1. files...
- Posted by MiCkeY <mickeysc at ZAZ.COM.BR>
Dec 23, 1999
-
Last edited Dec 24, 1999
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Is it possible to:
1=BA) delete a line (or more) of a file without copy all the file except =
the lines I want to delete?
2=BA) read, ie, 10 lines of a file using gets() and after return to the =
line 1 without have to close and open the file again?
Thanks,
Lu=EDs Fernando
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content=3D"text/html; charset=3Diso-8859-1" =
http-equiv=3DContent-Type>
<META content=3D"MSHTML 5.00.2614.3500" name=3DGENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Is it possible to:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>1=BA) delete a line (or more) of a file =
without copy=20
all the file except the lines I want to delete?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>2=BA) read, ie, 10 lines of a file =
using gets() and=20
after return to the line 1 without have to close and open the file=20
again?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Lu=EDs =
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2. Re: files...
- Posted by JJProg at CYBERBURY.NET
Dec 24, 1999
>Is it possible to:
>1º) delete a line (or more) of a file without copy all the file except the
>lines I want to delete?
>2º) read, ie, 10 lines of a file using gets() and after return to the line 1
>without have to close and open the file again?
>Thanks,
>Luís Fernando
To answer your second question:
You can use seek in file.e to return to the beginning of the file
without closing it and opening it again.
As far as I know, there is no really simple way to do what you are
asking in your first question. If you know the position in the file of
where you want to start deleting and where you want to end, you can use
seek and only copy the second half of the file. If the file you are
writing can have extra whitespace - an INI file, for example, you could replace
the line you are trying to delete with spaces or newline characters.
Jeffrey Fielding
JJProg at cyberbury.net
http://members.tripod.com/~JJProg/
3. Re: files...
On Thu, 23 Dec 1999, MiCkey wrote:
> >%_Is it possible to:
>
> 1º) delete a line (or more) of a file without copy all the file except the
> lines I want to delete?
>
> 2º) read, ie, 10 lines of a file using gets() and after return to the line 1
> without have to close and open the file again?
>
> Thanks,
> Luís Fernando
If you mean a text file containing random-length lines, the only way is to
read the data in, remove the lines, and write the data back to the file.
This is true of any language that can write "text" files.
You can do this one line at a time, reading the old file and writing to a new
file. If the file is not larger than the memory in your computer, then you
can read the entire file into a sequence, remove lines from the sequence,
and write the entire file back to disk. This is much faster than the one-line
at a time method.
sequence s
object line
integer fn
s = {}
fn = open("dbase.html","r") -- read mode
while 1 do
line = gets(fn)
if atom(line) then exit -- EOF
else s = append(s,line)
end if
end while
close(fn)
-- s will contain the lines: s[1] is line 1, s[20] is line 20.....
-- do your deletions here, the write the lines back using a
-- loop:
fn = open("dbase.html","w") -- write mode
for i = 1 to length(s) do
puts(fn,s[i]])
end for
close(fn)
Regards,
Irv
