Why does calloc exist?

buf = calloc(huge, huge); if (errno) perror("calloc failed"); printf("calloc(huge, huge) returned: %p\n", buf); free(buf); This has a flaw. errno doesn't magically get reset to zero. You should check the return value of calloc, then use errno. Checking if(errno) is not the right way to determine if there was an error.

It may be true today that calloc checks for multiplication overflow and doesn't zero memory if it doesn't need to, that's modern revisionism. Historically, calloc did not do either of those things. eg, from the 4.4 BSD, circa 1993: https://minnie.tuhs.org/cgi-bin/utree.pl?file=4.4BSD/usr/src... void * calloc(num, size) size_t num; register size_t size; { register void *p; size *= num; if (p = malloc(size)) bzero(p, size); return(p); }