strptime() equivalent on Windows?

Question

Is there a good equivalent implementation of strptime() available for Windows? Unfortunately, this POSIX function does not appear to be available.

Open Group description of strptime - summary: it converts a text string such as "MM-DD-YYYY HH:MM:SS" into a tm struct, the opposite of strftime().

Answer 1

If you don't want to port any code or condemn your project to boost, you can do this:

1. parse the date using sscanf
2. then copy the integers into a struct tm (subtract 1 from month and 1900 from year -- months are 0-11 and years start in 1900)
3. finally, use mktime to get a UTC epoch integer

Just remember to set the isdst member of the struct tm to -1, or else you'll have daylight savings issues.

Answer 2

Assuming you are using Visual Studio 2015 or above, you can use this as a drop-in replacement for strptime:

#include <time.h> #include <iomanip> #include <sstream>  extern "C" char* strptime(const char* s,                           const char* f,                           struct tm* tm) {   // Isn't the C++ standard lib nice? std::get_time is defined such that its   // format parameters are the exact same as strptime. Of course, we have to   // create a string stream first, and imbue it with the current C locale, and   // we also have to make sure we return the right things if it fails, or   // if it succeeds, but this is still far simpler an implementation than any   // of the versions in any of the C standard libraries.   std::istringstream input(s);   input.imbue(std::locale(setlocale(LC_ALL, nullptr)));   input >> std::get_time(tm, f);   if (input.fail()) {     return nullptr;   }   return (char*)(s + input.tellg()); } 

Just be aware that for cross platform applications, std::get_time wasn't implemented until GCC 5.1, so switching to calling std::get_time directly may not be an option.