C++ STL Binary Search

1. C++ STL binary_search() Overview
2. C++ Program for Binary Search

C++ provides us with a ready-to-use function binary_search() so that we don’t have to implement the function ourselves. It is a very simple to use and efficiently implemented method and not prone to errors.

C++ STL binary_search() Overview

Syntax

DEFAULT
    : template <class ForwardIterator, class T>
      bool
      binary_search(ForwardIterator first, ForwardIterator last, const T& val);

CUSTOM COMPARISON FUNCTION
    : template <class ForwardIterator, class T, class Compare>
      bool
      binary_search(ForwardIterator first, ForwardIterator last, const T& val,
                    Compare comp);

Here, T can be any of the following: int, float, short, long, byte, char, double, and even a user-defined Object as well.

It checks whether an element inside [first, last) matches the target element X using the binary search algorithm. By default, it uses the less-than operator to compare elements, but we can also provide our own custom comp as described in the second template given above.

Parameters

Return

If it finds the target element, then it returns true; else it returns false.

C++ Program for Binary Search

#include <bits/stdc++.h>
using namespace std;

int main() {
  vector<int> v = {1, 2, 3, 4, 5, 6};

  if (binary_search(v.begin(), v.end(), 5)) {
    cout << "Element found" << endl;
  } else {
    cout << "Element not found" << endl;
  }

  return 0;
}