Undefined index in PHP [duplicate]

Question

Possible Duplicate:
PHP: “Notice: Undefined variable” and “Notice: Undefined index”

Good day!

I am having the following error in my code:

<?php
if (!$_POST['SUBMIT']){   //ERROR: Undefined index
?>
    <H2>Add Employee</H2>
    <form action="<?php print $_SERVER['PHP_SELF']; ?>" method="POST">
    <table width="400" border="0" cellspacing="1" cellpadding="2">
       <tr>
            <td width="100">SSN</td>
            <td><input name="SSN" type="text" id="SSN"></td>
       </tr>
       <tr>
            <td width="100">&nbsp;</td>
            <td><input name="SUBMIT" type="SUBMIT" id="ADD" value="ADD"></td>
       </tr>
    </table>
    </form>
 <?php
    }
    else {
    //code here
    }
?>

How can I remove the error above? Thank you.

try and do a print_r($_POST) or var_dump($_POST) and see what's in the array first — KJYe.Name
– KJYe.Name, Commented Apr 15, 2011 at 12:48

gmhk · Accepted Answer · 2014-02-27 07:56:26Z

15

It should be a notice and not an error.

To fix is you'll have to check whether $_POST['submit'] is set:

if(!isset($_POST['submit'])) {
    ...
}

edited Feb 27, 2014 at 7:56

gmhk

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answered Apr 15, 2011 at 12:50

halfdan

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Comments

Tanner Ottinger · Accepted Answer · 2011-04-15 12:51:34Z

It's where you test to see that is isn't there. It should be !isset($_POST['SUBMIT']). This is because the index, SUBMIT, won't be set, thus won't have a value such as true to pass the if(...). isset() checks to see if the index/variable is actually set.

Try this:

<?php
    if (!isset($_POST['SUBMIT'])){   //ERROR: Undefined index
?>
<H2>Add Employee</H2>
<form action="<?php print $_SERVER['PHP_SELF']; ?>" method="POST">
<table width="400" border="0" cellspacing="1" cellpadding="2">
   <tr>
        <td width="100">SSN</td>
        <td><input name="SSN" type="text" id="SSN"></td>
   </tr>
   <tr>
        <td width="100">&nbsp;</td>
        <td><input name="SUBMIT" type="SUBMIT" id="ADD" value="ADD"></td>
   </tr>
</table>
</form>
<?php
    }
    else {
    //code here
    }
?>

Florian · Accepted Answer · 2011-04-15 12:51:06Z

4

<?php
  if (!isset($_POST['SUBMIT'])){   //ERROR: Undefined index
?>

This tests, if the index is set

answered Apr 15, 2011 at 12:51

Florian

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Comments

Spudley · Accepted Answer · 2011-04-15 12:53:32Z

3

Options:

Disable warning messages, by editing the setting in PHP.ini
Add an @ sign in front of the variable name, which will suppress the error on that particular line.
Change your code to use isset($_POST['SUBMIT']) before checking it further.

Of these, the third option is definitely the best. You shouldn't assume that any variable supplied by the user will be set as you expect; you should always check that it's set at all, and also that it's set to the expected values. Otherwise you are liable to be open to hacking attacks.

answered Apr 15, 2011 at 12:53

Spudley

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2 Comments

Ollie Saunders Over a year ago

The first two bullet points you suggest are bad practice and I wouldn’t recommend. The only time you want to disable warnings are when you run on production. Never use @, ever. There’s always a better alternative.

Spudley Over a year ago

@Ollie - Granted I stated that the options are available, but I didn't recommend them; I explicitly stated that the isset() option was the one to go for.

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