CODEWITHSUNDEEP
c++datetime
Klaus
Klaus

Reputation: 25593

std::get_time did not parse day

If I try to set the day in a tm with std::get_time nothing happens but, input stream is in a fail state, which means that a parse error has been occured.

What is wrong with the following code?

{   // setting time works
    std::tm t{};
    std::istringstream ss("01:02:03");
    ss.imbue(std::locale("de_DE"));
    ss >> std::get_time(&t, "%H:%M:%S");
    std::cout << ss.fail() << std::endl;
    std::cout << std::put_time(&t, "%c") << '\n';
}   

{   // setting day of month did not work
    std::tm t{};
    std::istringstream ss("2");
    ss.imbue(std::locale("de_DE"));
    ss >> std::get_time(&t, "%d");
    std::cout << ss.fail() << std::endl;
    std::cout << std::put_time(&t, "%c") << '\n';
}

Output:

0 
Sun Jan  0 01:02:03 1900
1
Sun Jan  0 00:00:00 1900

Upvotes: 5

Views: 996

Answers (2)

Mike van Dyke
Mike van Dyke

Reputation: 2858

You need to pass a leading zero to the day:

std::istringstream ss("02");

EDIT: Now I notice that according to cppreference:

parses the day of the month as a decimal number (range [01,31]), leading zeroes permitted but not required.

Maybe it's a bug?

EDIT: Bug report here

Upvotes: 5

hellow
hellow

Reputation: 13420

I'm not quiet sure about this and I suspect, that this is a bug in your libstdc++ implementation.

Let's look at the documentation for %d specifier at cppreference

Parses the day of the month as a decimal number (range [01,31]), leading zeroes permitted but not required

Your code fails, but if you do instead this:

std::istringstream ss("02");

It will perfectly compile. When I try it on my local machine with g++ 5.4 it will produce the same error. You may try it with a newer gcc/libstdc++

Upvotes: 1

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