How do I open a file from line X to line Y in PHP?

Question

The closest I've seen in the PHP docs, is to fread() a given length, but that doesnt specify which line to start from. Any other suggestions?

Answer 1

You not going to be able to read starting from line X because lines can be of arbitrary length. So you will have to read from the start counting the number of lines read to get to line X. For example:

<?php
$f = fopen('sample.txt', 'r');
$lineNo = 0;
$startLine = 3;
$endLine = 6;
while ($line = fgets($f)) {
    $lineNo++;
    if ($lineNo >= $startLine) {
        echo $line;
    }
    if ($lineNo == $endLine) {
        break;
    }
}
fclose($f);

Answer 2

If you're looking for lines then you can't use fread because that relies on a byte offset, not the number of line breaks. You actually have to read the file to find the line breaks, so a different function is more appropriate. fgets will read the file line-by-line. Throw that in a loop and capture only the lines you want.

Answer 3

Unfortunately, in order to be able to read from line x to line y, you'd need to be able to detect line breaks... and you'd have to scan through the whole file. However, assuming you're not asking about this for performance reasons, you can get lines x to y with the following:

$x = 10; //inclusive start line
$y = 20; //inclusive end line
$lines = file('myfile.txt');
$my_important_lines = array_slice($lines, $x, $y);

See: array_slice

Answer 4

Solution from related link below question:

$file = new SplFileObject('longFile.txt');
$fileIterator = new LimitIterator($file, 1000, 2000);
foreach($fileIterator as $line) {
    echo $line, PHP_EOL;
}