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

      From cppreference.com
      <cpp‎ |container‎ |multimap

      [edit template]
       
       
       
      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)
       
      template<class C2>
      void merge(std::map<Key, T, C2, Allocator>& source);
      (1)(since C++17)
      (constexpr since C++26)
      template<class C2>
      void merge(std::map<Key, T, C2, Allocator>&& source);
      (2)(since C++17)
      (constexpr since C++26)
      template<class C2>
      void merge(std::multimap<Key, T, C2, Allocator>& source);
      (3)(since C++17)
      (constexpr since C++26)
      template<class C2>
      void merge(std::multimap<Key, T, C2, Allocator>&& source);
      (4)(since C++17)
      (constexpr since C++26)

      Attempts to extract (“splice”) each element insource and insert it into*this using the comparison object of*this.

      Ifget_allocator()== source.get_allocator() isfalse, the behavior is undefined.

      No elements are copied or moved, only the internal pointers of the container nodes are repointed. All pointers and references to the transferred elements remain valid, but now refer into*this, not intosource.

      Contents

      [edit]Parameters

      source - compatible container to transfer the nodes from

      Exceptions

      Does not throw unless comparison throws.

      [edit]Complexity

      Given\(\scriptsize S\)S assize() and\(\scriptsize N\)N assource.size():

      1-4)\(\scriptsize S \cdot \log(S + N)\)S·log(S+N)

      [edit]Example

      Run this code
      #include <iostream>#include <map>#include <string> int main(){std::multimap<int,std::string> ma{{1,"apple"},{5,"pear"},{10,"banana"}};std::multimap<int,std::string> mb{{2,"zorro"},{4,"batman"},{5,"X"},{8,"alpaca"}};std::multimap<int,std::string> u;    u.merge(ma);std::cout<<"ma.size(): "<< ma.size()<<'\n';    u.merge(mb);std::cout<<"mb.size(): "<< mb.size()<<'\n'; for(constauto& kv: u)std::cout<< kv.first<<", "<< kv.second<<'\n';}

      Output:

      ma.size(): 0mb.size(): 01, apple2, zorro4, batman5, pear5, X8, alpaca10, banana

      [edit]See also

      (C++17)
      extracts nodes from the container
      (public member function)[edit]
      inserts elementsor nodes(since C++17)
      (public member function)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/container/multimap/merge&oldid=135732"

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