Why are C macros not type-safe?

Question

If have encountered this claim multiple times and can\'t figure out what it is supposed to mean. Since the resulting code is compiled using a regular C compiler it will end up b

Answer 1

There are situations where macros are even less type-safe than functions. E.g.

void printlog(int iter, double obj)
{
    printf("%.3f at iteration %d\n", obj, iteration);
}

Calling this with the arguments reversed will cause truncation and erroneous results, but nothing dangerous. By contrast,

#define PRINTLOG(iter, obj) printf("%.3f at iteration %d\n", obj, iter)

causes undefined behavior. To be fair, GCC warns about the latter, but not about the former, but that's because it knows printf -- for other varargs functions, the results are potentially disastrous.