Why String is Value type although it is a class not a struct?

Take the following example:

string me = "Ibraheem";
string copy = me;
me = "Empty";
Console.WriteLine(me);
Console.WriteLine(copy);

The output is:

Empty
Ibraheem

Since it is class type (i.e. not a struct), String copy should also contain Empty because the = operator in C# assigns reference of objects rather than the object itself (as in C++)??