OpenEuphoria

Re: opening and writing files...

• Posted by Graeme <graemeburke at CROSSWINDS.NET> Jan 12, 2001
• 426 views

At 04:25 AM 11/01/01 -0800, you wrote:
>Heya all!
>
>Me again, this time i'm wondering this: When I open a file for write,
>it gets set to 0, I open a file for append, it starts at EOF, I open a file
>for update, it lets me seek around, but when I write bytes to the file
>at specific points, instead of adding the characters to the file, it
>overwrites whatever is there.
>
>How can I get it so that I can seek to a part of the file, and add
>characters? Again, I don't have these files in memory (trying to
>make the footprint during usage as tiny as possible)
>
>TIA,
>
>--"LEVIATHAN"
>
>


Here's one that moves the end of the file and
inserts the data at the specified offset.

It does it one byte at a time for low mem usage
(as requested), so it's going to be tragicly slow
if you want to insert data at the start of a big
file. Anyway, here it is.

Graeme.



--UNTESTED

include file.e

procedure insert_data(sequence path,
                     integer offset,
                     sequence data)

    --insert data n at offset
    integer fn,
            gap,c

    gap=length(data)
    fn=open(path,"ub")

    if seek(fn,-1) then end if -- goto EOF

    -- move end of file
    for x=where(fn)+gap-1 to offset+gap by -1 do
        if seek(fn,x-gap) then end if
        c=getc(fn)
        if seek(fn,x) then end if
        puts(fn,c)
    end for

    --write data
    if seek(fn,offset) then end if
    puts(fn,data)
    close(fn)
end procedure





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