Indicates whether the current instance contains a value.
true if the current instance contains a value; otherwise false.
If Nullable<T>.HasValue is true, the instance contains a value, and Nullable<T>.Value returns that value.
If Nullable<T>.HasValue is false, the instance contains no value, and an attempt to read Nullable<T>.Value results in a InvalidOperationExceptionexception. A call to Nullable<T>.Value.GetValueOrDefault returns the default value.
This property is read-only.