std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::begin, std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::cbegin
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Tables
std::flat_map
flat_map::beginflat_map::cbegin
iterator begin() noexcept;
(1)
(since C++23) (constexpr since C++26)
const_iterator begin() const noexcept;
(2)
(since C++23) (constexpr since C++26)
const_iterator cbegin() const noexcept;
(3)
(since C++23) (constexpr since C++26)
Returns an iterator to the first element of *this.
If *this is empty, the returned iterator will be equal to end().
Contents
[edit] Return value
Iterator to the first element.
[edit] Complexity
Constant.
[edit] 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
[edit] See also
(C++11)(C++14)
(function template) [edit]