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std::any::has_value(3)	      C++ Standard Libary	std::any::has_value(3)

NAME
       std::any::has_value - std::any::has_value

Synopsis
	  bool has_value() const noexcept;  (since C++17)

	  Checks whether the object contains a value.

Parameters
	  (none)

Return value
	  true if instance contains a value, otherwise false.

Example
       // Run this code

	#include <any>
	#include <iostream>
	#include <string>

	int main()
	{
	    std::boolalpha(std::cout);

	    std::any a0;
	    std::cout << "a0.has_value(): " << a0.has_value() << "\n";

	    std::any a1	= 42;
	    std::cout << "a1.has_value(): " << a1.has_value() << '\n';
	    std::cout << "a1 = " << std::any_cast<int>(a1) << '\n';
	    a1.reset();
	    std::cout << "a1.has_value(): " << a1.has_value() << '\n';

	    auto a2 = std::make_any<std::string>("Milky	Way");
	    std::cout << "a2.has_value(): " << a2.has_value() << '\n';
	    std::cout  <<  "a2	=  \""	<<  std::any_cast<std::string&>(a2) <<
       "\"\n";
	    a2.reset();
	    std::cout << "a2.has_value(): " << a2.has_value() << '\n';
	}

Output:
	a0.has_value():	false
	a1.has_value():	true
	a1 = 42
	a1.has_value():	false
	a2.has_value():	true
	a2 = "Milky Way"
	a2.has_value():	false

See also
	  reset	destroys contained object
		(public	member function)

http://cppreference.com		  2022.07.31		std::any::has_value(3)

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