Binary Search Algorithm

//============================================================================
// Name        : BinarySearch.cpp
// Author      : Danny
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
using namespace std;

int binarySearch(int a[], int left, int right, int k) {
    if (left > right)
        return -1;
    int mid = (left + right) / 2;
    if (a[mid] == k) {
        return mid;
    } else if (a[mid] > k) {
        return binarySearch(a, left, mid - 1, k);
    } else {
        return binarySearch(a, mid + 1, right, k);
    }
}

int main() {
    int a[5] = { 1, 2, 4, 5, 7 };
    int index = binarySearch(a, 0, 4, 7);
    cout << index << endl;
    return 0;
}