Basic fileread question in PHP / - php

Question

I have a 12 XML files from which I am extracting ONE CSV file, from which - I am extracting column 1 and appending values to a tt.txt file .
NOW, I need to extract the values from this .txt file... everytime data is written to it ...
But the problem is , when I use
$contents = fread ($fd,filesize ($filename));
fclose ($fd);
$delimiter = ',' ;
$splitcontents = explode($delimiter, $contents);
IT reads ONLY from the first value of the file , every time a tt.txt file is appended !
I hope u understand the problem .. What I need is , I want $contents to have only the new data that was appended... instead it reads from the start of the file everytime...
Is there a way to achieve this, or does php fail ?/
This prob is extraction from TXT file- > performing computations- > writing INTO a new txt file . The problem being that I can't read from a middle value to a new value.. PHP always reads from the start of a file.

Answer 1

I think you need to store the last file position.
Call filesize to get current length, read the file, later, check if filesize is different (or maybe you know this some other way, and use fseek to move the cursor in the file, then read from there.
IE:
$previousLength = 0;
// your loop when you're calling your new read function
$length = filesize($filename);
fseek($fd,$previousLength);
$contents = fread($fd,$length - $previousLength);
$previousLength = $length;

Answer 2

It is only reading the first field because PHP does not automatically assume that a newline character (\n) means a new record; you have to handle this, yourself.
Using what you already have, I would do the following:
$contents = fread($fd, filesize($filename));
close($fd);
/* Now, split up $contents by newline, turning this into an array, where each element
* is, in effect, a new line in the CSV file. */
$contents = explode("\n", $contents);
/* Now, explode each element in the array, into itself. */
foreach ($contents as &$c) {
$c = explode(",", $c);
}
In the future, if you want to go line-by-line, as you run the risk of hogging too many resources by reading the entire file in, use fgets().

Answer 3

I'm not great at arrays but it sounds to me like you need an associative array (I'm doing a similar thing with the following code.
$lines = explode("\n", $contents);
foreach ($lines as $line) {
$parts = explode(',', $line);
if (count($parts) > 0) {
$posts = array();
$posts[] = array('name' => $parts[3],'email' => $parts[4],'phone' => $parts[5],'link' => $parts[6],'month' => $parts[0],'day' => $parts[1],'year' => $parts[2]); }
foreach ($posts as $post):
$post = array_filter(array_map('trim', $post));