/* strncmp - compare at most n characters of string s1 to s2 */ #include <string.h> int strncmp(s1, s2, n) /* <0 for <, 0 for ==, >0 for > */ _CONST char *s1; _CONST char *s2; size_t n; { register _CONST char *scan1; register _CONST char *scan2; register size_t count; scan1 = s1; scan2 = s2; count = n + 1; /* extra so predecrement tests remainder */ while (--count > 0 && *scan1 != '\0' && *scan1 == *scan2) { scan1++; scan2++; } if (count <= 0) return(0); /* The following case analysis is necessary so that characters which * look negative collate low against normal characters but high * against the end-of-string NUL. */ if (*scan1 == '\0' && *scan2 == '\0') return(0); else if (*scan1 == '\0') return(-1); else if (*scan2 == '\0') return(1); else return(*scan1 - *scan2); }