1 /*
2 FUNCTION
3 <<strncasecmp>>---case-insensitive character string compare
4
5 INDEX
6 strncasecmp
7
8 SYNOPSIS
9 #include <strings.h>
10 int strncasecmp(const char *<[a]>, const char * <[b]>, size_t <[length]>);
11
12 DESCRIPTION
13 <<strncasecmp>> compares up to <[length]> characters
14 from the string at <[a]> to the string at <[b]> in a
15 case-insensitive manner.
16
17 RETURNS
18
19 If <<*<[a]>>> sorts lexicographically after <<*<[b]>>> (after
20 both are converted to lowercase), <<strncasecmp>> returns a
21 number greater than zero. If the two strings are equivalent,
22 <<strncasecmp>> returns zero. If <<*<[a]>>> sorts
23 lexicographically before <<*<[b]>>>, <<strncasecmp>> returns a
24 number less than zero.
25
26 PORTABILITY
27 <<strncasecmp>> is in the Berkeley Software Distribution.
28
29 <<strncasecmp>> requires no supporting OS subroutines. It uses
30 tolower() from elsewhere in this library.
31
32 QUICKREF
33 strncasecmp
34 */
35
36 #include <strings.h>
37 #include <ctype.h>
38
39 int
strncasecmp(const char * s1,const char * s2,size_t n)40 strncasecmp (const char *s1,
41 const char *s2,
42 size_t n)
43 {
44 int d = 0;
45 for ( ; n != 0; n--)
46 {
47 const int c1 = tolower(*s1++);
48 const int c2 = tolower(*s2++);
49 if (((d = c1 - c2) != 0) || (c2 == '\0'))
50 break;
51 }
52 return d;
53 }
54