Difference between revisions of "cpp/container/vector/rbegin"
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Revision as of 16:22, 2 November 2012
| reverse_iterator rbegin(); |
(1) | (noexcept since C++11) (constexpr since C++20) |
| const_reverse_iterator rbegin() const; |
(2) | (noexcept since C++11) (constexpr since C++20) |
| const_reverse_iterator crbegin() const noexcept; |
(3) | (since C++11) (constexpr since C++20) |
Returns a reverse iterator to the first element of the reversed vector. It corresponds to the last element of the non-reversed vector. If the vector is empty, the returned iterator is equal to rend().
Contents |
Parameters
(none)
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.
libc++ backports crbegin() to C++98 mode.
Example
Run this code
#include <algorithm> #include <iostream> #include <numeric> #include <string> #include <vector> int main() { std::vector<int> nums{1, 2, 4, 8, 16}; std::vector<std::string> fruits{"orange", "apple", "raspberry"}; std::vector<char> empty; // Print vector. std::for_each(nums.rbegin(), nums.rend(), [](const int n) { std::cout << n << ' '; }); std::cout << '\n'; // Sums all integers in the vector nums (if any), printing only the result. std::cout << "Sum of nums: " << std::accumulate(nums.rbegin(), nums.rend(), 0) << '\n'; // Prints the first fruit in the vector fruits, checking if there is any. if (!fruits.empty()) std::cout << "First fruit: " << *fruits.rbegin() << '\n'; if (empty.rbegin() == empty.rend()) std::cout << "vector 'empty' is indeed empty.\n"; }
Output:
16 8 4 2 1 Sum of nums: 31 First fruit: raspberry vector 'empty' is indeed empty.
See also
| (C++11) |
returns a reverse iterator to the end (public member function) |
| (C++14) |
returns a reverse iterator to the beginning of a container or array (function template) |
