Php replace line in a file txt

Question

<?php
$myFile = "/home/user1/www/cgi-bin/mytext.txt";
$lines = file($myFile);
$lines[3] = $_POST['title'];
file_put_contents($myFile , implode("\n", $lines));
?>

I would change only the row "number 3" without changing the other rows, where mistake?

i have input mytext.txt:

• line1 -------------------------------------
• line2 #WORD:
• line3 CHANGETHIS
• line4
• line5 HELLO
• line6 PIPPO
• line7 FOO
• line8 KATEEOWEN

after lunch script this is the ouput mytext.txt:

• line1 -------------------------------------
• line2
• line3 #WORD:
• line4
• line5 CHANGETHIS
• line6
• line7 $_POST['title']
• line8 HELLO
• line9
• line10 PIPPO
• line11
• line12 FOO
• line13
• line14 KATEEOWEN

Answer 1

You can either use the FILE_IGNORE_NEW_LINES constant in file() or don't use more newlines:

file_put_contents($myFile , implode('', $lines));

Or just this as it will be imploded for you:

file_put_contents($myFile , $lines);

But you'll need to add a newline here:

$lines[3] = $_POST['title'] . "\n";

So this might be the most straight forward:

$lines = file($myFile, FILE_IGNORE_NEW_LINES);
$lines[3] = $_POST['title'];
file_put_contents($myFile , implode("\n", $lines));