std::data
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 <hive> | (since C++26) | |
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] |
- 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 forstd::initializer_listwas necessary before P3016R6 because it did not have a member functiondata.
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:
Hello world!
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_list2) std::data was not required to propagate exception specification | 1) removed 2) required |
See also
|
(C++20) | obtains a pointer to the beginning of a contiguous range (customization point object) |
|
(C++20) | obtains a pointer to the beginning of a read-only contiguous range (customization point object) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/cpp/iterator/data
