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std::ranges::view_interface<D>::data

From cppreference.com
 
 
 
std::ranges::view_interface
Member functions
(C++20)
data
(C++20)
(C++20)
(C++20)
(C++20)
(C++20)
 
constexpr auto data()
    requires std::contiguous_iterator<ranges::iterator_t<D>>;
(1) (since C++20)
constexpr bool data() const
    requires std::contiguous_iterator<ranges::iterator_t<const D>>;
(2) (since C++20)

The default implementation of data() member function obtains the address denoted by the beginning iterator via std::to_address, which is also the lowest address of the contiguous storage (implied by contiguous_iterator) referenced by the view of the derived type when the view is not empty.

1) Let derived be static_cast<D&>(*this). Equivalent to return std::to_address(ranges::begin(derived));.
2) Same as (1), except that derived is static_cast<const D&>(*this).

Contents

[edit] Parameters

(none)

[edit] Return value

The address denoted by the beginning iterator.

[edit] Notes

Following derived types may use the default implementation of data():

Following types are derived from std::ranges::view_interface and do not declare their own data() member function, but they cannot use the default implementation, because their iterator types never satisfy contiguous_iterator:

[edit] Example

#include <array>
#include <iostream>
#include <ranges>
#include <string_view>
 
int main() {
    constexpr std::string_view str { "Hello, C++20!" };
    std::cout << (str | std::views::drop(7)).data() << '\n';
    constexpr static std::array a { 1,2,3,4,5 };
    constexpr auto v { a | std::views::take(3) };
    static_assert( &a[0] == v.data() );
}

Output:

C++20!

[edit] See also

(C++17)
obtains the pointer to the underlying array
(function template) [edit]
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]
obtains a raw pointer from a pointer-like type
(function template) [edit]