// Steve J. Hodges
// CS19: C++ Programming
// binarySearch

#include <iostream>
using namespace std;

// binary search - return pos of key in array
int binarySearch(int [], const int, int);


main(){
  const int ASIZE=17;
  int a[]={1,2,3,4,5,6,7,8,9,10,23,34,45,56,67,78,89};
  int key;
  cout << "Key value to search for?";
  cin >> key;
  cout << binarySearch(a, ASIZE, key);
}

// binary search - return pos of key in array
int binarySearch(int a[], const int AS, int key){
  int lo=0, hi=AS-1, mid;
  while( lo <= hi){
    mid = (lo+hi)/2;
    if (a[mid] == key)
      return mid;
    if (a[mid] > key){
      hi = mid - 1;
    } else {
      lo = mid + 1;
    }
  }
  return -1;
}