string rotation

Well, given a char * and an integer to rotate it clockwise or counter clockwise, lets c how to rotate it.

Ok. the basic idea to rotate a string counter clockwise is
1 : reverse first n - 1 characters.
2 : reverse the rest of the characters.
3 : reverse the whole string.


Eg:
Consider "hello" and you wanted to rotate it thrice in the counter clockwise direction.
So, here are the stages:
After 1 : "ehllo"
After 2 : "eholl"
After 3 : "llohe"
which is the final answer.

try it out for clockwise rotation before looking at the snippet below. It's fun.

enum
{
 SUCCESS,
 FAILURE
};


int
reverse(char *in, unsigned int start_index, 
unsigned int end_index)
{
 char temp;
 if (in == NULL || start_index > end_index)
  return (FAILURE);
 while (start_index < end_index) {
  temp = in[start_index];
  in[start_index] = in[end_index];
  in[end_index] = temp;
  start_index++;
  end_index--;
 }
 return (SUCCESS);
}


int
rotate_string(char *rotate_me, unsigned int times, 
unsigned int is_clockwise)
{
 unsigned int len = 0;

 if (rotate_me == NULL)
  return (FAILURE);
 //initialize the length;
 len = strlen(rotate_me);
 //if times > len, fix it.
 times %= len;
 //fix if rotation needs to be clockwise
 if (times != 0 && is_clockwise) {
  times = len - times;
 }
 /*
  * First, reverse the times - 1 characters.
  * Now, reverse times to len - 1
  * Finally, reverse the whole string.
  */
 if (times > 0 &&
  (
   reverse(rotate_me, 0, times - 1) == FAILURE ||
   reverse(rotate_me, times, len - 1) == FAILURE ||
   reverse(rotate_me, 0, len - 1) == FAILURE
  )
 ) {
  return (FAILURE);
 }

 return (SUCCESS);
}

and that's the way it's done :)