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std::ranges...face::front(3)   C++ Standard Libary  std::ranges...face::front(3)

NAME
     std::ranges::view_interface::front - std::ranges::view_interface::front

Synopsis
	constexpr decltype(auto) front()	     (1) (since C++20)
	    requires ranges::forward_range<D>;
	constexpr decltype(auto) front() const	     (2) (since C++20)
	    requires ranges::forward_range<const D>;

	The  default implementation of front() member function returns the first
     element in
	the view of the derived type. Whether the element is returned  by  value
     or by
	reference depends on the operator* of the iterator type.

	1) Let derived be static_cast<D&>(*this). Equivalent to return
	*ranges::begin(derived);.  The	behavior is undefined if empty() is true
     (i.e. the
	beginning iterator compares equal to the sentinel), even if the iterator
     obtained in
	the same way is dereferenceable.
	2) Same as (1), except that derived is static_cast<const D&>(*this).

Parameters
	(none)

Return value
	The first element in the view.

Notes
	In C++20, no type derived from std::ranges::view_interface in the  stan-
     dard library
	provides  their  own  front() member function. Almost all of these types
     use the
	default implementation.

	A notable exception is	std::ranges::basic_istream_view.  For  it  never
     satisfies
	forward_range, the view cannot use the inherited front().

	The    inherited    front()    member	 function   is	 available   for
     std::ranges::empty_view, but
	a call to it always results in undefined behavior.

Example
	 This section is incomplete
	 Reason: no example

See also
	begin
	cbegin	       returns an iterator to the beginning of	a  container  or
     array
	(C++11)        (function template)
	(C++14)
	ranges::begin  returns an iterator to the beginning of a range
	(C++20)        (customization point object)
	ranges::cbegin returns an iterator to the beginning of a read-only range
	(C++20)        (customization point object)

Category:
	  * Todo no example

http://cppreference.com 	   2024.06.10	    std::ranges...face::front(3)
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