/* * strncasecmp.c */ #include #include int strncasecmp(const char *s1, const char *s2, size_t n) { const unsigned char *c1 = s1, *c2 = s2; unsigned char ch; int d = 0; while ( n-- ) { /* toupper() expects an unsigned char (implicitly cast to int) as input, and returns an int, which is exactly what we want. */ d = toupper(ch = *c1++) - toupper(*c2++); if ( d || !ch ) break; } return d; }