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std::list::insert(3)	       C++ Standard Libary	    std::list::insert(3)

NAME
     std::list::insert - std::list::insert

Synopsis
	iterator insert( const_iterator pos, const T& value );		   (1)
	iterator  insert(  const_iterator pos, T&& value );		     (2)
     (since C++11)
	iterator insert( const_iterator pos,				   (3)
			 size_type count, const T& value );
	template< class InputIt >
	iterator insert( const_iterator pos, InputIt first, InputIt last   (4)
	);
	iterator insert( const_iterator pos,  std::initializer_list<T>	     (5)
     (since C++11)
	ilist );

	Inserts elements at the specified location in the container.

	1,2) Inserts value before pos.
	3) Inserts count copies of the value before pos.
	4) Inserts elements from range [first, last) before pos.

	This  overload	has  the  same	effect	as overload (3) if InputIt is an
     (until C++11)
	integral type.
	This overload participates in overload resolution only if InputIt
	qualifies as LegacyInputIterator, to avoid ambiguity with  the	overload
     (since C++11)
	(3).

	If first and last are iterators into *this, the behavior is undefined.
	5) Inserts elements from initializer list ilist before pos.

	No iterators or references are invalidated.

Parameters
	pos	     -	iterator  before which the content will be inserted (pos
     may be the
		      end() iterator)
	value	    - element value to insert
	count	    - number of elements to insert
	first, last - the range of elements to insert, cannot be iterators  into
     container
		      for which insert is called
	ilist	    - initializer list to insert the values from

Type requirements
	-
	T  must meet the requirements of CopyInsertable in order to use overload
     (1).
	-
	T must meet the requirements of MoveInsertable in order to use	overload
     (2).
	-
	T must meet the requirements of CopyAssignable and CopyInsertable in or-
     der to use
	overload (3).
	-
	T  must  meet  the  requirements of EmplaceConstructible in order to use
     overloads
	(4,5).

Return value
	1,2) Iterator pointing to the inserted value.
	3) Iterator pointing to the first element inserted, or pos if  count  ==
     0.
	4)  Iterator  pointing to the first element inserted, or pos if first ==
     last.
	5) Iterator pointing to the first element inserted, or pos if  ilist  is
     empty.

Complexity
	1,2) Constant.
	3) Linear in count.
	4) Linear in std::distance(first, last).
	5) Linear in ilist.size().

Exceptions
	If an exception is thrown for any reason, these functions have no effect
     (strong
	exception safety guarantee).

Example
     // Run this code

      #include <iostream>
      #include <iterator>
      #include <list>

      void print(int id, const std::list<int>& container)
      {
	  std::cout << id << ". ";
	  for (const int x : container)
	      std::cout << x << ' ';
	  std::cout << '\n';
      }

      int main ()
      {
	  std::list<int> c1(3, 100);
	  print(1, c1);

	  auto it = c1.begin();
	  it = c1.insert(it, 200);
	  print(2, c1);

	  c1.insert(it, 2, 300);
	  print(3, c1);

	  // reset `it` to the begin:
	  it = c1.begin();

	  std::list<int> c2(2, 400);
	  c1.insert(std::next(it, 2), c2.begin(), c2.end());
	  print(4, c1);

	  int arr[] = {501, 502, 503};
	  c1.insert(c1.begin(), arr, arr + std::size(arr));
	  print(5, c1);

	  c1.insert(c1.end(), {601, 602, 603});
	  print(6, c1);
      }

Output:
      1. 100 100 100
      2. 200 100 100 100
      3. 300 300 200 100 100 100
      4. 300 300 400 400 200 100 100 100
      5. 501 502 503 300 300 400 400 200 100 100 100
      6. 501 502 503 300 300 400 400 200 100 100 100 601 602 603

	Defect reports

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

	  DR	Applied to	   Behavior as published	    Correct  be-
     havior
	LWG 149 C++98	   overloads (3) and (4) returned nothing returns an it-
     erator

See also
	emplace    constructs element in-place
	(C++11)    (public member function)
	push_front inserts an element to the beginning
		   (public member function)
	push_back  adds an element to the end
		   (public member function)
	inserter    creates a std::insert_iterator of type inferred from the ar-
     gument
		   (function template)

http://cppreference.com 	   2024.06.10		    std::list::insert(3)
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