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std::queue::emplace(3)	       C++ Standard Libary	  std::queue::emplace(3)

NAME
     std::queue::emplace - std::queue::emplace

Synopsis
	template< class... Args >		   (since C++11)
	void emplace( Args&&... args ); 	   (until C++17)
	template< class... Args >		   (since C++17)
	decltype(auto) emplace( Args&&... args );

	Pushes a new element to the end of the queue. The element is constructed
     in-place,
	i.e.  no  copy	or move operations are performed. The constructor of the
     element is
	called with exactly the same arguments as supplied to the function.

	Effectively calls c.emplace_back(std::forward<Args>(args)...);.

Parameters
	args - arguments to forward to the constructor of the element

Return value
	(none)
     (until C++17)
	The  value  or	reference,  if	any,  returned	by  the  above	call  to
     (since C++17)
	Container::emplace_back.

Complexity
	Identical to the complexity of Container::emplace_back.

Example
     // Run this code

      #include <iostream>
      #include <queue>

      struct S
      {
	  int id;

	  S(int i, double d, std::string s) : id{i}
	  {
	      std::cout << "S::S(" << i << ", " << d << ", \"" << s << "\");\n";
	  }
      };

      int main()
      {
	  std::queue<S> queue;
	  const S& s = queue.emplace(42, 3.14, "C++"); // for return value C++17
     required
	  std::cout << "id = " << s.id << '\n';
      }

Output:
      S::S(42, 3.14, "C++")
      id = 42

       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 2783 C++17	    emplace returned  reference,  breaking	 returns
     decltype(auto)
			    compatibility with pre-C++17 containers

See also
	push inserts element at the end
	     (public member function)
	pop  removes the first element
	     (public member function)

http://cppreference.com 	   2024.06.10		  std::queue::emplace(3)
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