what does this line of code do?

New to RTCs and saw this bit of code and was wondering what it does.

  if (! RTC.isrunning()) {RTC.adjust(DateTime(__DATE__, __TIME__));}

Thank you,

Tony

I believe it first checks for a functioning RTC and then sets it to the time from the computer at the time it was complied.

Thank you.

sets it to the time from the computer at the time it was complied.

Note that this time will not be updated each time you run the code, only when it is compiled