How to fix 'Notice: Undefined index:' in PHP form action

forms, php, post

Solution

`Assuming` you only copy/pasted the relevant code and your form includes `<form method="POST">`

if(isset($_POST['filename'])){
    $filename = $_POST['filename'];
}
if(isset($filename)){ 
    echo $filename;
}

If `_POST` is not set the `filename` variable won't be either in the above example.

An alternative way:

$filename = false;
if(isset($_POST['filename'])){
    $filename = $_POST['filename'];
 } 
    echo $filename; //guarenteed to be set so isset not needed

In this example filename is set regardless of the situation with `_POST`. This should demonstrate the use of `isset` nicely.

More information here: http://php.net/manual/en/function.isset.php

Problem

I received the following error message when I tried to submit the content to my form. How may I fix it? Notice: Undefined index: filename in D:\wamp\www\update.php on line 4 Example Update.php code: ``` <?php $index = 1; $filename = $_POST['filename']; echo $filename; ?> ``` And $_POST['filename'] comes from another page: ``` <?php $db = substr($string[0],14) . "_" . substr($string[1],14) . "_db.txt"; ?> <input type="hidden" name="filename" value="<?php echo $db; ?>"> ```

Original source