NAME

std::array::data - std::array::data

Synopsis

T* data() noexcept; (since C++11)
(until C++17)
constexpr T* data() noexcept; (since C++17)
const T* data() const noexcept; (since C++11)
(until C++17)
constexpr const T* data() const noexcept; (since C++17)

Returns pointer to the underlying array serving as element storage. The pointer is
such that range [data(); data() + size()) is always a valid range, even if the
container is empty (data() is not dereferenceable in that case).

Parameters

(none)

Return value

Pointer to the underlying element storage. For non-empty containers, the returned
pointer compares equal to the address of the first element.

Complexity

Constant.

Notes

If size() is 0, data() may or may not return a null pointer.

Example

// Run this code

#include <cstddef>
#include <iostream>
#include <span>
#include <array>

void pointer_func(const int* p, std::size_t size)
{
std::cout << "data = ";
for (std::size_t i = 0; i < size; ++i)
std::cout << p[i] << ' ';
std::cout << '\n';
}

void span_func(std::span<const int> data) // since C++20
{
std::cout << "data = ";
for (const int e : data)
std::cout << e << ' ';
std::cout << '\n';
}

int main()
{
std::array<int, 4> container { 1, 2, 3, 4 };

// Prefer container.data() over &container[0]
pointer_func(container.data(), container.size());

// std::span (C++20) is a safer alternative to separated pointer/size.
span_func({container.data(), container.size()});
}

Output:

data = 1 2 3 4
data = 1 2 3 4