CODEWITHSUNDEEP
c++visual-c++c++17
Giuseppe Cesarano
Giuseppe Cesarano

Reputation: 53

std::from_chars doens't compile under MSVC

I have a little function that uses std::from_chars to create a date object from a std::string_view, while it compiles using clang or gcc under ubuntu it doesn't using msvc under windows.

date::year_month_day parseDate(const std::string_view& s)
{
    int y { 0 }, m { 0 }, d { 0 };

    std::from_chars(s.begin(), s.begin() + 4, y);
    std::from_chars(s.begin() + 5, s.begin() + 7, m);
    std::from_chars(s.begin() + 8, s.begin() + 10, d);

    return date::year { y } / m / d;
}

For each of std::from_chars call the following error is displayed at compile time:

'std::from_chars': none of the 14 overloads could convert all the argument types

The compiler then proceeds to make a list of possible overloads and i clearly see the one that I'm trying to use:

'std::from_chars_result std::from_chars(const char *const ,const char *const ,int &,const int) noexcept'

The last parameter has a default value. Can someone explain me what I'm doing wrong?

Upvotes: 2

Views: 1190

Answers (2)

Ian Cook
Ian Cook

Reputation: 1196

The other answer is correct - from_chars doesn't play nicely with string_view.

However, for others finding the same issue in future, there is a proposal to add the relevant overloads to from_chars.

Progress on this can be tracked here.

Upvotes: 3

Giuseppe Cesarano
Giuseppe Cesarano

Reputation: 53

As mentioned by Some programmer dude and Ruks, std::string_view.begin() doesn't return a const char *const, std::string_view.data() was the method i was looking for.

Upvotes: 2

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