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

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C++
Containers library
std::vector
Member types
Member functions
Non-member functions
(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)
(constexpr since C++20)
const_iterator begin ( ) const ;
(2) (noexcept since C++11)
(constexpr since C++20)
const_iterator cbegin ( ) const noexcept ;
(3) (since C++11)
(constexpr 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.

Notes

libc++ backports cbegin() 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.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.

See also

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