Compiler Error CS0077

The as operator must be used with a reference type or nullable type ('int' is a non-nullable value type).

The as operator was passed a value type. Because as can return null, it can only be passed a reference type or a nullable value type.

The following sample generates CS0077:

// CS0077.cs  
using System;  
class C  
struct S  
class M  
   public static void Main()  
      object o1, o2;  
      C c;  
      S s;  
      o1 = new C();  
      o2 = new S();  
      s = o2 as S;  
      // CS0077, S is not a reference type.  
      // Try the following line instead.  
      // c = o1 as C;