Removing A Specific Line From A File - php

Question

I have a text file like this:
1
2
3
4
5
6
7
8
9
10
And I want to remove specific lines which numbers are in an array like this:
$myfile='txt.txt';
$remove=array(1,3,6,7,10);
//wanna remove these lines
So I tried this code but It didn't work and It just doubles the text and ruins everything:
<?php
$myfile='txt.txt';
$remove=array(1,3,5,7,10);
$lines=file($myfile);
$countline=sizeof($lines);
$data=file_get_contents($myfile);
for ($i=0; $i < $countline+1; $i++) {
if (in_array($i, $remove)) {
$editeddata=str_replace($lines[$i], "", $data);
$removeline = file_put_contents($myfile, $editeddata.PHP_EOL , FILE_APPEND | LOCK_EX);
}
}
?>
I couldn't use ((for)) properly and I think it will just ruin the text because it deletes lines one after another have been deleted and it changes the order so I should have a code to remove them all at once.
And please don't give a code to just replace numbers because the main text file is not only numbers and contains word,etc...
Thanks A lot!

Answer 1

You're reading the file twice (with file and file_get_contents), which I think is confusing the later code. You have everything you need with the first call - an array of all the lines in the file. You're also using str_replace to remove the content, which seems a bit dangerous if any of the content is repeated.
I'd refactor this to simply filter the array of lines based on their line-number, then write it back to the file in a single operation:
$myfile = 'txt.txt';
$remove = [1, 3, 5, 7, 10];
// Read file into memory
$lines = file($myfile);
// Filter lines based on line number (+1 because the array is zero-indexed)
$lines = array_filter($lines, function($lineNumber) use ($remove) {
return !in_array($lineNumber + 1, $remove);
}, ARRAY_FILTER_USE_KEY);
// Re-assemble the output (the lines already have a line-break at the end)
$output = implode('', $lines);
// Write back to file
file_put_contents($myfile, $output);

Answer 2

If the file fits in memory then you can do the simple:
$myfile='txt.txt';
$remove=array(1,3,6,7,10);
file_put_contents($myfile, implode(PHP_EOL,array_diff($file($myfile,FILE_IGNORE_NEW_LINES), $remove)));
Note: Because it's a bit ambiguous whether $remove has the content or the lines you want to remove, the above code removes the content . If you want to remove lines change array_diff($file($myfile,FILE_IGNORE_NEW_LINES), $remove) to array_diff_keys($file($myfile,FILE_IGNORE_NEW_LINES), array_flip($remove))
If your file is large then you need to resort to some sort of streaming. I suggest against reading and writing to the same file and doing something like:
$myfile='txt.txt';
$remove=array(1,3,6,7,10);
$h = fopen($myfile,"r");
$tmp = fopen($myfile.".tmp", "w");
while (($line = fgets($h)) !== false) {
if (!in_array(rtrim($line, PHP_EOL), $remove)) {
fwrite($tmp, $line);
}
}
fclose($h);
fclose($tmp);
unlink($myfile);
rename($myfile.".tmp", $myfile);