binary_search.cpp

#include <iostream>
using namespace std;

int binary_search(int data[], int size, int key) {
    int left = 0, right = size - 1, mid = (left + right) / 2;
    while (left <= right) {  // Caution: '<=' instead of '<'!
        if (key > data[mid]) {
            left = mid + 1;
            mid = (left + right) / 2;
        } else if (key < data[mid]) {
            right = mid - 1;
            mid = (left + right) / 2;
        } else {
            return mid;
        }
    }

    return -1;
}
int main() {
    int data[] = {2, 5, 8, 13, 52, 79, 159, 500, 687, 861, 901, 999, 1000};
    cout << binary_search(data, 12, 5) << endl;

    return 0;
}