PHP - How do I cut out a block of lines in a text document?

How do I cut out a chunk of text from a text file in PHP. For instance, I want to take out 开发者_运维问答lines 0-50 and turn it into a string. Maybe even put some html formatting in there. I already know what lines I need to cut out I just dont know how to select them and put them into a string.

Use file($filename). The result is an array where each element is a line from your file. Sample:

$lines = file("foo.txt");
//extract desired lines
$lines = array_slice($lines,19,21);
$string ) implode("\n",$lines);

explode on new line and output the array values from 0-50.

Open the file with fopen, read first 50 lines using fgets.

$fp = fopen('myfile.txt', 'rt');
if ($fp)
{
    for ($i = 0; $i < 50; $i++)
    {
        $s = fgets($fp);
        ...add error checking and do something with the line here
    }
}

This is efficient even if you need to read first 50 lines of a large file.

Less memory intensive approach:

$fileObject      = new SplFileObject('yourFile.txt');
$fileIterator    = new LimitIterator($fileObject, 0, 49);
$firstFiftyLines = implode(iterator_to_array($fileIterator));

or as an alternative

$fileObject      = new SplFileObject('yourFile.txt');
$fileIterator    = new LimitIterator($fileObject, 0, 49);
$firstFiftyLines = '';
foreach ($fileIterator as $currentLine) {
    $firstFiftyLines .= $currentLine;
}

If you need other lines, change the second and third argument to the LimitIterator. First one is starting offset, second iteration count (in this context lines to read).

^{Marking answer CW because question (and answer) is a duplicate of Read a file from line X to line Y?}