open a file based on the modified time

[anusha.boggarapu]

just a small idea of how to do this is enough:
how do we get modified time to be used in a program?? i am completely a begineer and dont have any idea about this.
suppose i have a directory with files stored using the time stamp when they were closed
abc.20090128113207.txt 1/28/2009 11:32 am
abc.20090129095319.txt 1/28/2009 06:04 pm
abc.20090130094034.txt 1/30/2009 11:04 am
abc.20090130110442.txt 1/30/2009 11:18 am
now in my program that i am designing user provides an input dd/mm/yyyy hh:mm and suppose he gives 01/28/2009 05:00 it should go to the second file
i have no idea of how to select that particular file based on the modified time
that is the modified time given by the user should be matched to the list of files based on the criteria i said above

any help will be very useful to me
thanks