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

cend

#include <map>

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

Const container

end

#include <map>

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

cend

#include <map>

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

Example

Main.cpp

#include <iomanip>
#include <iostream>
#include <map>
#include <string_view>
 
int main() 
{
    const std::map<int, std::string_view> coins {
        {10, "dime"},
        {100, "dollar"},
        {50, "half dollar"},
        {5, "nickel"},
        {1, "penny"},
        {25, "quarter"}
        }; // initializer entries in name alphabetical order
    std::cout << "US coins in circulation, largest to smallest denomination:\n";
    for (auto it = coins.crbegin(); it != coins.crend(); ++it) {
        std::cout << std::setw(11) << it->second << " = ¢" << it->first << '\n';
    }
}

Output

US coins in circulation, largest to smallest denomination:
     dollar = ¢100
half dollar = ¢50
    quarter = ¢25
       dime = ¢10
     nickel = ¢5
      penny = ¢1