I’m getting the following error:
Fatal error: Declaration of Shoppingcart::addToCart() must be compatible with that of Ishoppingcart::addToCart() in klassen.php on line 118
What could be the problem? I can’t find it script:
<?php // begin interface Ishoppingcart{ public function addToCart(); public function printOverzicht(); } abstract class Shoppingcart implements Ishoppingcart { protected $producten = array(); public function addToCart( Product $product) { $this->producten[] = $product; } } class Myshoppingcart extends Shoppingcart { public function printOverzicht(){ echo ("<table border=1> <tr> <td colspan='7'>Bestellingoverzicht</td> </tr> <tr> <td bgcolor=#cccccc> Product ID</td> <td bgcolor=#cccccc> Beschrijving</td> <td bgcolor=#cccccc> Merk</td> <td bgcolor=#cccccc> Model</td> <td bgcolor=#cccccc> Prijs</td> <td bgcolor=#cccccc> Aantal</td> <td bgcolor=#cccccc> Korting</td> </tr>"); foreach($this->producten as $product){ $rij = ""; $rij .= "<tr>"; $rij .= "<td>".$product->getID()."</td>"; $rij .= "<td>".$product->getBeschrijving()."</td>"; $rij .= "<td>".$product->getMerk()."</td>"; $rij .= "<td>".$product->getModel()."</td>"; $rij .= "<td>".$product->getPrijs()."</td>"; $rij .= "<td>".$product->getAantal()."</td>"; $rij .= "<td>".$product->getKorting()."</td>"; $rij .= "</tr>"; echo ($rij); } echo ("</table>"); } } class Product { private $id; private $beschrijving; private $merk; private $model; private $prijs; private $aantal; private $korting; function __construct($id, $merk, $model, $prijs, $aantal, $korting){ $this->id = $id; $this->beschrijving = $beschrijving; $this->merk = $merk; $this->model = $model; $this->prijs = $prijs; $this->aantal = $aantal; $this->korting = $korting; echo ("<br />Nieuw Product object $beschrijving wordt aangemaakt"); } public function __destruct(){ // voer benodigde acties uit echo ("<br />Product object $this->beschrijving wordt verwijderd"); } // set function public function setId($id){ $this->id = $id; } public function setBeschrijving($beschrijving){ $this->beschrijving = $beschrijving; } public function setMerk($merk){ $this->merk = $merk; } public function setModel($model){ $this->model = $model; } public function setPrijs($prijs){ $this->prijs = $prijs; } public function setAantal($aantal){ $this->aantal = $aantal; } public function setKorting($korting){ $this->korting = $korting; } // get function public function getId(){ return $this->id = $id; } public function getBeschrijving(){ return $this->beschrijving; } public function getMerk(){ return $this->merk; } public function getModel(){ return $this->model; } public function getPrijs(){ return $this->prijs; } public function getAantal(){ return $this->aantal; } public function getKorting(){ return $this->korting; } // printProductInfo public function printProductInfo(){ $rij = "<tr><td>$this->id</td>"; $rij .= "<td>$this->beschrijving</td>"; $rij .= "<td>$this->merk</td>"; $rij .= "<td>$this->model</td>"; $rij .= "<td>$this->prijs</td>"; $rij .= "<td>$this->aantal</td>"; $rij .= "<td>$this->korting</td>"; echo ($rij); } } // einde ?>
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Answer
Ishoppingcart::addToCart()
states that the method does not take any parameter, while the implementation Shoppingcart::addToCart(Product $product)
requires that a parameter of type Product
must be passed into the method. This means that both declarations are incompatible and while the implemented interface must be satisfied PHP throws the shown error.
Solution would be to either change Ishoppingcart::addToCart()
to Ishoppingcart::addToCart(Product $product)
so that it requires a parameter of type Product
or to change Shoppingcart::addToCart(Product $product)
to allow no parameter to passed into the method: Shoppingcart::addToCart(Product $product = null)
;
The correct way depends on your application requirements.