Type.GetEnumUnderlyingType Method ()
Returns the underlying type of the current enumeration type.
Assembly: mscorlib (in mscorlib.dll)
The current type is not an enumeration.
The enumeration type is not valid, because it contains more than one instance field.
By default, the underlying type of an enumeration in C# and Visual Basic is Int32. Other integer types can be specified.
Available since 4.0