The literal 0 in a pointer context will be converted to a NULL pointer, which can be a non-zero bit pattern (there are some systems where the actual NULL pointe

The literal 0 in a pointer context will be converted to a NULL pointer, which can be a non-zero bit pattern (there are some systems where the actual NULL pointer isn't all zeros). Going through a variable might not do what you think. So this: char *p = 0; is fine, but intptr_t a = 0; char *p = (char *)a; might not do what you expect (set p to the NULL pointer).