Undefined index

[hass1980]

Hi im getting this error on my web page:

 

Notice: Undefined index: id in C:\wamp\www\chapter25\show_cat.php on line 6

 

 

 

<?php
  include ('book_sc_fns.php');
  // The shopping cart needs sessions, so start one
  session_start();

  $catid = $_GET['id'];
  $name = get_category_name($catid);

  do_html_header($name);

  // get the book info out from db
  $book_array = get_books($catid);

  display_books($book_array);


  // if logged in as admin, show add, delete book links
  if(isset($HTTP_SESSION_VARS['admin_user']))
  {
    display_button('index.php', 'continue', 'Continue Shopping');
    display_button('admin.php', 'admin-menu', 'Admin Menu');
    display_button("edit_category_form.php?catid=$catid", 
     'edit-category', 'Edit Category');
  }
  else
    display_button('index.php', 'continue-shopping', 'Continue Shopping');
  
  do_html_footer();
?>

[Maq]

You have to check to see if it exists first.

 

  $catid = isset($_GET['id']) ? $_GET['id'] : null;

[The Little Guy]

you have strict formatting on, you would have to do this:

 

if(isset($_GET['id'])){
     $catid = $_GET['id'];
}else{
     $catid = '';
}