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std::ranges::min_element(3)    C++ Standard Libary   std::ranges::min_element(3)

NAME
     std::ranges::min_element - std::ranges::min_element

Synopsis
	Defined in header <algorithm>
	Call signature
	template< std::forward_iterator I, std::sentinel_for<I> S, class Proj =
	std::identity,

		  std::indirect_strict_weak_order<std::projected<I,  Proj>> Comp
     (1) (since
	=			      ranges::less			       >
     C++20)
	constexpr I

	    min_element( I first, S last, Comp comp = {}, Proj proj = {} );
	template< ranges::forward_range R, class Proj = std::identity,

		  std::indirect_strict_weak_order<
		      std::projected<ranges::iterator_t<R>,    Proj>>	Comp   =
     (2) (since
	ranges::less							       >
     C++20)
	constexpr ranges::borrowed_iterator_t<R>

	    min_element( R&& r, Comp comp = {}, Proj proj = {} );

	1) Finds the smallest element in the range [first, last).
	2)  Same as (1), but uses r as the source range, as if using ranges::be-
     gin(r) as
	first and ranges::end(r) as last.

	The function-like entities described on this page  are	niebloids,  that
     is:

	  *  Explicit  template  argument lists cannot be specified when calling
     any of them.
	  * None of them are visible to argument-dependent lookup.
	  * When any of them are found by normal unqualified lookup as the  name
     to the left
	    of	the  function-call operator, argument-dependent lookup is inhib-
     ited.

	In practice, they may be implemented as function objects, or  with  spe-
     cial compiler
	extensions.

Parameters
	first, last - iterator-sentinel pair denoting the range to examine
	r	    - the range to examine
	comp	    - comparison to apply to the projected elements
	proj	    - projection to apply to the elements

Return value
	Iterator  to the smallest element in the range [first, last). If several
     elements in
	the range are equivalent to the smallest element, returns  the	iterator
     to the first
	such element. Returns last if the range is empty (i.e., first == last).

Complexity
	Exactly  max(N	-  1,  0) comparisons, where N = ranges::distance(first,
     last).

Possible implementation
     struct min_element_fn {
	 template<std::forward_iterator I, std::sentinel_for<I> S, class Proj  =
     std::identity,
		  std::indirect_strict_weak_order<std::projected<I,  Proj>> Comp
     = ranges::less>
	 constexpr I operator()(I first, S last, Comp comp = {}, Proj proj = {})
     const
	 {
	     if (first == last)
		 return last;
	     auto smallest = first;
	     while (++first != last)
		 if  (std::invoke(comp,  std::invoke(proj,   *first),	std::in-
     voke(proj, *smallest)))
		     smallest = first;
	     return smallest;
	 }

	 template<ranges::forward_range R, class Proj = std::identity,
		  std::indirect_strict_weak_order<
		      std::projected<ranges::iterator_t<R>,    Proj>>	Comp   =
     ranges::less>
	 constexpr ranges::borrowed_iterator_t<R>
	     operator()(R&& r, Comp comp = {}, Proj proj = {}) const
	 {
	     return  (*this)(ranges::begin(r),	ranges::end(r),  std::ref(comp),
     std::ref(proj));
	 } };

     inline constexpr min_element_fn min_element;

Example
     // Run this code

      #include <algorithm>
      #include <array>
      #include <cmath>
      #include <iostream>

      int main()
      {
	  namespace ranges = std::ranges;

	  std::array v{3, 1, -13, 1, 3, 7, -13};

	  auto iterator = ranges::min_element(v.begin(), v.end());
	  auto position = ranges::distance(v.begin(), iterator);
	  std::cout  <<  "min element is v[" << position << "] == " << *iterator
     << '\n';

	  auto	abs_compare  =	[](int	a,  int  b)  {	return	(std::abs(a)   <
     std::abs(b)); };
	  iterator = ranges::min_element(v, abs_compare);
	  position = ranges::distance(v.begin(), iterator);
	  std::cout << "|min| element is v[" << position << "] == " << *iterator
     << '\n';
      }

Output:
      min element is v[2] == -13
      |min| element is v[1] == 1

See also
	ranges::max_element    returns the largest element in a range
	(C++20) 	       (niebloid)
	ranges::minmax_element	returns the smallest and the largest elements in
     a range
	(C++20) 	       (niebloid)
	ranges::max	       returns the greater of the given values
	(C++20) 	       (niebloid)
	min_element	       returns the smallest element in a range
			       (function template)

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