How to add elements to an array that is a property of an object in PHP?
Question
I would like to be able to have an object which contains an array as a property. I would like to be able to add elements to that array. I get the errors: Warning: array_push() expects parameter 1 to be array, null given in /wwwg32Np9 on line 18 vw1997Array (I am running this in w3schools demo pages)
<!DOCTYPE html>
<html>
<body>
<?php
class Car {
public $model;
public $year;
public $passengers;
function __construct() {
$this->model = "";
$this->year = " ";
$this->passengers=array(); //?not sure if this is right
}
//wrote a function to see if I could add elements to the array this way
function addPassengers($passenger)
{
array_push($passengers, $passenger);
return $passengers;
}
}
// create an object
$herbie = new Car();
$herbie->model = "vw";
$herbie->year = "1997";
$herbie->addPassengers("Mike"); //? is this right?
// show object properties
echo $herbie->model;
echo $herbie->year;
echo $herbie->passengers; //?is this right?
?>
</body>
</html>
1 answers
solution1
1 ACCPTED 2020-04-05 07:29:25
You need to do 2 changes:
1.Use $this->passengers inside function.
2.Use print_r() to print it
<?php
class Car {
public $model;
public $year;
public $passengers;
function __construct() {
$this->model = "";
$this->year = " ";
$this->passengers=array();
}
function addPassengers($passenger)
{
array_push($this->passengers, $passenger);
return $this->passengers;
}
}
$herbie = new Car();
$herbie->model = "vw";
$herbie->year = "1997";
$herbie->addPassengers("Mike");
echo $herbie->model;
echo $herbie->year;
print_r($herbie->passengers);
?>
Output:- https://3v4l.org/aQn2h
Note:- You can write less amount of code and get the same output: https://3v4l.org/KTVAp
As other comments stated you need to use private variables instead of public
Sample example: - https://3v4l.org/8RF9j
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