#include <stdio.h>
#include <string.h>

int main()
{
char a[100]= {0};
int i = 0;
int len = 0;

printf("please input character string:\n");
gets(a);

len = strlen(a);//計算輸入字串的長度；

for(i = 0; i < (len / 2); i++)//只需要判斷前一半（len/2）長度就好了
{
if(a[i] != a[len - 1 - i])//判斷是否為迴文數；
{
printf("不是迴文數\n");
return 0;
}
}

printf("是迴文數\n");

return 0;
}