std::{{{1}}}::data

 

C++

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Symbols index

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T* data();
const T* data() const;

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 <{{{1}}}>
 
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::{{{1}}}<int> 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

See also

front	access the first element (public member function of std::{{{1}}})
back	access the last element (public member function of std::{{{1}}})
size	returns the number of elements (public member function of std::{{{1}}})
span (C++20)	a non-owning view over a contiguous sequence of objects (class template)
data (C++17)	obtains the pointer to the underlying array (function template)