unordered_set emplace_hint() in C++

emplace_hint(): This function is available in the File: unordered_set.h

Syntax:

template<class... _Args> std::unordered_set<int>::iterator std::unordered_set<int>::emplace_hint(std::unordered_set<int>::const_iterator __pos, _Args &&...__args) 

This function attempts to insert an element into the unordered_set.

Parameters: Two parameters are required for this function.

__pos – An iterator that serves as a hint as to where the element should be inserted.

__args – Arguments used to generate the element to be inserted.

Returns: An iterator that points to the element with a key equivalent to the one generated from __args (may or may not be the element itself).

Note: The first parameter is only a hint and can potentially improve the performance of the insertion process. 

File: unordered_set.h

Approach

C++

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

int main()
{
    unordered_set<int> st = {1, 4, 6, 7};

    int val = 5;
    st.emplace_hint(st.begin(), val);

    cout << "All elements are: ";
    for (auto it = st.begin(); it != st.end(); it++)
        cout << *it << " ";

    return 0;
}

Output:

All elements are: 5 1 6 4 7