std::set end() method

od C++11

// Non const version
iterator end() noexcept;

// Const version
iterator end() const noexcept;

// Const version
const_iterator cend() const noexcept;

do C++11

// Non const version
iterator end();

// Const version
const_iterator cend();

Returns an iterator

to the element past-the-end of the array. If the set is empty, the returned iterator will be equal to begin().

Attempting to dereference a past-the-end iterator is undefined behaviour

.

Parameters

(none)

Return value

Iterator to the first element.

Exceptions

(none)

Complexity

Constant - O(1).

Difference between end and cend

For a const container c, end and cend are the same - c.end() == c.cend()

For non-const container of type c they return different iterators:

Non const container

begin

#include <set>

int main()
{
    std::set<int> set = {1, 2, 3, 4, 5};
    auto it = set.begin(); // Type: std::set<int>::iterator
    *std::prev(it) = 5; // ✔ Ok
}

cbegin

#include <set>

int main()
{
    std::set<int> set = {1, 2, 3, 4, 5};
    auto it = set.cbegin(); // Type: std::set<int>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

Const container

begin

#include <set>

int main()
{
    const std::set<int> set = {1, 2, 3, 4, 5};
    auto it = set.begin(); // Type: std::set<int>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

cbegin

#include <set>

int main()
{
    const std::set<int> set = {1, 2, 3, 4, 5};
    auto it = set.cbegin(); // Type: std::set<int>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

Example

Main.cpp

#include <algorithm>
#include <iostream>
#include <set>
 
int main() {
  std::set<int> set = { 3, 1, 4, 1, 5, 9, 2, 6, 5 };
  std::for_each(set.cbegin(), set.cend(), [](int x) {
    std::cout << x << ' ';
  });
  std::cout << '\n';
}

Output

1 2 3 4 5 6 9