NAME

std::array::begin,std::array::cbegin - std::array::begin,std::array::cbegin

Synopsis

iterator begin() noexcept; (until C++17)
constexpr iterator begin() noexcept; (since C++17)
const_iterator begin() const noexcept; (until C++17)
constexpr const_iterator begin() const noexcept; (since C++17)
const_iterator cbegin() const noexcept; (until C++17)
constexpr const_iterator cbegin() const noexcept; (since C++17)

Returns an iterator to the first element of the array.

If the array 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 <array>
#include <iostream>
#include <algorithm>
#include <iomanip>

int main()
{
std::cout << std::boolalpha;

std::array<int, 0> empty;
std::cout << "1) "
<< (empty.begin() == empty.end()) << ' ' // true
<< (empty.cbegin() == empty.cend()) << '\n'; // true
// *(empty.begin()) = 42; // => undefined behaviour at run-time

std::array<int, 4> numbers{5, 2, 3, 4};
std::cout << "2) "
<< (numbers.begin() == numbers.end()) << ' ' // false
<< (numbers.cbegin() == numbers.cend()) << '\n' // false
<< "3) "
<< *(numbers.begin()) << ' ' // 5
<< *(numbers.cbegin()) << '\n'; // 5

*numbers.begin() = 1;
std::cout << "4) " << *(numbers.begin()) << '\n'; // 1
// *(numbers.cbegin()) = 42; // compile-time error:
// read-only variable is not assignable

// print out all elements
std::cout << "5) ";
std::for_each(numbers.cbegin(), numbers.cend(), [](int x) {
std::cout << x << ' ';
});
std::cout << '\n';

constexpr std::array constants{'A', 'B', 'C'};
static_assert(constants.begin() != constants.end()); // OK
static_assert(constants.cbegin() != constants.cend()); // OK
static_assert(*constants.begin() == 'A'); // OK
static_assert(*constants.cbegin() == 'A'); // OK
// *constants.begin() = 'Z'; // compile-time error:
// read-only variable is not assignable
}

Output:

1) true true
2) false false
3) 5 5
4) 1
5) 1 2 3 4