C# 0 The Complete Reference

int

 and 

bool

 type:

int? count;

bool? done;

When using nullable types, you will often see a nullable object created like this:

int? count = null;

This explicitly initializes 

count

 to 

null

. This satisfies the constraint that a variable must be 

given a value before it is used. In this case, the value simply means undefined.

You can assign a value to a nullable variable in the normal way because a conversion 

from the underlying type to the nullable type is predefined. For example, this assigns the 

value 100 to 

count

.

count = 100;

There are two ways to determine if a variable of a nullable type is 

null

 or contains a 

value. First, you can test its value against