read through file backwards?

Anon

i want to read through a file line by line but starting at the end of file.

i need it to analize each line and preg_patch it.. if the line matches , then i want it to print.

i need it to successfully match 20 lines (which could be many more lines because of the ones that don't match)

is there any way to do this check line by line?

van__

well,
as I said before, you probably want to do a preg_match_all for optimum performance.

but, since you want line by line...

// exec the code I handed you before.

// here you file() away
$lines = file($last);

for ($i=count($lines);$i>0;$i--) {
if (preg_match('/^{(expression)$/is',$lines[$i-1]))} {
//do something...
}
}

Anon

Read the entire file into an array with file(), and then loop through the array in reverse order.

Text files aren't random access, because genreally there's no way to predict where the line breaks are without actually reading the file.

Anon

thanks again Van, now you have written the whole script basically =) i am learning.

-mike

mmilano

thanks grumbler, i probably shoulda mentioned as van knew from yesterday.. i don't really want to put the entire log into an array because the logs are too big. thanks for your time!

Anon

after looking at the script and your post again, i'm realizing we are bringing everyline into an array..

i just checked out php.net for the preg_match_all function and i'm going to give that method a try.

it looks like i'll bring the entire file into a variable and the run the preg_match_all ..

thanks again, the light bulb just switched on.

Anon

Hmm, an idle thought: Are you on a Linux/Unix-ish system? If that's the case, maybe a system call like $twenty_lines = tail -n20 filename.log; will be available to get you what you want.

van__

ahh the realization of potentially having to loop through hundreds of lines has settled in. 🙂

Ya, fopen() instead and use preg_match_all to make your array in one pass... makes a nice and speedy page.