Implementing "date" in C

[drimades]

This is part of the "date.c" program:
...

out[0] = '\1';

if (rfc_format)
setlocale (LC_ALL, "C");

done = (nstrftime (out, out_length, format, tm, 0, when.tv_nsec) || out[0] == '\0');

...

How is defined nstrftime() and how it works in this case?

[strick94u]

I would just ask some nice girl out on a date if I were you