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

From cppreference.com
< cpp‎ | container‎ | vector
 
 
Containers library
Sequence
(C++11)
Associative
Unordered associative
Adaptors
Views
(C++20)
 
 
iterator begin();
(until C++11)
iterator begin() noexcept;
(since C++11)
(until C++20)
constexpr iterator begin() noexcept;
(since C++20)
const_iterator begin() const;
(until C++11)
const_iterator begin() const noexcept;
(since C++11)
(until C++20)
constexpr const_iterator begin() const noexcept;
(since C++20)
const_iterator cbegin() const noexcept;
(since C++11)
(until C++20)
constexpr const_iterator cbegin() const noexcept;
(since C++20)

Returns an iterator to the first element of the vector.

If the vector is empty, the returned iterator will be equal to end().

range-begin-end.svg

Contents

[edit] Parameters

(none)

[edit] Return value

Iterator to the first element.

[edit] Complexity

Constant.


[edit] Example

#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.begin(), nums.end(), [](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.begin(), nums.end(), 0) << '\n';
 
    // Prints the first fruit in the vector fruits, checking if there is any.
    if (!fruits.empty())
        std::cout << "First fruit: " << *fruits.begin() << '\n';
 
    if (empty.begin() == empty.end())
        std::cout << "vector 'empty' is indeed empty.\n";
}

Output:

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

[edit] See also

(C++11)
returns an iterator to the end
(public member function) [edit]