ref: 2e89286f4ee1ef53e3acb6e4ef4b43909e9fc9e8 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); }