How to initialize C++17 vector of pairs with optional element

user_389823 0
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In C++17, how do you declare and initialize a vector of pairs(or tuples) with an optional element?

    std::vector<std::pair<int, optional<bool> > > vec1 = { {1, true},
                                                           {2, false}, 
                                                           {3, nullptr}};

I have a pair where the second element may be null/optional.

option-type c++17 std-pair vector c++
2 Answers

You are looking for std::nullopt instead of nullptr.

std::vector<std::pair<int, std::optional<bool> > > vec1 =
  { {1, true}, {2,false}, {3,std::nullopt} };
user_4307660

Or simple use default construction:

std::vector<std::pair<int, std::optional<bool>>> vec1 {
    {1, true}, {2,false}, {3,{}}
};
user_13874380
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