Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/ape/lib/ap/gen/toupper.c
#include <ctype.h> toupper(int c) { if(c < 'a' || c > 'z') return c; return (c-'a'+'A'); } tolower(int c) { if(c < 'A' || c > 'Z') return c; return (c-'A'+'a'); }
