Using Nullable Types

http://msdn2.microsoft.com/en-us/library/2cf62fcy(VS.80).aspx
Examples of Nullable Types

Any value type may be used as the basis for a nullable type. For example:

int? i = 10;
double? d1 = 3.14;
bool? flag = null;
char? letter = 'a';
int?[] arr = new int?[10];