NAME¶

std::flat_map::begin, - std::flat_map::begin,

Synopsis¶

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_map.

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

range-begin-end.svg

Parameters¶

(none)

Return value¶

Iterator to the first element.

Complexity¶

Constant.

Example¶

// Run this code

#include <iostream>
#include <flat_map>

int main()
{
std::flat_map<int, double> map{{4, 4.13}, {9, 9.24}, {1, 1.09}};

for (auto it = map.cbegin(); it != map.cend(); ++it)
std::cout << '[' << it->first << "] = " << it->second << '\n';

// Unlike std::map's bidirectional iterators, the std::flat_map iterators
// are random-access, so they can be used with the operator[]:
auto it = map.cbegin();
assert(it[0] == map[1]);
assert(it[1] == map[4]);
assert(it[2] == map[9]);
}

Output:¶

[1] = 1.09
[4] = 4.13
[9] = 9.24

See also¶

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