std optional: No such file or directory

Question

I tried to compile the following program with different compilers (including gcc 6.1) :

#include <optional>
int main()
{
    std::optional<int> o1;
}

Output is

main.cpp:1:20: fatal error: optional: No such file or directory #include optional

This is even true for the examples given here: http://en.cppreference.com/w/cpp/utility/optional/optional

Any clues why?

Do those "(since C++17)" marks ring a bell? – T.C. Jul 07 '16 at 19:41 — T.C., Jul 07 '16 at 19:41

score 24 · Accepted Answer · answered Jul 07 '16 at 19:42

24

std::optional will be part of the C++17 standard, but if you want to use before then you will have to use std::experimental::optional instead, available in the header <experimental/optional>.

answered Jul 07 '16 at 19:42

SirGuy

10,660
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36
66

2

Indeed, this works! -> #include int main() { std::experimental::optional o1;} – scoulomb Jul 07 '16 at 19:46

score 9 · Answer 2 · answered Jul 07 '16 at 19:43

9

It is in experimental (TS):

#include <experimental/optional>

example:

http://coliru.stacked-crooked.com/a/09ab8d1e51680a79

#include <experimental/optional>
#include <iostream>
int main()
{
    std::experimental::optional<int> o1;
}

answered Jul 07 '16 at 19:43

marcinj

48,511
9
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std optional: No such file or directory

2 Answers2

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