OOP Type hinting

Warning: foreach() argument must be of type array|object, string given in C:\xampp\htdocs\OOPtutorial\index.php on line 56

Code:

public function sanitize($data){

foreach($data as $key =>$value){
$data[$key] = addslashes($value);
//adds slashes to the data and puts it to the same space to sanitize this data
}
$this->data = $data;
return $this;
}

FIX: at the argument of the function sanitize, add array as typehinting so we can only expect arrays

public function sanitize(array $data){…

Fatal error: Uncaught TypeError: Signup::sanitize(): Argument #1 ($data) must be of type array, string given, called in C:\xampp\htdocs\OOPtutorial\index.php on line 90 and defined in C:\xampp\htdocs\OOPtutorial\index.php:54 Stack trace: #0 C:\xampp\htdocs\OOPtutorial\index.php(90): Signup->sanitize(”) #1 {main} thrown in C:\xampp\htdocs\OOPtutorial\index.php on line 54

Problem : at sanitize call the data passed must be an array

$data = ‘ ‘; //data

$myClass->sanitize($data)->create(‘my-data.json’)->save();

in this case sanitize($data) is getting a string

Fix:

$data = $_POST;

$myClass->sanitize($data)->create(‘my-data.json’)->save();

//now the function recieves an array as expected

//type hinting in arrays:

Fatal error: Uncaught TypeError: stuff(): Argument #1 ($data) must be of type car, string given, called in C:

function stuff(car $data){
var_dump($data);
}

stuff(“something”);

in this case, function stuff expects an object of type car but receives a string

error: Uncaught TypeError: stuff(): Argument #1 ($data) must be of type car, bike given,

function stuff(car $data){
echo $data->range(20);
}

$bike = new bike();

stuff($bike);

in this case the function expects a parameter of type car, but it was given a parameter of type bike

Fix:

in this case we can use an interface that can be extended by all classes and change the type to that interface

interface Vehicle{
public function range(float $miles);
}

function stuff(vehicle $data){
echo $data->range(20) . “<br>”;
}