NAME

std::vector::begin,std::vector::cbegin - std::vector::begin,std::vector::cbegin

Synopsis

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

Parameters

(none)

Return value

Iterator to the first element.

Complexity

Constant.

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.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.