C语言程序设计竞赛任务的

获得字符长度，然后两头指针交换

void fun(char *s)
{
      int n = strlen(s);
      for(int i=0;i<n/2;i++)
      {
            char a = s[i];
            s[i] = s[n-i-1];
            s[n-i-1] = a;
      }
}

void fun(char* s)
{
    int i,len;
    char ch;
    len = strlen(s);
    for (i=0;i<len/2;i++)
    {
        ch = s[i];
        s[i] = s[len -i-1];
        s[len - i-1] = ch;
    }
}

供参考：

void fun(char *s)
{
    /*******Program*****/
    int r = strlen(s);
    char i = s[0];
    s[0] = s[r - 1];
    s[r-1] = '\0';
    if (r > 1)         
        fun(s + 1); 
    s[r-1] = i;
    /******* End *****/
}