ref: 0bea8c5077c0ed1f2c61ce65f0b8f14eed89eca3 dir: /lib/c/isalnum.c/
#define __USE_MACROS #include <ctype.h> #undef isalnum int isalnum(int c) { return (__ctype+1)[c] & (_U|_L|_D); }