删除字符串中的子串(20)

#include<stdio.h>
#include<string.h>
int issubstring(char *s1,char *s2)
{
int i=0,j;
int len2=strlen(s2);
while(s1[i+len2-1]!='\0')
{
for(j=0;s2[j]!='\0';j++)
if(s1[i+j]!=s2[j]) break;
if(s2[j]=='\0') return i;
i++;
}
return -1;
}
int main()
{
char s1[81],s2[81];
int i,k,len;
while(gets(s1)!=NULL)
{
gets(s2);
len=strlen(s2);
while(issubstring(s1,s2)>=0)
{
k=issubstring(s1,s2);
do{
s1[k]=s1[k+len];
k++;
}while(s1[k+len-1]!='\0');
}
puts(s1);
}
return 0;
}