unordered_multimap begin() and end() function in C++ STL

Last Updated : 17 Jun, 2022

The unordered_multimap::begin() is a built-in function in C++ STL that returns an iterator pointing to the first element in the container or to the first element in one of its buckets.

Syntax:

unordered_multimap_name.begin(n)

Parameters: The function accepts one parameter. If a parameter is passed, it returns an iterator pointing to the first element in the bucket. If no parameter is passed, then it returns a constant iterator pointing to the first element in the unordered_multimap container.

Return Value: It returns an iterator. It cannot be used to change the value of the unordered_multimap element.

Below are programs that illustrate the above function:

Program 1:

CPP

// C++ program to illustrate the
// unordered_multimap::begin() function

#include& lt; bits / stdc++.h & gt;
using namespace std;

int main()
{

    // declaration
    unordered_multimap& lt;
    int, int& gt;
    sample;

    // inserts element
    sample.insert({ 1, 2 });
    sample.insert({ 3, 4 });
    sample.insert({ 3, 4 });
    sample.insert({ 2, 3 });
    sample.insert({ 2, 3 });

    // prints all element
    cout& lt;
    <
    "
    Key and Elements : \n& quot;
    ;
    for (auto it = sample.