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关于strcmp函数

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发表于 2018-5-22 11:59:24 | 显示全部楼层 |阅读模式

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本帖最后由 御笔剑客 于 2018-5-22 14:28 编辑

如果比较两个长度不等的字符,最后的返回值是什么决定的?
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发表于 2018-5-22 12:58:28 | 显示全部楼层
这个答案是否满意

  1. /* Copyright (C) 1991-2017 Free Software Foundation, Inc.
  2.    This file is part of the GNU C Library.

  3.    The GNU C Library is free software; you can redistribute it and/or
  4.    modify it under the terms of the GNU Lesser General Public
  5.    License as published by the Free Software Foundation; either
  6.    version 2.1 of the License, or (at your option) any later version.

  7.    The GNU C Library is distributed in the hope that it will be useful,
  8.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  9.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  10.    Lesser General Public License for more details.

  11.    You should have received a copy of the GNU Lesser General Public
  12.    License along with the GNU C Library; if not, see
  13.    <http://www.gnu.org/licenses/>.  */

  14. #include <string.h>

  15. #undef strcmp

  16. #ifndef STRCMP
  17. # define STRCMP strcmp
  18. #endif

  19. /* Compare S1 and S2, returning less than, equal to or
  20.    greater than zero if S1 is lexicographically less than,
  21.    equal to or greater than S2.  */
  22. int
  23. STRCMP (const char *p1, const char *p2)
  24. {
  25.   const unsigned char *s1 = (const unsigned char *) p1;
  26.   const unsigned char *s2 = (const unsigned char *) p2;
  27.   unsigned char c1, c2;

  28.   do
  29.     {
  30.       c1 = (unsigned char) *s1++;
  31.       c2 = (unsigned char) *s2++;
  32.       if (c1 == '\0')
  33.         return c1 - c2;
  34.     }
  35.   while (c1 == c2);

  36.   return c1 - c2;
  37. }
  38. libc_hidden_builtin_def (strcmp)
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