◐ Shell
clean mode source ↗

std::data - cppreference.com

From cppreference.com

Defined in header <array>

Defined in header <deque>

Defined in header <flat_map>

(since C++23)

Defined in header <flat_set>

(since C++23)

Defined in header <forward_list>

Defined in header <inplace_vector>

(since C++26)

Defined in header <iterator>

Defined in header <list>

Defined in header <map>

Defined in header <optional>

(since C++26)

Defined in header <regex>

Defined in header <set>

Defined in header <span>

(since C++20)

Defined in header <stacktrace>

(since C++23)

Defined in header <string>

Defined in header <string_view>

Defined in header <unordered_map>

Defined in header <unordered_set>

Defined in header <valarray>

Defined in header <vector> 

template< class C >
constexpr auto data( C& c ) noexcept(noexcept(c.data()))
    -> decltype(c.data());
(1) (since C++17) 
template< class C >
constexpr auto data( const C& c ) noexcept(noexcept(c.data()))
    -> decltype(c.data());
(2) (since C++17) 
template< class T, std::size_t N >
constexpr T* data( T (&array)[N] ) noexcept;
(3) (since C++17)

Returns a pointer to the block of memory containing the elements of the range.

1,2) Returns c.data().

3) Returns array.

Parameters

c - a container or view with a data() member function
array - an array of arbitrary type

Return value

1,2) c.data()

3) array

Exceptions

1,2) What and when the underlying c.data() call throws.

Notes

Feature-test macro Value Std Feature
__cpp_lib_nonmember_container_access 201411L (C++17) std::size(), std::data(), and std::empty()
__cpp_lib_initializer_list 202511L (C++26)
(DR11)		 data and empty member functions of std::initializer_list;
removing unnecessary free functions for std::initializer_list[1]
  1. ↑ As of 2026-05-27, libstdc++ has not treated the addition and removal of functions from P3016R6 as a defect report against C++11, and only applies the changes since C++26.
    The overload for std::initializer_list was necessary before P3016R6 because it did not have a member function data.

Possible implementation

First version 
template<class C>
constexpr auto data(C& c) noexcept(noexcept(c.data()))
    -> decltype(c.data())
{
    return c.data();
}
Second version 
template<class C>
constexpr auto data(const C& c) noexcept(noexcept(c.data()))
    -> decltype(c.data())
{
    return c.data();
}
Third version 
template<class T, std::size_t N>
constexpr T* data(T (&array)[N]) noexcept
{
    return array;
}

Example

#include <cstring>
#include <iostream>
#include <string>

int main()
{
    std::string s{"Hello world!\n"};

    char a[20]; // storage for a C-style string
    std::strcpy(a, std::data(s));
//  [s.data(), s.data() + s.size()] is guaranteed to be an NTBS since C++11

    std::cout << a;
}

Output:

Defect report

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
P3016R6 C++17 1) non-member std::data overload was provided for std::initializer_list
2) std::data was not required to propagate exception specification 		1) removed
2) required

See also

obtains a pointer to the beginning of a contiguous range
(customization point object)[edit]
obtains a pointer to the beginning of a read-only contiguous range
(customization point object)[edit]