Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/libc/port/toupper.c
#include <ctype.h> int toupper(int c) { if(c < 'a' || c > 'z') return c; return _toupper(c); } int tolower(int c) { if(c < 'A' || c > 'Z') return c; return _tolower(c); }
