Compiler Error C2083

struct/union comparison illegal

A structure or union was directly compared with another user-defined type.

A user-defined type cannot be compared with another user-defined type unless a comparison operator has been defined or a conversion to a scalar type exists.

The following is an example of this error:

struct A
{
   int i;
} a, b;
void func()
{
   if( a == b );   // error, structure comparison
}