Undefined index error in PHP

Question

I get the following error message:

Undefined index: log in C:\wamp\www\Networking Script\home.php on line 20

When using the following PHP code:

<?php
  include("session/DBConnection.php");
   $user = $_SESSION['log']['username'];  //this is the 20th line in home.php
    $query = mysql_query("SELECT * FROM members WHERE username = '$user'")or die (mysql_error()); 
    $display = mysql_fetch_array($query);   ?>

Please Help me Guys :) Thank you :)

`$_SESSION['log']` doesn't exist, did you forget to start the session? — Musa, Jun 23 '13 at 16:37

score 2 · Answer 1 · answered Jun 23 '13 at 16:39

2

Start your script with

session_start();

answered Jun 23 '13 at 16:39

Wouter Dorgelo

11,770
11
62
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score 1 · Answer 2 · answered Jun 23 '13 at 16:42

1

Undefined index is probably a "notice". Just means that you are trying to access a part of the array that hasn't been initialized first.

you can use array_key_exists before you read from the array to check if the offset exists first

answered Jun 23 '13 at 16:42

Marc

416
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8

A session had already been started - ignoring session_start() I am getting this error. – Lalith Jun 23 '13 at 16:51

score 0 · Answer 3 · answered Jun 23 '13 at 16:41

0

It is also possible that you have just forgotten to start your session. Remember, you also have to use this function to resume a session: PHP: session_start - Manual

answered Jun 23 '13 at 16:41

Eastborn

73
1
5

score 0 · Answer 4 · answered Jun 23 '13 at 16:41

0

You need to invoke session_start at beginning of each file where session data is accessed.

answered Jun 23 '13 at 16:41

Rubin Porwal

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1
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amigura · Answer 5 · 2013-06-23T16:55:35.463

it just tell you that variable on line 20 does not exist yet.

session_start();

if(isset($_SESSION['log']['username'])
{

include("session/DBConnection.php");
        $user = $_SESSION['log']['username'];  
        $query = mysql_query("SELECT * FROM members WHERE username = '".mysql_real_escape_string($user)."'")or die (mysql_error()); 
        $display = mysql_fetch_array($query); 
{
else
{
// on username
}

http://www.php.net/manual/en/book.pdo.php

http://uk1.php.net/manual/en/mysqlinfo.api.choosing.php

http://php.net/manual/en/function.htmlspecialchars.php output code to browser

http://php.net/manual/en/function.mysql-real-escape-string.php

score 0 · Answer 6 · answered Jun 23 '13 at 17:34

Pretty sure it's been said, but at the risk of being rude......It means that vairable has not been set. It's empty. session_start(); Would be the first thing to check. If it doesn't get through your "if isset" piece this value won't be set. Try simply printing out the variable after it's allegedly been set, also check the variable BEFORE it gets sent anywhere.

Undefined index error in PHP

6 Answers6