ref: 97bfd21a430fbac3267e12e5d67a92a7f5ced8a9 dir: /lib/c/src/isalnum.c/
#define __USE_MACROS #include <ctype.h> #undef isalnum int isalnum(int c) { return (__ctype+1)[c] & (_U|_L|_D); }