Updating a File Script Issue - php

Question

I'm using this code to update a given file;
<?php
if($_POST['submit']){
$open = fopen("textfile.php","w+");
$text = $_POST['update'];
fwrite($open, $text);
fclose($open);
echo "File updated.<br />";
echo "File:<br />";
$file = file("textfile.php");
foreach($file as $text) {
echo $text."<br />";
}
}else{
$file = file("textfile.php");
echo "<form action=\"".$PHP_SELF."\" method=\"post\">";
echo "<textarea Name=\"update\" cols=\"50\" rows=\"10\">";
foreach($file as $text) {
echo $text;
}
echo "</textarea>";
echo "<input name=\"submit\" type=\"submit\" value=\"Update\" />\n
</form>";
}
?>
But somehow its showing this error:
Although the file does updated with this code when I submit my text and no error or submission, however the error its showing on the screenshot bugs me, so any way I could remove those errors?
Thanks!

Answer 1

Change line 2 to this:
if(isset($_POST['submit'])){
Change line 15 to this:
echo "<form action=\"".$_SERVER['PHP_SELF']."\" method=\"post\">";

Answer 2

Assuming that your submit button is named submit checking for $_POST['submit'] is unreliable (as not all browsers POST the submit button), you should check for another field name that is posted OR better yet, change to if($_SERVER['REQUEST_METHOD'] == 'POST'){.
Also, $PHP_SELF is assuming you have register globals on (which shouldn't be), you should use $_SERVER['PHP_SELF'] instead.

Answer 3

Joe has it. You want isset(). # (error suppression) is the coward's way out. Be a man and use isset() ;-)