Comparing void pointers

Tillotson

I want to find if the two values are equal, here's what I've done so far which compares byte by byte:

 21 int cmp_void (void *a, void *b, size_t sz) {
 22         size_t i;
 23         for (i = 0; i < sz; i++) {
 24                 if (*(char *)(a + i) != *(char *)(b + i)) {
 25                         return 0;
 26                 }
 27         }
 28         return 1;
 29 }

Seems to work but I'm wondering if there is a better way which doesn't throw compiler warnings.

mylist.c:24: warning: pointer of type 'void *' used in arithmetic

thanks

padraig_f

I think the warning is because you've tried to do arithmetic on a void* pointer. when you do arithmetic on pointers, the compiler takes into account the type of the pointer. so a+1 where was an int pointer would add on 4 bytes, a+1 where a was a short pointer would add on two bytes. this is why the compiler complains when you do arithmetic with a void pointer, how many bytes does it add on?

I think if you cast the void*s to char* before doing the addition, it will get rid of the warning.

also, if you're allowed use the standard library, there's a function memcmp.

Tillotson

Works perfectly, makes sense too.

Personal project, I just don't know the libraries yet.