(w oparciu o wpis @Snejki)
string date = DateTime.Now.ToString("dd.MM.yyyy");
string time = DateTime.Now.ToString("hh:mm.ss");
string full_name = Imieinazw.Text;
sw = new StreamWriter(path, true);
sw.WriteLine("{0};{1};{2}",full_name,date,time);
sw.Close();
lub
string full_name = Imieinazw.Text;
sw = new StreamWriter(path, true);
sw.WriteLine("{0};{1:dd.MM.yyyy};{1:hh:mm.ss}",full_name,DateTime.Now);
sw.Close();
lub
sw = new StreamWriter(path, true);
sw.WriteLine("{0};{1:dd.MM.yyyy};{1:hh:mm.ss}",Imieinazw.Text,DateTime.Now);
sw.Close();
[ String Class ] [ Composite formatting ] [ DateTime.Now ]