/**
 * jb-ibs.c
 *   An implementation of binary search by J.B.
 */
 
#include "ibs.h"

int ibs(int *list, const int length, const int value)
{
  int left=0, right = length-1, mid = length/2;

  while (right-left > 1) {
    if (list[mid] < value){
      left = mid;
    }  // end if list[mid]<value
    else {
      right = mid;
    }  // end else list[mid]<value
    mid = (right+left)/2;
    if ( list[mid] == value) {
      return mid;
    } // end if list[mid]==value
  } // end while

/* ****
 If we made it through the while loop, then
        * we have not found the lodation of value;
        * right - left = 1.
 So we check right and left.  
**** */
  if (list[left] == value) {
    return left;
  }  // end if list[left]==value
  if (list[right] == value) {
    return right;
  } // end if list[right]==value

// If it is neither, then value is not in the list so we return -1.  
  return -1;
} // end function ibs