Figure 4.2.1: Binary search algorithm.
#include <iostream>
using namespace std;
int BinarySearch(int numbers[], int numbersSize, int key) {
int mid;
int low;
int high;
low = 0;
high = numbersSize - 1;
while (high >= low) {
mid = (high + low) / 2;
if (numbers[mid] < key) {
low = mid + 1;
}
else if (numbers[mid] > key) {
high = mid - 1;
}
else {
return mid;
}
}
return -1; // not found
}
int main() {
int numbers[] = {2, 4, 7, 10, 11, 32, 45, 87};
const int NUMBERS_SIZE = 8;
int i;
int key;
int keyIndex;
cout << "NUMBERS: ";
for (i = 0; i < NUMBERS_SIZE; ++i) {
cout << numbers[i] << " ";
}
cout << endl;
cout << "Enter a value: ";
cin >> key;
keyIndex = BinarySearch(numbers, NUMBERS_SIZE, key);
if (keyIndex == -1) {
cout << key << " was not found." << endl;
}
else {
cout << "Found " << key << " at index " << keyIndex << " ." << endl;
}
return 0;
}
