PHP : session variable having an undefined offset error

Question

I am a newbie in PHP programming. I am creating a simple login form with sessions. I am passing two session variables : $_SESSION['username'] and $_SESSION['logon']. Here is my code:

    $rowcount = mysqli_num_rows($result);

    if($rowcount == 1){
        session_start();
        $_SESSION['logon'] == "online";
        $_SESSION['username'] = $username;
        header("location:../index.php?username=$_SESSION[username]");

    }

The problem is that when I try to access the $_SESSION['username']variable, it gives me the appropriate value stored in it, but when I try to access the $_SESSION['logon'] variable, it gives me an undefined offset error.

'== ' this is comparision , you should assign '=' and the other thing `session_start(); `should be first line — webpic, Sep 08 '17 at 05:14

score 2 · Answer 1 · answered Sep 08 '17 at 05:12

2

$_SESSION['logon'] == "online";

is not the same as

$_SESSION['logon'] = "online";

The first is a comparision.

answered Sep 08 '17 at 05:12

yoda

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Thank you for pointing that out. My code works works now. Thank you. – Herry Potei Sep 08 '17 at 05:14

Alive to die - Anant · Accepted Answer · 2017-09-08T05:52:39.370

2

2 things:-

1.session_start(); need to be top on the each page(best to add in separate file and then include that file to every other file)

2.

$_SESSION['logon'] == "online"; //it's comparison not assignment

need to be:-

$_SESSION['logon'] = "online"; // now it's an assignment

Note:- you can get Warning: Cannot modify header information - headers ... multiple times, when you use session_start() in middle of the page.

Reference:-

1.Why setcookie( ) and session_start( ) Want to Be at the Top of the Page

2.Where exactly do I put a SESSION_START?

3.When do I have to declare session_start();?

edited Sep 08 '17 at 05:52

answered Sep 08 '17 at 05:13

Alive to die - Anant

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but shouldn't I start the session after I have verifed he is a user in my database? – Herry Potei Sep 08 '17 at 05:16
@IrfanSindhi starting session in middle of the page cause issues,Later you will get that. – Alive to die - Anant Sep 08 '17 at 05:17
Could you please elaborate how? Im kind of confused. – Herry Potei Sep 08 '17 at 05:19
@IrfanSindhi check the reference link in my answer – Alive to die - Anant Sep 08 '17 at 05:21
Thank you for the extra answer. It was really helpful. – Herry Potei Sep 08 '17 at 05:28
@IrfanSindhi glad to help you :):) – Alive to die - Anant Sep 08 '17 at 05:53

PHP : session variable having an undefined offset error

2 Answers2