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

NAME
     std::deque::insert - std::deque::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.

	All iterators (including the end() iterator) are invalidated. References
     are
	invalidated  too,  unless  pos == begin() or pos == end(), in which case
     they are not
	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 CopyAssignable and CopyInsertable in or-
     der to use
	overload (1).
	-
	T must meet the requirements of MoveAssignable and MoveInsertable in or-
     der 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).
	-
	T must meet the  requirements  of  Swappable,  MoveAssignable,	MoveCon-
     structible and
	MoveInsertable in order to use overloads (4,5). (since C++17)

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 plus linear in the lesser of the distances between pos and
     either of
	the ends of the container.
	3) Linear in count plus linear in the lesser of  the  distances  between
     pos and either
	of the ends of the container.
	4) Linear in std::distance(first, last) plus linear in the lesser of the
     distances
	between pos and either of the ends of the container.
	5) Linear in ilist.size() plus linear in the lesser of the distances be-
     tween pos and
	either of the ends of the container.

Exceptions
	If an exception is thrown other than by

	  * the copy constructor of T,

	  * the move constructor of T,	 (since C++11)

	  * the copy assignment operator of T,

	  * the move assignment operator of T,	 (since C++11)

	this function has no effect (strong exception guarantee).

	If an exception is thrown when inserting a single element at either
	end,   this   function	has  no  effect  (strong  exception  guarantee).
     (since C++11)
	Otherwise, if an exception is thrown by the move constructor of a
	non-CopyInsertable T, the effects are unspecified.

Example
     // Run this code

      #include <iostream>
      #include <iterator>
      #include <deque>

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

      int main ()
      {
	  std::deque<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::deque<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
     behavior
	LWG 149 C++98	   overloads (3) and (4) returned	returns an iter-
     ator
			   nothing
	LWG 247 C++98	   the complexity was only specified	 also  specified
     for inserting
			   for	inserting  a  single element	   multiple ele-
     ments

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::deque::insert(3)
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