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std::function::target(3)       C++ Standard Libary	std::function::target(3)

NAME
     std::function::target - std::function::target

Synopsis
	template< class T >		  (1) (since C++11)
	T* target() noexcept;
	template< class T >		  (2) (since C++11)
	const T* target() const noexcept;

	Returns a pointer to the stored callable function target.

Parameters
	(none)

Return value
	A  pointer  to the stored function if target_type() == typeid(T), other-
     wise a null
	pointer.

Example
     // Run this code

      #include <functional>
      #include <iostream>

      int f(int, int) { return 1; }
      int g(int, int) { return 2; }
      void test(std::function<int(int, int)> const& arg)
      {
	  std::cout << "test function: ";
	  if (arg.target<std::plus<int>>())
	      std::cout << "it is plus\n";
	  if (arg.target<std::minus<int>>())
	      std::cout << "it is minus\n";

	  int (*const* ptr)(int, int) = arg.target<int(*)(int, int)>();
	  if (ptr && *ptr == f)
	      std::cout << "it is the function f\n";
	  if (ptr && *ptr == g)
	      std::cout << "it is the function g\n";
      }

      int main()
      {
	  test(std::function<int(int, int)>(std::plus<int>()));
	  test(std::function<int(int, int)>(std::minus<int>()));
	  test(std::function<int(int, int)>(f));
	  test(std::function<int(int, int)>(g));
      }

Output:
      test function: it is plus
      test function: it is minus
      test function: it is the function f
      test function: it is the function g

	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 2591 C++11	    the behavior is undefined if T is	 behavior is de-
     fined (always
			    not     Callable				 returns
     nullptr)

See also
	target_type obtains the typeid of the stored target
		    (public member function)

http://cppreference.com 	   2024.06.10		std::function::target(3)
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