// file: binsearch.cpp
// this is the binary search function
// it takes an array, a size, and a key as parameters
// it returns the location of the key if found, returns
// -1 if not found
int binSearch(int ary[], int size, int key)
{
   int found = 0;
   int mid, first, last;

   first = 0; last = size - 1;
   while (first <= last && found == 0)
   {
      mid = (first + last)/2;
      if (key == ary[mid])  // found the location
         found = 1;
      else if (key < ary[mid])  // search the first half
         last = mid - 1;
      else
         first = mid + 1;  // search the second half
   }  // while

   if (found == 0)  // not found
      mid = -1;
   return mid;
}