实验11-1-8 查找子串

 1 #include <stdio.h>
 2 #define MAXS 30
 3 
 4 char *search(char *s, char *t);
 5 void ReadString( char s[] ); /* 裁判提供，细节不表 */
 6 
 7 int main()
 8 {
 9     char s[MAXS], t[MAXS], *pos;
10 
11     ReadString(s);
12     ReadString(t);
13     pos = search(s, t);
14     if ( pos != NULL )
15         printf("%d
", pos - s);
16     else
17         printf("-1
");
18 
19     return 0;
20 }
21 
22 /* 你的代码将被嵌在这里 */
23 char *search(char *s, char *t)
24 {
25     
26     int len = 0, i;
27     char *p, *ret;
28     
29     p = t;
30     while (*p != '')
31     {
32         len++;
33         p++;
34     }
35     
36     p = s;
37     while (*p != '')
38     {
39         for (i = 0; i < len; i++)
40         {
41             if (p[i] != t[i])
42             {
43                 break;
44             }
45         }
46         if (i == len)
47         {
48             break;
49         }
50         p++;
51     }
52     if (*p != '')
53     {
54         ret = p;
55     }
56     else
57     {
58         ret = NULL;
59     }
60     
61     return ret;
62 }