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std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::rbegin, std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::crbegin - cppreference.com

From cppreference.com

reverse_iterator rbegin() noexcept;

 (1) (since C++23)

const_reverse_iterator rbegin() const noexcept;

 (2) (since C++23)

const_reverse_iterator crbegin() const noexcept;

 (3) (since C++23)

Returns a reverse iterator to the first element of the reversed flat_map. It corresponds to the last element of the non-reversed flat_map. If the flat_map is empty, the returned iterator is equal to rend().

Return value

Reverse iterator to the first element.

Complexity

Constant.

Notes

The underlying iterator of the returned reverse iterator is the end iterator. Hence the returned iterator is invalidated if and when the end iterator is invalidated.

Example

#include <iomanip>
#include <iostream>
#include <string_view>
#include <flat_map>

int main()
{
    const std::flat_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

See also

returns a reverse iterator to the end
(public member function) [edit]
returns a reverse iterator to the beginning of a container or array
(function template) [edit]