Re: Update file
Robert Craig wrote:
>You can use the functions where() and seek() to position
>yourself in the file. Each open file has a "current position"
>based on reads and writes to the file. You can find out the
>current position using where(). You can set the current position
>using seek().
>Here's a simple example. It opens a file using "ub" - binary
>update mode. I think it's better to use binary mode than text
>mode, with seek() and where(), because in text mode you don't
>read \r characters, but they are still counted as far as the
>seek position is concerned, so things might get confusing. The
>example records the starting position of each line in the
>"test.dat" file. It is then able to pick a line at random and
>replace it with a string of X's. =
Hello Rob,
=46rom your example I deduce that in update mode a line can be replaced, =
but
only if the new line is exactly the same length as the old one. Is this t=
he
only way to work in update mode? Is it for instance not possible to inser=
t
a line in between other lines?
I know it is possible to append lines at the end of a file, but for that
purpose you also have the append mode.
Personally when I update a file, I first read them into (a) sequence(s),
close the file and after updating I open the file again for writing. Mayb=
e
this is more time-consuming, but when time is not that important, at the
beginning and end of a program.....
Sincerely,
Ad Rienks
email Ad_Rienks at compuserve.com
writing at 19:08 , =
on maandag 22 september 1997
Using EMail Assist for WinCIM
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