std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>::begin, std::flat_multimap<Key,T,Compare,KeyContainer,MappedContainer>::cbegin

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Tables

Iterator invalidation

Member function table

Non-member function table

 

std::flat_multimap

Member types

Member functions

flat_multimap::flat_multimap    flat_multimap::operator= Modifiers flat_multimap::clear flat_multimap::erase flat_multimap::swap flat_multimap::extract flat_multimap::replace flat_multimap::insert flat_multimap::insert_range flat_multimap::emplace flat_multimap::emplace_hint Lookup flat_multimap::count flat_multimap::find flat_multimap::contains flat_multimap::equal_range flat_multimap::lower_bound flat_multimap::upper_bound Iterators flat_multimap::beginflat_multimap::cbegin flat_multimap::endflat_multimap::cend flat_multimap::rbeginflat_multimap::crbegin flat_multimap::rendflat_multimap::crend Capacity flat_multimap::size flat_multimap::max_size flat_multimap::empty Observers flat_multimap::key_comp flat_multimap::keys flat_multimap::value_comp flat_multimap::values

Non-member functions

swap(std::flat_multimap) erase_if(std::flat_multimap)     operator==operator<=>

Helper classes

uses_allocator<std::flat_multimap>

Tags

sorted_equivalent          sorted_equivalent_t

Deduction guides

 

iterator begin() noexcept;	(1)	(since C++23)
const_iterator begin() const noexcept;	(2)	(since C++23)
const_iterator cbegin() const noexcept;	(3)	(since C++23)

Returns an iterator to the first element of the flat_multimap.

If the flat_multimap is empty, the returned iterator will be equal to end().

Parameters

(none)

Return value

Iterator to the first element.

Complexity

Constant.

Example

Run this code

#include <iostream>
#include <flat_map>
 
int main()
{
    std::flat_multimap<int, int> map{{4, 13}, {9, 94}, {1, 19}, {4, 42}};
 
    for (auto it = map.cbegin(); it != map.cend(); ++it)
        std::cout << '[' << it->first << "] = " << it->second << '\n';
 
    // Unlike std::multimap's bidirectional iterators, the std::flat_multimap
    // iterators are random-access, so they can be used with the operator[]:
    auto it = map.cbegin();
    assert(it[1] == 19);
    assert(it[4] == 13);
    assert(it[4] == 42);
    assert(it[9] == 94);
}

Output:

[1] = 19
[4] = 13
[4] = 42
[9] = 94

See also

endcend	returns an iterator to the end (public member function)
begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)