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std::make_optional(3)	       C++ Standard Libary	   std::make_optional(3)

NAME
     std::make_optional - std::make_optional

Synopsis
	Defined in header <optional>
	template< class T >
	constexpr  std::optional<std::decay_t<T>>  make_optional( T&& value  (1)
     (since C++17)
	);
	template< class T, class... Args  >				     (2)
     (since C++17)
	constexpr std::optional<T> make_optional( Args&&... args );
	template< class T, class U, class... Args >

	constexpr  std::optional<T>  make_optional( std::initializer_list<U> (3)
     (since C++17)
	il,

						  Args&&... args );

	1) Creates an optional object from value. Effectively calls
	std::optional<std::decay_t<T>>(std::forward<T>(value)).
	2) Creates an optional object constructed in-place from args.... Equiva-
     lent to
	return std::optional<T>(std::in_place, std::forward<Args>(args)...);.
	3) Creates an optional object constructed in-place from il and	args....
     Equivalent
	to	return	   std::optional<T>(std::in_place,     il,     std::for-
     ward<Args>(args)...);.

Parameters
	value	 - the value to construct optional object with
	il, args - arguments to be passed to the constructor of T

Return value
	The constructed optional object.

Exceptions
	Throws any exception thrown by the constructor of T.

Notes
	T need not be movable for overloads (2,3) due to  guaranteed  copy  eli-
     sion.

Example
     // Run this code

      #include <iomanip>
      #include <iostream>
      #include <optional>
      #include <string>
      #include <vector>

      int main()
      {
	  auto op1 = std::make_optional<std::vector<char>>({'a','b','c'});
	  std::cout << "op1: ";
	  for (char c : op1.value())
	      std::cout << c << ',';
	  auto op2 = std::make_optional<std::vector<int>>(5, 2);
	  std::cout << "\nop2: ";
	  for (int i : *op2)
	      std::cout << i << ',';
	  std::string str{"hello world"};
	  auto op3 = std::make_optional<std::string>(std::move(str));
	  std::cout  << "\nop3: " << std::quoted(op3.value_or("empty value")) <<
     '\n';
	  std::cout << "str: " << std::quoted(str) << '\n';
      }

Possible output:
      op1: a,b,c,
      op2: 2,2,2,2,2,
      op3: "hello world"
      str: ""

See also
	constructor   constructs the optional object
		      (public member function)

http://cppreference.com 	   2024.06.10		   std::make_optional(3)
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