Binary Search Implementation

binary_search_without_iterators.cpp

#include <vector>
#include <iostream>
#include <utility>

template <class T>
auto binarySearch(std::vector<T>& vec, const T& key)
{
    size_t left = 0;
    size_t right = vec.size() + 1;
    size_t middle = (left + right) / 2;
    
    while(left <= right)
    {
        if(vec[middle] == key)
        {
            return std::pair<bool, size_t>(true, middle);
        }
        
        if(vec[middle] < key)
        {
            left = middle - 1;
        }
        else 
        {
            right = middle + 1;
        }
        middle = (left + right) / 2;
    }
    return std::pair<bool, size_t>(false, 0);
}

int main()
{
    std::vector<int> vec {1, 4, 3, 6, 2, -3, 4, -1, 0};
    
    auto exist_pair = binarySearch<decltype(vec)::value_type>(vec, -3);
    if(exist_pair.first)
    {
        std::cout   << "Index: #" << exist_pair.second 
                    << " : Item: " << vec[exist_pair.second] << "\n";
    }
    else 
    {
        std::cout << "Couldn't find Item\n";
    }

    return 0;
}