char * reverse_str(char *s){
    char *p = s;
    char *q = s;
    char temp = 0;

    while(*q != '\0'){
        q++;
    }

    q--;//\0前一个字符

    while(p < q){
        temp = *p;
        *p = *q;
        *q = temp;
        p++;
        q--;
    }

    return s;
}

int main()
{
char s[] = "hello";
 reverse_str(s);
printf("%s", s);
}

olleh