Undefined index on add to array

Question

im trying to make my first class in php from an exmple

http://www.php.net/manual/en/keyword.class.php

What i have:

file cart.php

<?php
class Cart
{
  private $items; //items in our cart

  public function Cart()
  {
      $this->add_item("03", 0);
  }

  public function add_item ($artnr, $num)
  {
    $this->items[$artnr] += $num;
    echo "product added";
  }
}
?>

file index.php

    <html>
<head>
<?php
include_once('cart.php');
?>
<title>Test</title>
</head>
<body>
<?php

     $test1 = new Cart();

?>
</body>
</html>

but it crashes on the line

    this->add_item("03",0);

witht he error Undefined index: 03 in

I cant fix it, can some one help me?

The array key does not exist.

randomizer
– randomizer

2014-02-07 13:51:34 +00:00
Commented Feb 7, 2014 at 13:51 — randomizer
– randomizer, Commented Feb 7, 2014 at 13:51

John Conde · Accepted Answer · 2014-02-07 13:51:10Z

6

You need to check if that array key exists before you append to it. If it doesn't exist you need to create it first, then append to it.

  public function add_item ($artnr, $num)
  { 
    if (!isset($this->items[$artnr])) {
        $this->items[$artnr] = 0;
    }
    $this->items[$artnr] += $num;
    echo "product added";
  }

answered Feb 7, 2014 at 13:51

John Conde

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1 Comment

Sven van den Boogaart Over a year ago

Thanks it is working now, kinda weard i thought it was a official tutorial ;)

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