(C#) Null Coalescing Operator (setting default variable values)

by Matt on 2009/10/22 at 7:00 am

Prerequisites: Basic knowledge of variables and assigning values.

The purpose of the Null Coalescing Operator ( ?? ) is to set a default value for a variable in the event the first value you are attempting to assign from is null. Hence, the logic behind the null coalescing operator is this: If this variable is null, use this other value instead.

This is handy is because what would otherwise be a multiple-line if/else block is now a single, concise line.

v Scenario

Let’s say you want the value of a string called strCurrentName to be set the same as the value of another string called strPreviousName, but you know that there’s a chance that strPreviousName could be null and if it is you simply want to give strPreviousName a valued of “No Name Entered”.

What you would do is this

C#:

/*
Here we'd prefer to use strCustomerName, but there's a chance it may be null SO...
if strCustomerName is null, then strCurrentName gets "Name Unknown" instead.
*/
string strCurrentName = strCustomerName ?? "Name Unknown";

• Posted under Toolbox and tagged with @Complexity: Beginner, ASP.NET, C#

(C#) Null Coalescing Operator (setting default variable values)

v Scenario

No Comments

Post a Comment