1 #include<stdio.h>
 2 #include<stdlib.h>
 3 #include<string.h>
 4 char * htmlSource="abc<p class=‘c1‘>defg</p>hijk<p style=‘width=100px;‘>lmn</p>";
 5 char * GetSubString(char* Source,int length)
 6 {
 7     int htmlLength=0;
 8     for(int i=0;i<strlen(Source);i++)
 9     {
10         if(Source[i]==‘<‘)
11         {
12             while(Source[i]!=‘>‘)
13                 i++;
14         }
15         else
16             htmlLength++;
17     }
18     if(length>htmlLength)
19     {
20         printf("截取长度过长\n");
21         return NULL;
22     }
23     else
24     {
25         char* target=(char *)malloc(sizeof(char)*(strlen(Source)+1));
26         int sum1=0;
27         int sum2=0;   
28         int flag=0;
29         for(int i=0;i<length;i++)
30         {
31             if(Source[sum2]==‘<‘)
32             {
33                 if(Source[sum2+1]==‘p‘)
34                     flag=1;
35                 else if(Source[sum2+1]==‘/‘)
36                     flag=0;
37                 do
38                 {
39                     target[sum1++]=Source[sum2++];
40                 }
41                 while(Source[sum2]!=‘>‘);
42                 target[sum1++]=Source[sum2++];
43                 target[sum1++]=Source[sum2++];
44             }
45             else
46             {
47                 target[sum1++]=Source[sum2++];
48             }
49         }
50         if(flag==1)
51         {
52             target[sum1++]=‘<‘;
53             target[sum1++]=‘/‘;
54             target[sum1++]=‘p‘;
55             target[sum1++]=‘>‘;
56             flag=0;
57         }
58         target[sum1]=‘\0‘;
59         return target;
60     }
61 }
62 void main()
63 {
64     int length=0;
65     while(length!=-1)
66     {
67         printf("输入截取长度\n");
68         scanf("%d",&length);
69         char * target=GetSubString(htmlSource,length);
70         printf("%s\n",target);
71         free(target);
72     }
73 }