How to detect which files need an update

[Ton Cardona]

I agree with you all in which dates, seconds and their conversions are 
a mess. If one could convert the seconds to the date it would be fine.

Sarah proposes a good solution; the trouble is I am dealing with some 
2.500 compressed  files, not with a few stacks ...

My FTP gives me the date and the time all right but files on a hard 
disk offer the modification date in  ... seconds for reasons I cannot 
wholly grasp

Thanks anyway to you all; the solution I have found is not ideal but it 
works reasonably well; the user can choose to update either today´s new 
files, last week´s or last month´s

Ton Cardona