std::multimap 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 array 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

end

#include <map>

int main()
{
    std::multimap<int, float> map = { {1, 1.f}, {2, 3.f}, {5, 8.f} };
    auto it = arr.end(); // Type: std::multimap<int, float>::iterator
    *std::prev(it) = 5; // ✔ Ok
}

cend

#include <map>

int main()
{
    std::multimap<int, float> map = { {1, 1.f}, {2, 3.f}, {5, 8.f} };
    auto it = arr.cend(); // Type: std::multimap<int, float>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

Const container

end

#include <map>

int main()
{
    const std::multimap<int, float> map = { {1, 1.f}, {2, 3.f}, {5, 8.f} };
    auto it = arr.end(); // Type: std::multimap<int, float>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

cend

#include <map>

int main()
{
    const std::multimap<int, float> map = { {1, 1.f}, {2, 3.f}, {5, 8.f} };
    auto it = arr.cend(); // Type: std::multimap<int, float>::const_iterator
    *std::prev(it) = 5; // ❌ Error! 
}

Example

Main.cpp

#include <algorithm>
#include <cassert>
#include <iostream>
#include <map>
#include <string>
#include <cstddef>
 
int main()
{
    auto show_node = [](const auto& node, char ending = '\n') {
        std::cout << "{ " << node.first << ", " << node.second << " }" << ending;
    };
 
    std::multimap<std::size_t, std::string> mmap;
    assert(mmap.begin() == mmap.end());   // OK
    assert(mmap.cbegin() == mmap.cend()); // OK
 
    mmap.insert({ sizeof(long), "LONG" });
    show_node(*(mmap.cbegin()));
    assert(mmap.begin() != mmap.end());   // OK
    assert(mmap.cbegin() != mmap.cend()); // OK
    mmap.begin()->second = "long";
    show_node(*(mmap.cbegin()));
 
    mmap.insert({ sizeof(int), "int" });
    show_node(*mmap.cbegin());
 
    mmap.insert({ sizeof(short), "short" });
    show_node(*mmap.cbegin());
 
    mmap.insert({ sizeof(char), "char" });
    show_node(*mmap.cbegin());
 
    mmap.insert({{ sizeof(float), "float" }, { sizeof(double), "double" }});
 
    std::cout << "mmap = { ";
    std::for_each(mmap.cbegin(), mmap.cend(), [&](const auto& n) { show_node(n, ' '); });
    std::cout << "};\n";
}

Output

{ 8, LONG }
{ 8, long }
{ 4, int }
{ 2, short }
{ 1, char }
mmap = { { 1, char } { 2, short } { 4, int } { 4, float } { 8, long } { 8, double } };