0

I am trying to run a very simple example of the std::get_time() function but the parse is failing.

#include <iostream>
#include <sstream>
#include <locale>
#include <iomanip>
 
int main()
{
  std::tm                     t = {};
  std::istringstream          ss("04-02-2022 3:04:32");
  ss >> std::get_time(&t, "%m-%d-%Y %H:%M:%S");
  if (ss.fail()) {
    std::cout << "Parse failed\n";
    if ((ss.rdstate() & std::istringstream::failbit) != 0)
      std::cerr << "Error failbit\n";
    if ((ss.rdstate() & std::istringstream::goodbit) != 0)
      std::cerr << "Error goodbit\n";
    if ((ss.rdstate() & std::istringstream::eofbit) != 0)
      std::cerr << "Error eofbit\n";
    if ((ss.rdstate() & std::istringstream::badbit) != 0)
      std::cerr << "Error badbit\n";
  }
  else {
    std::cout << std::put_time(&t, "%c") << '\n';
  }
}

I am using Ubuntu 20.04 in Windows via WSL, which has g++ 9.4 installed, and I am compiling with the terminal command:

g++ -std=c++17 date.cpp -o date

The error is std::istringstream::failbit

Any Ideas what is going on?

Remy Lebeau
  • 555,201
  • 31
  • 458
  • 770
israel.sincro
  • 47
  • 9

1 Answers1

2

I was able to reproduce the failure in gcc 9.4. It works if you change 3 to 03 in the hour field.

Even though %H is not supposed to require a leading zero, this appears to be a gcc bug where it does. See Bug 78714. Despite being about %b, this comment in that ticket goes into detail about how it also affects %H and other placeholders, too.

The code works fine in gcc 12.1.
Demo

Remy Lebeau
  • 555,201
  • 31
  • 458
  • 770
  • that is correct.. i realized that later night and I just came in here to responde.. So thanks for the help. I was very troublesom, because the documentation explicitly say about the not need for the leading zeros. Thank you vey much @Remy – israel.sincro Jul 22 '22 at 13:13