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eb4a14ed LC |
1 | /* strncasecmp.c -- case insensitive string comparator |
2 | Copyright (C) 1998-1999, 2005-2007, 2009-2012 Free Software Foundation, Inc. | |
3 | ||
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU Lesser General Public License as published by | |
6 | the Free Software Foundation; either version 2, or (at your option) | |
7 | any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU Lesser General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Lesser General Public License | |
15 | along with this program; if not, write to the Free Software Foundation, | |
16 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ | |
17 | ||
18 | #include <config.h> | |
19 | ||
20 | /* Specification. */ | |
21 | #include <string.h> | |
22 | ||
23 | #include <ctype.h> | |
24 | #include <limits.h> | |
25 | ||
26 | #define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch)) | |
27 | ||
28 | /* Compare no more than N bytes of strings S1 and S2, ignoring case, | |
29 | returning less than, equal to or greater than zero if S1 is | |
30 | lexicographically less than, equal to or greater than S2. | |
31 | Note: This function cannot work correctly in multibyte locales. */ | |
32 | ||
33 | int | |
34 | strncasecmp (const char *s1, const char *s2, size_t n) | |
35 | { | |
36 | register const unsigned char *p1 = (const unsigned char *) s1; | |
37 | register const unsigned char *p2 = (const unsigned char *) s2; | |
38 | unsigned char c1, c2; | |
39 | ||
40 | if (p1 == p2 || n == 0) | |
41 | return 0; | |
42 | ||
43 | do | |
44 | { | |
45 | c1 = TOLOWER (*p1); | |
46 | c2 = TOLOWER (*p2); | |
47 | ||
48 | if (--n == 0 || c1 == '\0') | |
49 | break; | |
50 | ||
51 | ++p1; | |
52 | ++p2; | |
53 | } | |
54 | while (c1 == c2); | |
55 | ||
56 | if (UCHAR_MAX <= INT_MAX) | |
57 | return c1 - c2; | |
58 | else | |
59 | /* On machines where 'char' and 'int' are types of the same size, the | |
60 | difference of two 'unsigned char' values - including the sign bit - | |
61 | doesn't fit in an 'int'. */ | |
62 | return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0); | |
63 | } |