What wrong with undefined index o?

Question

I got error in my data viewing page, what is the correction for my php script

Here is my php script:

Notice: Undefined index: o in /home/tz005/public_html/COMP1687/view_data.php on line 64

<?php
        $con=mysqli_connect("mysql.cms.gre.ac.uk","tz005","punceg5L","mdb_tz005");

        if (is_numeric($_GET['o']))
        {
            $o=$_GET['o'];
        }else {
            $o=0;
            }

        if ($o >=1){
            $prev=$o-1;
            } else{
                $prev=0;
            }

Please make sure that an element named o is submited or passed with url. — AeJey, May 22 '14 at 05:50
Maybe $_GET doesn't have a value for 'o'. Use `isset($_GET['o'])` before `is_numeric`. — bozdoz, May 22 '14 at 05:50
Direct Duplicate Close option is so useful especially in PHP tag — Mr. Alien, May 22 '14 at 05:52

score 0 · Answer 1 · answered May 22 '14 at 05:51

You need to add an isset() function to check if $_GET['o'] even exists.

Read more about isset() Here

use this:

 <?php
    $con=mysqli_connect("mysql.cms.gre.ac.uk","tz005","punceg5L","mdb_tz005");

    if (isset($_GET['o'] && is_numeric($_GET['o']))
    {
        $o=$_GET['o'];
    }else {
        $o=0;
        }

    if ($o >=1){
        $prev=$o-1;
        } else{
            $prev=0;
        }

What wrong with undefined index o?

1 Answers1