NAME¶

std::deque::begin,std::deque::cbegin - std::deque::begin,std::deque::cbegin

Synopsis¶

iterator begin(); (1) (noexcept since C++11)
const_iterator begin() const; (2) (noexcept since C++11)
const_iterator cbegin() const noexcept; (3) (since C++11)

Returns an iterator to the first element of the deque.

If the deque 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.

Notes¶

libc++ backports cbegin() to C++98 mode.

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <deque>

int main()
{
std::deque<int> nums{1, 2, 4, 8, 16};
std::deque<std::string> fruits{"orange", "apple", "raspberry"};
std::deque<char> empty;

// Print deque.
std::for_each(nums.begin(), nums.end(), [](const int n) { std::cout << n << ' '; });
std::cout << '\n';

// Sums all integers in the deque nums (if any), printing only the result.
std::cout << "Sum of nums: "
<< std::accumulate(nums.begin(), nums.end(), 0) << '\n';

// Prints the first fruit in the deque fruits, checking if there is any.
if (!fruits.empty())
std::cout << "First fruit: " << *fruits.begin() << '\n';

if (empty.begin() == empty.end())
std::cout << "deque 'empty' is indeed empty.\n";
}

Output:¶

1 2 4 8 16
Sum of nums: 31
First fruit: orange
deque 'empty' is indeed empty.

See also¶

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