//写一函数int fun(char *p)判断一字符串是否为回文，是返回1，不是返回0，出错返回 - 1 
int fun(char *p)
{if (p == NULL)return -1;else{int length = 0;inti = 0;int judge = 1;length = strlen(p);for (i = 0; i<length / 2; i++){if (p[i] != p[length - 1 - i]){judge = 0;break;}}if (judge == 0)return 0;elsereturn 1;}
}
int fun(char *p)
{int len = strlen(p) - 1;char *q = p + len;if (!p)return -1;while (p < q){if ((*p++) != (*q--))return 0;}return 1;
}