std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::begin, std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::cbegin
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().
Return value
Iterator to the first element.
Complexity
Constant.
Example
#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
| returns an iterator to the end (public member function) |
|
|
(C++11)(C++14) | returns an iterator to the beginning of a container or array (function template) |
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