unordered_multiset cbegin() function in C++ STL

The unordered_multiset::cbegin() is a built-in function in C++ STL which returns a constant iterator pointing to the first element in the container or to the first element in one of its bucket.

Syntax:

unordered_multiset_name.cbegin(n)

Parameters: The function accepts one parameter. If a parameter is passed, it returns a constant 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_multiset container.

Return Value: It returns a constant iterator. It cannot be used to change the value of the unordered_multiset element.

Below programs illustrates the above function:

Program 1:

// C++ program to illustrate the
// unordered_multiset::cbegin() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration
    unordered_multiset<int> sample;

    // inserts element
    sample.insert(10);
    sample.insert(11);
    sample.insert(15);
    sample.insert(13);
    sample.insert(14);

    // prints all element
    cout << "Elements: ";
    for (auto it = sample.cbegin(); it != sample.cend(); it++)
        cout << *it << " ";

    auto it = sample.cbegin();

    // print the first element
    cout << "\nThe first element: " << *it;

    return 0;
}

Program 2:

// C++ program to illustrate the
// unordered_multiset::cbegin() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration
    unordered_multiset<char> sample;

    // inserts element
    sample.insert('a');
    sample.insert('b');
    sample.insert('c');
    sample.insert('x');
    sample.insert('z');

    // print the first element
    auto it = sample.cbegin();
    cout << "The first element: " << *it;

    it++;
    cout << "\nThe second element: " << *it;

    cout << "\nElements: ";

    // prints all element
    for (auto it = sample.cbegin(); it != sample.cend(); it++)
        cout << *it << " ";
    return 0;
}

Program 3:

// C++ program to illustrate the
// unordered_multiset::cbegin() function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration
    unordered_multiset<char> sample;

    // inserts element
    sample.insert('a');
    sample.insert('b');
    sample.insert('c');
    sample.insert('x');
    sample.insert('z');

    // print the first element
    cout << "The first element in first bucket : " << *sample.cbegin(1);

    cout << "\nElements in first bucket: ";

    // prints all element
    for (auto it = sample.cbegin(1); it != sample.cend(1); it++)
        cout << *it << " ";
    return 0;
}