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C++ std::optional

Holo the Drunk answered on February 22, 2022 Popularity 10/10 Helpfulness 2/10

answer C++ std::optional

related std::optional

C++ std::optional

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std::optional<std::string> gojira(bool present) {
	return present ? "angy" : {};
}

Popularity 10/10 Helpfulness 2/10 Language cpp

Source: Grepper

Tags: c++

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Contributed on Feb 22 2022

Holo the Drunk

0 Answers Avg Quality 2/10

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std::optional

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#include <iostream>
#include <optional>
#include <string>
 
int main()
{
    std::optional<int> o1, // empty
                       o2 = 1, // init from rvalue
                       o3 = o2; // copy-constructor
 
    // calls std::string( initializer_list<CharT> ) constructor
    std::optional<std::string> o4(std::in_place, {'a', 'b', 'c'});
 
    // calls std::string( size_type count, CharT ch ) constructor
    std::optional<std::string> o5(std::in_place, 3, 'A');
 
    // Move-constructed from std::string using deduction guide to pick the type
 
    std::optional o6(std::string{"deduction"});
 
    std::cout << *o1 << ' ' << *o2 << ' ' << *o3 << ' ' << *o4 << ' ' << *o5  << ' ' << *o6 << '\n';
}

Popularity 7/10 Helpfulness 4/10 Language cpp

Source: en.cppreference.com

Tags: c++

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