Delete or trim end of text file

[Anon]

Hi there,

I have a text file that's written to in a simple Flash/PHP chat room I've developed. The one thing I haven't worked out is how to limit the lines within the text file, so that once it reaches a certain number, any that fall below that (ie. the older messages) are deleted from the file. I would presume this could be added somewhere in the PHP that writes the new post to the top of the file.
Each message appears on one line.

Can anyone help me?

Thanks
Dave

[Anon]

Sure. Read in your text file to an array (using file() ) and do what you want with the contents: adding new content to the top of the file, deleting trailing older lines, etc. Just be aware (you probably already know this) you have to be careful about file locking to avoid getting the file corrupted from simultaneous updates, and--as a result--the concurrency of this approach really reeks.

[Anon]

Thanks, but I don't know how to delete older lines, that's my problem (I am a newbie).

I currently use this to add new text:

<?php
$fcontents = join ( '', file ( "chat.txt"));
$fp = fopen ("chat.txt", "w");
$newchat = StripSlashes($newchat); //stop slash being added in front of appostrophess
fwrite ($fp, "$newchat\n"); //writes new chat to file
fwrite ($fp, $fcontents); // add previous content after new content
fclose ($fp);
?>

This is working great, now what do I need to add so it only keeps, say, the first 20 lines in the text file?

Thanks
Dave

[[deleted]]

fgetcsv() seems usefull.

Using CSV you can create lines of 'comma delimited' text (can be delimited by a lot of strings)
So you can use a more database-like approach, where each line you read contains the name of the author, the date it was written, and the text itself.

If you do it like that, you can simply open the file, read and store the top 20 entries, close the file, re-open the file as a new file, and write the stored 20 lines again.