Is there a standard date/time class in C++?

Question

Does C++ stl have a standard time class? Or do I have to convert to c-string before writing to a stream. Example, I want to output the current date/time to a string stream:

 time_t tm(); ostringstream sout; sout << tm << ends; 

In this case I get the current date/time written out as a number without any formatting. I can use c- runtime function strftime to format tm first, but that seems like it should not be necessary if the stl has a time class that can be instantiated from time_t value

Answer 1

Not part of STL but well known library is boost.

I would go the way of using boost::date. Here are some examples: http://www.boost.org/doc/libs/1_55_0/doc/html/date_time/date_time_io.html#date_time.io_tutorial.

If you did not try out boost yet I encourage you to do so as it saves you from a lot of nasty issues, as it masks most OS dependent things like threading for example. Many things in boost are header only (template libraries). However datetime requires a lib or dll.

Answer 2

EDIT

The standard "datetime" class is std::chrono::time_point since C++11. The code in the question should be roughly equivalent to

const auto now = std::chrono::system_clock::now(); const auto t_c = std::chrono::system_clock::to_time_t(now); std::cout << std::put_time(std::localtime(&t_c), "%F %T.\n"); 

OLD ANSWER

Nitpicking: The STL being the Standard Template Library deals with generic container and algorithms etc. and is unlikely to incorporate classes for date handling and calculation even in the future…

The C++ Standard Library itself includes the STL and a previous version of the C standard library. The latter offers some date and time related functions via #include <ctime> which has already been mentioned above.

If wrapping (or simply using) these functions is sufficient (and quicker) than pulling in boost, go with these. There is nothing wrong with them.