cookie' comes from 'magic cookie,' a term in programming languages for a piece of information shared between co-operating pieces of software. The choice of the word cookie appears to come from the American tradition of giving and sharing edible cookies.

What is the purpose of cookies?

Cookies make the interaction between users and web sites faster and easier. Without cookies, it would be very difficult for a web site to allow a visitor to fill up a shopping cart or to remember the user's preferences or registration details for a future visit.

Web sites use cookies mainly because they save time and make the browsing experience more efficient and enjoyable.

Web sites often use cookies for the purposes of collecting demographic information about their users.

Cookies enable web sites to monitor their users' web surfing habits and profile them for marketing purposes (for example, to find out which products or services they are interested in and send them targeted advertisements).

Are there different types of cookies?

Cookies come in different flavours: Session, or transient cookies

Session cookies

Cookies that are stored in the computer's memory only during a user's browsing session and are automatically deleted from the user's computer when the browser is closed.

These cookies usually store a session ID that is not personally identifiable to users, allowing the user to move from page to page without having to log-in repeatedly. They are widely used by commercial web sites (for example, to keep track of items that a consumer has added to a shopping cart).

Session cookies are never written on the hard drive and they do not collect any information from the user's computer. Session cookies expire at the end of the user's browser session and can also become no longer accessible after the session has been inactive for a specified length of time, usually 20 minutes.

Permanent, persistent, or stored cookies

Cookies that are stored on the user's computer and are not deleted when the browser is closed. Permanent cookies can retain user preferences for a particular web site, allowing those preferences to be used in future browsing sessions.

Permanent cookies can be used to identify individual users, so they may be used by web sites to analyse users' surfing behaviour within the web site. These cookies can also be used to provide information about numbers of visitors, the average time spent on a particular page and generally the performance of the web site. They are usually configured to keep track of users for a prolonged period of time, in some cases many years into the future.

Find out more