std::deque<T,Allocator>::begin, std::deque<T,Allocator>::cbegin

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std::deque

Member types
Member functions
deque::deque deque::~deque deque::operator= deque::assign deque::assign_range (C++23)   deque::get_allocator Element access deque::at deque::operator[] deque::front deque::back Iterators deque::begindeque::cbegin (C++11) deque::enddeque::cend (C++11) deque::rbegindeque::crbegin (C++11) deque::renddeque::crend (C++11)	Capacity deque::empty deque::size deque::max_size deque::shrink_to_fit (DR*) Modifiers deque::clear deque::insert deque::insert_range (C++23) deque::emplace deque::erase deque::push_front deque::emplace_front (C++11) deque::prepend_range (C++23) deque::pop_front deque::push_back deque::emplace_back (C++11) deque::append_range (C++23) deque::pop_back deque::resize deque::swap
Non-member functions
operator==operator<=> (C++20) swap(std::deque) erase(std::deque)erase_if(std::deque) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)

 

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().

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

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