It's been bugging me for some time, but it's a pretty basic problem really.

e.g.
type students = record
....
....
file1 = file of student

var student: students;
dat: file1;
....


As you can see here, I have a data file that is a file of a record.
My problem is - I have a procedure for adding students and it works fine. But the program needs to have a procedure (it doesn't HAVE to be a procedure) in which you change their data (e.g. address, phone number etc.) and I'm just stuck.

Can you even change stuff once it's all written in the file? How?
If not, how should I get around the problem?

Thanks!