Adobe Question: Implement Binary Search using one comparison per iteration.

Solution: 

// Search value in array a of length size
int binarySearch( int* a, int value, int low, int high, int size) 
{
    while (low < high)
    {
        int mid = low + ((high - low) / 2); // Avoid overflow (low + high)
           if (a[mid] < value)
               low = mid + 1;
           else
                //can't be high = mid-1: as a[mid] >= value,
                //so high can't be < mid as a[mid] can be = value
                high = mid;
    }
       // high == low
       if ((low < size) && (a[low] = = value))
           return low; // found
       else
           return -1; // not found
}