php - add to end of a string and save to txt file - php

Question

OK guys, this is my first post. I have searched all over and spent countless hours and I am still stuck so I asking for help with this relatively easy PHP module.
basically in a nutshell, what I want to do is upload a text file into an uploads directory, and have PHP process the file and perform a string function that will add HTML BREAK TAGS to the end of each line and then save this output to file. I have learned how to echo the formatted text into the browser and it appears the way it should as formatted html, but it doesn't work to write back to the file.
here is the code;
<?php
$form = <<<EOD
<form enctype="multipart/form-data" action="" method="POST">
<input type="hidden" name="MAX_FILE_SIZE" value="100000000" />
Choose an file to upload: <input name="uploadedfile" type="file" /><br />
<input type="submit" value="Upload File" />
</form>
EOD;
echo $form;
$target_path = "uploads/"; //SETS THE UPLOAD DIRECTORY
$target_path = $target_path . basename( $_FILES['uploadedfile']['name']); // GETS FILEPATH OF UPLOAD FOR OPENING/PROCESSING
$uploadfile = basename($_FILES['uploadedfile']['name']); //GETS FILENAME OF THE UPLOADED FILE IN CASE ITS NEEDED.
//PROCESSING - MOVES TMP FILE INTO TARGET DIRECTORY. NEED STRING FUNCTIONS APPLIED TO ADD <BR/> AT END OF EACH LINE.
if(move_uploaded_file($_FILES['uploadedfile']['tmp_name'], $target_path)) {
$file = fopen($target_path, "r");
while(!feof($file))
{
$line = fgets($file); //READS EACH LINE
// STRING PROCESSING PART -- SHOULD I USE str_replace, substr_replace, nl2br, or str_pad ??
..........CODE GOES HERE............PLEASE HELP ME CHOOSE THE RIGHT CODING HERE...THANKS!!! SORRY FOR THE PSEUDOCODE!
/* EXAMPLE SCRIPT:
$line2 = str_replace("\n", "<br />\n", $line);
// THIS WORKS -- GREAT FOR OUTPUTTING FORMATTED HTML INTO BROWSER
echo $line2;
// FOR NICE VIEWING BUT STILL CANNOT GET FORMATTED
// HTML TO SAVE TO FILE USING FWRITE() ...
*/
fwrite($file, $newstr);
} //CLOSES WHILE
fclose($file); //CLOSES FILE HANDLE
} //CLOSES IF
?>
too many late nights, open windows, and troubleshooting steps to make my brain want to explode! When I know one of you guys can knock this out in 2 minutes!!!
I notice I keep getting this error log:
PHP Warning: Module 'mailparse' already loaded in Unknown on line 0

Answer 1

There are a couple of problems with what you're doing currently. First, you've opened the file for reading only, but even if you change that, you won't be able to just replace a line with a longer line in the same file. In order for your current approach to work, you'll need to open a second file for writing, and add the modified lines into the second file as you go. But as long as the files aren't very large, you should be able to create the modified file more simply:
file_put_contents($output_file, nl2br(file_get_contents($input_file)));
Incidentally, the mailparse warning does not appear to be related to the code you've posted here.