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      std::multimap<Key,T,Compare,Allocator>::insert

      From cppreference.com
      <cpp‎ |container‎ |multimap
       
       
       
      std::multimap
      Member functions
      Non-member functions
      (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
      Deduction guides(C++17)
       
      iterator insert(const value_type& value);
      		 (1)
      iterator insert( value_type&& value);
      		 (2)(since C++17)
      template<class P>
      iterator insert( P&& value);
      		 (3)(since C++11)
      (4)
      iterator insert( iterator pos,const value_type& value);
      		(until C++11)
      iterator insert( const_iterator pos,const value_type& value);
      		(since C++11)
      iterator insert( const_iterator pos, value_type&& value);
      		 (5)(since C++17)
      template<class P>
      iterator insert( const_iterator pos, P&& value);
      		 (6)(since C++11)
      template<class InputIt>
      void insert( InputIt first, InputIt last);
      		 (7)
      void insert(std::initializer_list<value_type> ilist);
      		 (8)(since C++11)
      iterator insert( node_type&& nh);
      		 (9)(since C++17)
      iterator insert( const_iterator pos, node_type&& nh);
      		 (10)(since C++17)

      Inserts element(s) into the container.

      1-3) Insertsvalue. If the container has elements with equivalent key, inserts at the upper bound of that range.
      Overload(3) is equivalent toemplace(std::forward<P>(value)) and only participates in overload resolution ifstd::is_constructible<value_type, P&&>::value==true.
      4-6) Insertsvalue in the position as close as possible to the position just prior topos.
      Overload(6) is equivalent toemplace_hint(hint,std::forward<P>(value)) and only participates in overload resolution ifstd::is_constructible<value_type, P&&>::value==true.
      7) Inserts elements from range[first, last).
      8) Inserts elements from initializer listilist.
      9) Ifnh is an emptynode handle, does nothing. Otherwise, inserts the element owned bynh into the container and returns an iterator pointing at the inserted element. If a range containing elements with keys equivalent tonh.key() exists in the container, the element is inserted at the end of that range. The behavior is undefined ifnh is not empty andget_allocator()!= nh.get_allocator().
      10) Ifnh is an emptynode handle, does nothing and returns the end iterator. Otherwise, inserts the element owned bynh into the container, and returns the iterator pointing to the element with key equivalent tonh.key(). The element is inserted as close as possible to the position just prior topos. The behavior is undefined ifnh is not empty andget_allocator()!= nh.get_allocator().

      No iterators or references are invalidated.If the insertion is successful, pointers and references to the element obtained while it is held in the node handle are invalidated, and pointers and references obtained to that element before it was extracted become valid.(since C++17)

      Contents

      [edit]Parameters

      pos - iterator to the position before which the new element will be inserted
      value - element value to insert
      first, last - the pair of iterators defining the sourcerange of elements to insert
      ilist - initializer list to insert the values from
      nh - a compatiblenode handle
      Type requirements
      -
      InputIt must meet the requirements ofLegacyInputIterator.

      [edit]Return value

      1-6) An iterator to the inserted element.
      7,8) (none)
      9,10) End iterator ifnh was empty, iterator pointing to the inserted element otherwise.

      [edit]Exceptions

      1-6) If an exception is thrown by any operation, the insertion has no effect.
      7,8) No exception safety guarantee.
      9,10) If an exception is thrown by any operation, the insertion has no effect.

      [edit]Complexity

      1-3)O(log(size()))
      4-6) Amortized constant if the insertion happens in the position just beforepos,O(log(size())) otherwise.
      7,8)O(N·log(size() + N)), whereN is the number of elements to insert.
      9)O(log(size()))
      10) Amortized constant if the insertion happens in the position just beforepos,O(log(size())) otherwise.

      [edit]Example

      Run this code
      #include <functional>#include <iostream>#include <map>#include <string>#include <string_view>#include <utility> template<class M>void print(conststd::string_view rem,const M& mmap){std::cout<< rem<<' ';for(constauto& e: mmap)std::cout<<'{'<< e.first<<','<< e.second<<"} ";std::cout<<'\n';} int main(){// list-initializestd::multimap<int,std::string,std::greater<int>> mmap{{2,"foo"},{2,"bar"},{3,"baz"},{1,"abc"},{5,"def"}};    print("#1", mmap); // insert using value_type    mmap.insert(decltype(mmap)::value_type(5,"pqr"));    print("#2", mmap); // insert using pair    mmap.insert(std::pair{6,"uvw"});    print("#3", mmap);     mmap.insert({7,"xyz"});    print("#4", mmap); // insert using initializer_list    mmap.insert({{5,"one"},{5,"two"}});    print("#5", mmap); // insert using a pair of iterators    mmap.clear();constauto il={std::pair{1,"ä"},{2,"ё"},{2,"ö"},{3,"ü"}};    mmap.insert(il.begin(), il.end());    print("#6", mmap);}

      Output:

      #1 {5,def} {3,baz} {2,foo} {2,bar} {1,abc}#2 {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}#3 {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}#4 {7,xyz} {6,uvw} {5,def} {5,pqr} {3,baz} {2,foo} {2,bar} {1,abc}#5 {7,xyz} {6,uvw} {5,def} {5,pqr} {5,one} {5,two} {3,baz} {2,foo} {2,bar} {1,abc}#6 {3,ü} {2,ё} {2,ö} {1,ä}

      [edit]Defect reports

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

      DRApplied toBehavior as publishedCorrect behavior
      LWG 233C++98pos was just a hint, it could be totally ignoredthe insertion is required to
      be as close as possible to the
      position just prior topos
      LWG 264C++98the complexity of overload(5) was required to be linear if
      the range[first, last) is sorted according toCompare      		removed the linear requirement
      in this special case
      LWG 371C++98the order of equivalent elements
      was not guaranteed to be preserved      		required to be preserved
      LWG 2005C++11overloads(3,6) were poorly describedimproved the description

      [edit]See also

      (C++11)
      		 constructs element in-place
      (public member function)[edit]
      constructs elements in-place using a hint
      (public member function)[edit]
      creates astd::insert_iterator of type inferred from the argument
      (function template)[edit]
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