Undesired new lines added to text document when writing to it - php

Question

I was just trying to do a simple sorting algorithm on a matrix that I read from a matrix.txt file and append the sorted matrix back to the file.
The problem is that undesired new lines are written to the text file. I also tried in parallel to echo the same things I am writing in the text file, but the echo prints everything okay.
// .. reading the file and sorting the matrix ..
// Write the sorted matrix back to the text file
$handle = #fopen("matrix.txt", "a");
if ($handle) {
fwrite($handle, PHP_EOL . PHP_EOL . "Sorted matrix:" . PHP_EOL);
for ($i = 0; $i < $n; $i++) {
for ($j = 0; $j < $m; $j++) {
echo $matrix[$i][$j] . " ";
fwrite($handle, $matrix[$i][$j] . " ");
}
fwrite($handle, PHP_EOL);
echo "<br>";
}
fclose($handle);
}
matrix.txt file contents:
1 2 5 2 5 8 12 323 1 4
8 32 2 1 3 82 2 8 4 2
1 2 5 2 5 8 12 323 1 4
8 32 2 1 3 82 2 8 4 2
In the web browser it echoes the matrix nicely sorted, each row by itself; however, in the text file, the following is appended:
Matrix sorted using selection sort:
1 1 2 2 4
5 5 8 12 323
1 2 2 2
3 4 8 8 32 82
1 1 2 2 4
5 5 8 12 323
1 2 2 2 3 4 8 8 32 82
Any clues what could cause this? Thanks in advance !

Answer 1

The problem isn't in the code you posted; it's in the input matrix you provided. Notice that every extra newline corresponds to the item which used to be at the end of the row, except for the last row. That's because the final newline from each row is being included when you read the line, and explode (which I imagine you're using) doesn't know to remove it. You could simply trim the lines before exploding to fix this, or specifically remove \r and \n characters.