Types that are value types but can hold a null value also apart from the normal range of integer values e.g. Nullable, pronounced "Nullable of Int32," can be assigned any value from -2147483648 to 2147483647, or it can be assigned the null value. A Nullable can be assigned the values true or false, or null.
Nullable types are instances of the System.Nullable struct.
Declaration:-
int? i
or
Nullable i;
Examples:-
In example below HasValue returns true if object is not null.
int? num = null;
if (num.HasValue == true)
{
System.Console.WriteLine("num = " + num.Value);
}
else
{
System.Console.WriteLine("num = Null");
}
To give default value or null use
int y = num.GetValueOrDefault();
Besides this the Value property returns a value if one is assigned, otherwise a System.InvalidOperationException is thrown
Prior to .Net 2.0 there was a huge gap between database types and c# types e.g. for an int value we can have null in database but in c# int or we can say value types couldn't hold null values..Net 2.0 was the first step towards bridging this gap and it did by introducing nullable types i.e.
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