A string is null if it has not been assigned a value (in C++ and Visual Basic) or if has explicitly been assigned a value of null. Although the composite formatting feature can gracefully handle a null string, as the following example shows, attempting to call one if its members throws a NullReferenceException.
A string is empty if it is explicitly assigned an empty string ("") or String.Empty. An empty string has a Length of 0. The following example creates an empty string and displays its value and its length.
Universal Windows Platform Available since 8 .NET Framework Available since 2.0 Portable Class Library Supported in: portable .NET platforms Silverlight Available since 2.0 Windows Phone Silverlight Available since 7.0 Windows Phone Available since 8.1