Compiler Error CS0218
The type ('type') must contain declarations of operator true and operator false
If you define an operator for a user-defined type, and then try to use the operator as a short-circuit operator, the user-defined operator must have operator true and operator false defined. For more information on short-circuit operators, see && Operator and || Operator.
The following sample generates CS0218:
// CS0218.cs
using System;
public class MyClass
{
// uncomment these operator declarations to resolve this CS0218
/*
public static bool operator true (MyClass f)
{
return false;
}
public static bool operator false (MyClass f)
{
return false;
}
*/
public static implicit operator int(MyClass x)
{
return 0;
}
public static MyClass operator & (MyClass f1, MyClass f2)
{
return new MyClass();
}
public static void Main()
{
MyClass f = new MyClass();
int i = f && f; // CS0218, requires operators true and false
}
}