Is there something in the standard C/C++ libraries which will populate a struct tm?
To be more specific about my problem: I want to be able to provide a date and populate the struct tm from that (for example: 1-1-2000 00:00:01.) For most of the fields I can just directly insert the data, but I just don't know tm_wday and tm_isdst.
I'm really looking for a way to populate those two without writing some complex day of the week state machine.
mktime sounds like your best bet. The struct tm you pass to it need not have values in the specified ranges; it normalizes the fields, including recalculating tm_wday and tm_yday. To have it attempt to determine if DST is in effect, set the tm_isdst member to negative before you call mktime.
If you are converting from a string, you can use the get_time manipulator to extract the information into a tm.