关于strcmp函数

御笔剑客

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？

人造人

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. 
   
4.    The GNU C Library is free software; you can redistribute it and/or
   
5.    modify it under the terms of the GNU Lesser General Public
   
6.    License as published by the Free Software Foundation; either
   
7.    version 2.1 of the License, or (at your option) any later version.
   
8. 
   
9.    The GNU C Library 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 GNU
    
12.    Lesser General Public License for more details.
    
13. 
    
14.    You should have received a copy of the GNU Lesser General Public
    
15.    License along with the GNU C Library; if not, see
    
16.    <http://www.gnu.org/licenses/>.  */
    
17. 
    
18. #include <string.h>
    
19. 
    
20. #undef strcmp
    
21. 
    
22. #ifndef STRCMP
    
23. # define STRCMP strcmp
    
24. #endif
    
25. 
    
26. /* Compare S1 and S2, returning less than, equal to or
    
27.    greater than zero if S1 is lexicographically less than,
    
28.    equal to or greater than S2.  */
    
29. int
    
30. STRCMP (const char *p1, const char *p2)
    
31. {
    
32.   const unsigned char *s1 = (const unsigned char *) p1;
    
33.   const unsigned char *s2 = (const unsigned char *) p2;
    
34.   unsigned char c1, c2;
    
35. 
    
36.   do
    
37.     {
    
38.       c1 = (unsigned char) *s1++;
    
39.       c2 = (unsigned char) *s2++;
    
40.       if (c1 == '\0')
    
41.         return c1 - c2;
    
42.     }
    
43.   while (c1 == c2);
    
44. 
    
45.   return c1 - c2;
    
46. }
    
47. libc_hidden_builtin_def (strcmp)
    

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