unordered_set cend() function in C++ STL

The unordered_set::cend() method is a built-in function in C++ STL which is used to return a const_iterator pointing to past-the-end element in the unordered_set container or in one of it’s bucket. This function does not directly point to any element in the container. It is only used to denote the end of a container or the open end of a range as in [cbegin, cend). 

Note: A const_iterator can only be used to access elements, it cannot modify the elements present in the container. 

Syntax:

unordered_set_name.cend(n);

Parameter: This function accepts a single parameter n. This is an optional parameter and specifies the bucket number. If this parameter is not passed then the cend() method will return a const_iterator pointing to the position just after the last element of the container and if this parameter is passed then the cend() method will return a const_iterator pointing to the position just after the last element in a specific bucket in the unordered_set container. 

Return Value: This function returns a const_iterator pointing to the position just after the last element in the container or a specified bucket in the container. Below programs illustrate the unordered_set::cend() function: 

Program 1: 

CPP

// C++ program to illustrate the
// unordered_set::cend() function

#include <iostream>
#include <unordered_set>

using namespace std;

int main()
{

    unordered_set<int> sampleSet;

    // Inserting elements in the std
    sampleSet.insert(5);
    sampleSet.insert(10);
    sampleSet.insert(15);
    sampleSet.insert(20);
    sampleSet.insert(25);

    // Here, the cend() method is used to
    // iterate in the range of elements
    // present in the unordered_set container
    cout << "Elements present in sampleSet are: \n";
    for (auto itr = sampleSet.cbegin(); itr != sampleSet.cend();
        itr++) {
        cout << *itr << endl;
    }

    return 0;
}

Output:

Elements present in sampleSet are: 
25
5
10
15
20

Program 2: 

CPP

// C++ program to illustrate the
// unordered_set::cend() function

#include <iostream>
#include <unordered_set>

using namespace std;

int main()
{

    unordered_set<string> sampleSet;

    // Inserting elements
    sampleSet.insert("Welcome");
    sampleSet.insert("To");
    sampleSet.insert("GeeksforGeeks");
    sampleSet.insert("Computer Science Portal");
    sampleSet.insert("For Geeks");

    // Here, the cend() method is used to
    // iterate in the range of elements
    // present in the unordered_set container
    cout << "Elements present in sampleSet are: \n";
    for (auto itr = sampleSet.cbegin(); itr != sampleSet.cend();
        itr++) {
        cout << *itr << endl;
    }

    return 0;
}

Output:

Elements present in sampleSet are: 
Welcome
To
GeeksforGeeks
For Geeks
Computer Science Portal

Time complexity: O(1)