easy way to modify textfile

[Gunnar G]

Hello.
If I wish to open a huge textfile and only change the 300th line in the
file, how do I do that?

[Maxim Yegorushkin]

On Wed, 06 Jul 2005 11:49:13 +0400, Gunnar G <de****@comhem. se> wrote:

If I wish to open a huge textfile and only change the 300th line in the
file, how do I do that?

Use a stream editor, such as sed.

--
Maxim Yegorushkin
<fi************ ****@gmail.com>

[Gunnar G]

> Use a stream editor, such as sed.
And if that is not an option?
I solved it by storing all the lines in a vector, then reopen the file in
non-appending mode and write all the lines.

There must be a better way...

[Maxim Yegorushkin]

On Wed, 06 Jul 2005 12:23:18 +0400, Gunnar G <de****@comhem. se> wrote:

Use a stream editor, such as sed.

And if that is not an option?
I solved it by storing all the lines in a vector, then reopen the file in
non-appending mode and write all the lines.

There must be a better way...

You could read the file by chunks in a buffer rather then reading the
whole in the vector. This way you avoid all the problems related to memory
allocation.

--
Maxim Yegorushkin
<fi************ ****@gmail.com>

[Karl Heinz Buchegger]

Gunnar G wrote:

Hello.
If I wish to open a huge textfile and only change the 300th line in the
file, how do I do that?

open input file
open a new file for output

counter = 0;

while( line can be read from input ) {
increment counter
if counter equals 300
write replacement line to output
else
write original line to output
}

close input file
close output file
delete input file
rename output file to the input file name

done

--
Karl Heinz Buchegger
kb******@gascad .at

[Panjandrum]

Gunnar G wrote:

Use a stream editor, such as sed.

And if that is not an option?
I solved it by storing all the lines in a vector, then reopen the file in
non-appending mode and write all the lines.

There must be a better way...

If the line isn't longer or shorter afterwards you can use random
access.