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Showing content from https://en.cppreference.com/w/cpp/language/../error/error_code/../../../cpp/iterator/data.html below:

std::data - cppreference.com

template< class C > constexpr auto data( C& c ) -> decltype(c.data());

(1) (since C++17)

template< class C > constexpr auto data( const C& c ) -> 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) (4) (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.

4) Returns il.begin().

[edit] Parameters c - a container or view with a data() member function array - an array of arbitrary type il - an std::initializer_list [edit] Return value

1,2) c.data()

3) array

4) il.begin()

[edit] Exceptions

1) May throw implementation-defined exceptions.

[edit] Notes

The overload for std::initializer_list is necessary because it does not have a member function data.

[edit] Possible implementation First version

template<class C>
constexpr auto data(C& c) -> decltype(c.data())
{
    return c.data();
}

Second version

template<class C>
constexpr auto data(const C& c) -> decltype(c.data())
{
    return c.data();
}

Third version

template<class T, std::size_t N>
constexpr T* data(T (&array)[N]) noexcept
{
    return array;
}

Fourth version

template<class E>
constexpr const E* data(std::initializer_list<E> il) noexcept
{
    return il.begin();
}

[edit] 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:

[edit] 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]

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