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std::fill(3)		      C++ Standard Libary		  std::fill(3)

NAME
       std::fill - std::fill

Synopsis
	  Defined in header <algorithm>
	  template<  class  ForwardIt,	class  T >		    (constexpr
       since
	  void fill( ForwardIt first, ForwardIt	last,		C++20)
	  const	T& value );					(until C++26)
	  template< class ForwardIt, class T = typename
	  std::iterator_traits

	   <ForwardIt>::value_type >				(since C++26)
	  constexpr void fill( ForwardIt first,
	  ForwardIt last,

			       const T&	value );
	  template< class ExecutionPolicy, class
	  ForwardIt, class T >
							(1)
       (since C++17)
	  void		 fill(		  ExecutionPolicy&&	       policy,
       (until C++26)

		     ForwardIt first, ForwardIt	last,
	  const	T& value );
	  template< class ExecutionPolicy,
							    (2)
		    class ForwardIt, class T = typename
	  std::iterator_traits
										 (since
       C++26)
	   <ForwardIt>::value_type >
	  void fill( ExecutionPolicy&& policy,

		     ForwardIt first, ForwardIt	last,
	  const	T& value );

	  1)  Assigns  the  given  value  to all elements in the range [first,
       last).
	  2) Same as (1), but executed according to policy.
	  This overload	participates in	overload resolution only if

	  std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>  is	 true.
       (until
										    C++20)
	  std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>  is
       true. (since
										    C++20)

	  If value is not writable to first, the program is ill-formed.

Parameters
	  first, last -	the range of elements to modify
	  value	      -	the value to be	assigned
	  policy      -	the execution policy to	use. See execution policy  for
       details.

Type requirements
	  -
	  ForwardIt must meet the requirements of LegacyForwardIterator.

Complexity
	  Exactly std::distance(first, last) assignments.

Exceptions
	  The overload with a template parameter named ExecutionPolicy reports
       errors as
	  follows:

	    *  If  execution  of  a  function invoked as part of the algorithm
       throws an exception
	      and ExecutionPolicy is one of the	standard policies, std::termi-
       nate is called.
	      For any other ExecutionPolicy, the behavior  is  implementation-
       defined.
	    *  If  the	algorithm  fails to allocate memory, std::bad_alloc is
       thrown.

Possible implementation
					    fill
	  template<class ForwardIt,
		   class    T	  =	typename     std::iterator_traits<For-
       wardIt>::value_type>
	  void fill(ForwardIt first, ForwardIt last, const T& value)
	  {
	      for (; first != last; ++first)
		  *first = value;
	  }

Notes
		    Feature-test       macro		     Value	   Std
       Feature
	  __cpp_lib_algorithm_default_value_type 202403	(C++26)	 List-initial-
       ization for
								algorithms
       (1,2)

Example
       // Run this code

	#include <algorithm>
	#include <complex>
	#include <iostream>
	#include <vector>

	void println(const auto& seq)
	{
	    for	(const auto& e : seq)
		std::cout << e << ' ';
	    std::cout << '\n';
	}

	int main()
	{
	    std::vector<int> v{0, 1, 2,	3, 4, 5, 6, 7, 8};
	    println(v);

	    // set all of the elements to 8
	    std::fill(v.begin(), v.end(), 8);
	    println(v);

	    std::vector<std::complex<double>> nums{{1, 3}, {2, 2}, {4, 8}};
	    println(nums);
	    #ifdef __cpp_lib_algorithm_default_value_type
		std::fill(nums.begin(),	nums.end(), {4,	2});
	    #else
		std::fill(nums.begin(),	  nums.end(),  std::complex<double>{4,
       2});
	    #endif
	    println(nums);
	}

Output:
	0 1 2 3	4 5 6 7	8
	8 8 8 8	8 8 8 8	8
	(1,3) (2,2) (4,8)
	(4,2) (4,2) (4,2)

	  Defect reports

	  The following	behavior-changing defect reports were applied retroac-
       tively to
	  previously published C++ standards.

	    DR	  Applied to	     Behavior as published		  Cor-
       rect behavior
			     T	was  required to be CopyAssignable,   required
       to be writable
	  LWG 283 C++98	     but				    instead
			     T is not always writable to ForwardIt

See also
	  fill_n       copy-assigns the	given value to N elements in a range
		       (function template)
	  copy	       copies a	range of elements to a new location
	  copy_if      (function template)
	  (C++11)
		       assigns the results of  successive  function  calls  to
       every element in	a
	  generate     range
		       (function template)
		       applies	a function to a	range of elements, storing re-
       sults in	a
	  transform    destination range
		       (function template)
	  ranges::fill assigns a range of elements a certain value
	  (C++20)      (niebloid)

http://cppreference.com		  2024.06.10			  std::fill(3)

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