NAME¶

std::ranges::view_interface::data - std::ranges::view_interface::data

Synopsis¶

constexpr auto data() (1) (since C++20)
requires std::contiguous_iterator<ranges::iterator_t<D>>;
constexpr auto data() const

requires ranges::range<const D> && (2) (since C++20)

std::contiguous_iterator<ranges::iterator_t<const D>>;

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).

Parameters¶

(none)

Return value¶

The address denoted by the beginning iterator.

Notes¶

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

* std::ranges::common_view
* std::ranges::drop_view
* std::ranges::drop_while_view
* std::ranges::ref_view
* std::ranges::subrange
* std::ranges::take_view
* std::ranges::take_while_view

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:

* std::ranges::basic_istream_view
* std::ranges::elements_view
* std::ranges::filter_view
* std::ranges::iota_view
* std::ranges::join_view
* std::ranges::lazy_split_view
* std::ranges::reverse_view
* std::ranges::split_view
* std::ranges::transform_view

Example¶

// Run this code

#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!

See also¶

data obtains the pointer to the underlying array
(C++17) (function template)
ranges::data obtains a pointer to the beginning of a contiguous range
(C++20) (customization point object)
ranges::cdata obtains a pointer to the beginning of a read-only contiguous range
(C++20) (customization point object)
to_address obtains a raw pointer from a pointer-like type
(C++20) (function template)