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std::ranges...erface::data(3)  C++ Standard Libary std::ranges...erface::data(3)

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 ad-
     dress 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 imple-
     mentation,
	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 contigu-
     ous range
	(C++20)       (customization point object)
	to_address    obtains a raw pointer from a pointer-like type
	(C++20)       (function template)

http://cppreference.com 	   2024.06.10	   std::ranges...erface::data(3)
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