unordered_multiset emplace_hint() function in C++ STL

The unordered_multiset::emplace_hint() is a built-in function in C++ STL which inserts a new element in the unordered_multiset container. It starts searching from the position provided in the parameter for the insertion point of the element. The position only acts as a hint, it does not decide the position at which the insertion is to be done. The insertion is done automatically at the position according to the container’s criterion. It increases the size of the container by one.

Syntax:

unordered_multiset_name.emplace_hint(iterator position, val)

Parameters: The function accepts two mandatory parameters which are described below:

  • position: it specifies the iterator pointing to the position from where search operation for insertion is to be started.
  • val: it specifies the element which is to be inserted in the container.

Return Value: It returns an iterator which points to the newly inserted element.

Below programs illustrates the above function:

Program 1:

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program to illustrate the
// unordered_multiset::emplace_hint()
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
  
    // declaration
    unordered_multiset<int> sample;
  
    // inserts element using emplace_hint()
  
    // fast insertions as the search starts
    // from the previously inserted positions
    auto it = sample.emplace_hint(sample.begin(), 11);
    it = sample.emplace_hint(it, 11);
    it = sample.emplace_hint(it, 11);
  
    // slow insertions as the search starts from the
    // beginning of the containers
    sample.emplace_hint(sample.begin(), 12);
    sample.emplace_hint(sample.begin(), 13);
    sample.emplace_hint(sample.begin(), 13);
    sample.emplace_hint(sample.begin(), 14);
  
    cout << "Elements: ";
  
    for (auto it = sample.begin(); it != sample.end(); it++)
        cout << *it << " ";
    return 0;
}

chevron_right


Output:

Elements: 14 11 11 11 12 13 13

Program 2:

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program to illustrate the
// unordered_multiset::emplace_hint() function
#include <bits/stdc++.h>
using namespace std;
  
int main()
{
  
    // declaration
    unordered_multiset<char> sample;
  
    // inserts element using emplace_hint()
  
    // fast insertions as the search starts
    // from the previously inserted positions
    auto it = sample.emplace_hint(sample.begin(), 'a');
    it = sample.emplace_hint(it, 'a');
    it = sample.emplace_hint(it, 'a');
    it = sample.emplace_hint(it, 'b');
  
    // slow insertions as the search starts from the
    // beginning of the containers
    sample.emplace('b');
    sample.emplace('c');
    sample.emplace('d');
  
    cout << "Elements: ";
  
    for (auto it = sample.begin(); it != sample.end(); it++)
        cout << *it << " ";
    return 0;
}

chevron_right


Output:

Elements: d a a a b b c


My Personal Notes arrow_drop_up

The function of education is to teach one to think intensively and to think critically

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.




Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.