[字符串处理] strrev的实现

/*
   Reverses the order of characters in the string.
   The terminating null character remains in place.
   把字符串的所有字符的顺序颠倒过来（不包括空字符NULL）。
   返回指向颠倒顺序后的字符串指针。
*/

char * my_strrev(char *str)
{
   char *right = str;
   char *left = str;
   char ch;
   while (*right) right++;
   right--;
   while (left < right)
   {
       ch = *left;
        *left++ = *right;
        *right-- = ch;
   }
   return(str);
}