63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
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/* Case-insensitive string comparison function.
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Copyright (C) 1998-1999, 2005-2007, 2009-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include <string.h>
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#include <ctype.h>
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#include <limits.h>
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#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
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/* Compare strings S1 and S2, ignoring case, returning less than, equal to or
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greater than zero if S1 is lexicographically less than, equal to or greater
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than S2.
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Note: This function does not work with multibyte strings! */
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int
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strcasecmp (const char *s1, const char *s2)
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{
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const unsigned char *p1 = (const unsigned char *) s1;
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const unsigned char *p2 = (const unsigned char *) s2;
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unsigned char c1, c2;
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if (p1 == p2)
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return 0;
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do
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{
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c1 = TOLOWER (*p1);
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c2 = TOLOWER (*p2);
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if (c1 == '\0')
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break;
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++p1;
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++p2;
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}
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while (c1 == c2);
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if (UCHAR_MAX <= INT_MAX)
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return c1 - c2;
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else
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/* On machines where 'char' and 'int' are types of the same size, the
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difference of two 'unsigned char' values - including the sign bit -
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doesn't fit in an 'int'. */
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return _GL_CMP (c1, c2);
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}
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