deleting lines in file

[Anon]

I'm creating a simple chat room and my problem is I don't know how to remove lines in a file while keeping some of the rest.

After the file reaches 20 lines, the older lines start to be removed, and only the new lines are kept.

So the chat will always have 20 lines once it reaches it.

Can someone help me on how to do this.

here is what i have so far...

// Count total messages
$msgfile = "/path/to/file.txt";
$lines = file($msgfile);
$length = "count($lines)";

$total_length = "20";

if($length > $total_length) {
// remove lines
}

[Anon]

Here's how I'd do it:

// Count total messages
$msgfile = "/path/to/file.txt";
$lines = file($msgfile);
$length = count($lines); // don't use dbl-quotes here

$total_length = 20; // don't need them here either

while($total_length < count($lines)) //while loops are almost always a better way to go
{
array_pop($lines);
}

[Anon]

heh, actually this line is useless, ignore it:

$length = count($lines); // don't use dbl-quotes here

[Anon]

// Count total messages
$msgfile = "/path/to/file.txt";
$lines = file($msgfile);
$length = count($lines);

$total_length = 20;

while($total_length < $length) {
array_pop($lines);
}

how will array_pop($lines);
remove the older lines in the file.txt ?

basically the file.txt contains a line of text that prints out when my other script is called.

newer lines are at the bottom, how can i delete the older ones on the top of the file and still print the newer 20 messages?

[Anon]

my mistake, use array_shift(), not array_pop() to remove the older lines.

Does this answer your ?

[Anon]

Do you eventually re-write your text file? You should read it, print the last 20 lines, then rewrite the last 20 lines..otherwise your file will just keep growing, right?

---John Holmes...