Understanding PHP Class OOP structure [closed] - php

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I'm trying to create a class function but somehow it won’t work and I can’t figure out what’s the problem. Is it the way I declare the variable or what so ever?
<?php
class Car{
var $model;
var $make;
var $speed;
function Car ( $model, $make, $speed)
{
$this->model = $model;
$this->make = $make;
$this->speed = $speed;
}
function accelerate ($speed)
{
$add = 5;
$speed = $speed + $add;
return $speed;
}
function get_status()
{
echo "Car status : \n";
echo "Model :" $this-> model "\n";
echo "Make :" $this-> make "\n\n";
}
function get_speed()
{
return $this->speed;
}
}
?>
<?php
$car1 = new Car();
$car1 -> get_status("Vios", "Toyota");
for( $i = 0; $i < 5 ; $i++)
{
echo "Accelerating... <br> \n";
echo "Current speed : accelerate(5) km/h <br>";
}
?>

Answer 1

Lots of issues with your code. But at least this cleaned up version should work without the script dying completely. Here is a breakdown of what I did:
Set the variables that were set as var to public since that is the preferred method of setting variables.
In function Car, I set default values for $model, $make & $speed so if they are not passed—like in your example—there is at least a default value to act on.
Your echo lines in get_status did not have the . for concatenation so they were not properly concatenating the strings.
Then you setting $this-> make and $this-> model with empty spaces is syntactically incorrect. So set those to $this->make and $this->model.
Then when you are calling the class, you set this "Current speed : accelerate(5) km/h <br>"; which is syntactically incorrect as well. So set that to echo "Current speed : " . $car1->accelerate(5) . " km/h <br>"; so it can actually echo values.
But that said, unclear on what the output is for this code. The logic is a bit of a mess. But at least it’s not completely dying like it did before!
And here is the cleaned up code:
class Car {
public $model;
public $make;
public $speed;
function Car ($model = 0, $make = 0, $speed = 0) {
$this->model = $model;
$this->make = $make;
$this->speed = $speed;
}
function accelerate ($speed) {
$add = 5;
$speed = $speed + $add;
return $speed;
}
function get_status () {
echo "Car status : \n";
echo "Model :" . $this->model . "\n";
echo "Make :" . $this->make . "\n\n";
}
function get_speed () {
return $this->speed;
}
}
$car1 = new Car();
$car1->get_status("Vios", "Toyota");
for( $i = 0; $i < 5 ; $i++) {
echo "Accelerating... <br> \n";
echo "Current speed : " . $car1->accelerate(5) . " km/h <br>";
}
And—like I said before—since the way you are calling the class makes little sense to the structure you have, I slightly reworked the code above so it loops through an array of car values like this:
$car_array = array("Vios", "Toyota");
foreach ($car_array as $car_value) {
$car1 = new Car($car_value);
$car1->get_status();
for( $i = 0; $i < 5 ; $i++) {
echo "Accelerating... <br> \n";
echo "Current speed : " . $car1->accelerate(5) . " km/h <br>";
}
}

Answer 2

Add a constructor like this:
public function __construct($model = 0, $make = 0, $speed = 0) {
$this->model = $model;
$this->make = $make;
$this->speed = $speed;
}
http://us3.php.net/manual/en/language.oop5.decon.php

Answer 3

When concatenating strings, you must use the dot operator:
echo "abcd" . "efgh";