Compile-time assertion?

Question

Is there a way I can assert that two constant expressions are equal at compile time?

e.g. I want this to cause a compile-time error

enum { foo=263,          


        

Answer 1

For another version of a static assert, that you can glorify by adding a better name, you can use:

// name must be a valid identifier
#define STATIC_ASSERT( condition, name )\
    typedef char assert_failed_ ## name [ (condition) ? 1 : -1 ];

And use as:

STATIC_ASSERT( x == y, constants_must_be_same );

The compiler will trigger an error similar to:

size of array 'assert_failed_constants_must_be_same' is negative

Which does not seem that helpful, but it will point to the exact line of the assert, and after a while you will start processing that error message as static assert failed