判断是否为回文串

#include "stdio.h"
#include "string.h"
int main(void)
{
char s[225],*head,*end;
int flag=1,i=0,len=0;
gets(s);
for(;s[i]!='\0';i++)
len+=1;
head=s;
end=s+len-1;
for(;head