Unfortunately, strdup is not posix compliant. If you want to use it and maintain portability, you'll have to write your own.

Er, you're kidding, right? drand48 isn't in Posix either, for example. Someone who runs on Motif and Mac has strdup as the least of their worries. But just in case it's stopping anyone: char *strdup(const char *x) { char *p; return (p = malloc(strlen(x) + 1)) ? strcpy(p, x) : 0; } (Deliberately written too-cleverly. Lame compilers will need to cast to 0)