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std::array<T,N>::data

From cppreference.com
< cpp‎ | container‎ | array
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).

Contents

[edit] Parameters

(none)

[edit] Return value

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

[edit] Complexity

Constant.

[edit] Notes

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

[edit] Example

#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

[edit] See also

access the first element
(public member function) [edit]
access the last element
(public member function) [edit]
returns the number of elements
(public member function) [edit]
(C++20)
a non-owning view over a contiguous sequence of objects
(class template) [edit]