Binary search
int BinarySearch(int list[], int size, int key)
{
int left, right, midpt;
left = 0;
right = size - 1;
while (left <= right)
{
midpt = (int) ((left + right) / 2);
if (key == list[midpt])
{
return midpt;
}
else if (key > list[midpt])
left = midpt + 1;
else
right = midpt - 1;
}
return -1;
}