Saturday, July 07, 2007

What is Nullable Type in .Net 2.0?

What is Nullable Type in .Net 2.0?
Nullable in .Net 2.0, helps to determine whether variable has been assigned a value or not. Example: Quiz application having option yes/no, but it should displayed “Not Attempted” when user does not make any choice.

Declaring a variable as nullable enables the HasValue and Value members.

Nullable b = null; -OR-

// Shorthand notation for declaring nullable type, only for C#
bool? b = null;


Example of Nullable Type
Use HasValue to detect whether or not a value has been set:
if (b.HasValue)
Console.WriteLine("User has Attempted Given Question");
else
Console.WriteLine("User has not Attempted Given Question");

//Output
User has not Attempted Given Question

The Nullable type is a new feature in .NET 2.0.

1 comment:

Anonymous said...

I want to add some more in this useful blog :-

Nullable types have 2 read-only properties hasvalue which returns whether the instance is null or not and value which returns the value where hasvalue is true.

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