New OOP php question

[dannyman1234]

Hi,

 

Im just starting out with OOP in php and I am doing the basic tutorial in: http://www.killerphp.com/tutorials/object-oriented-php. Nice tut btw!!

 

I have a question:

So I have this class:

 

class person {
       var $name;

       public $height;        
       protected $social_insurance;
       private $pinn_number;


       function __construct($persons_name) {
           $this->name = $persons_name;        
       }        

       function set_name($new_name) {
             $this->name = $new_name;
       }    

       function get_name() {        
             return $this->name;        
        }        

       private function get_pinn_number(){
           return
           $this->pinn_number;  
       }       


   }    

 

 

Then In my php page, I make the object:

 

    $stefan = new person("Stefan Mischook");   
           echo "Stefan's full name: " .  $stefan->get_name() ;  

 

What I don't understand is, How is de property $name being declared if you make the object $stefan = new person("Stefan Mischook")?

 

In other words: person is the class, but how does php know that "Stefan Mischook" is set for $name? why is "Stefan Mischook" not set for $height or $social_insurance, which are also variables inside the person class.?

 

Am I making any sense here?:/

[BeeDev]

It's to do with the function called __construct($persons_name)

 

This function always runs when you declare a new object.

 

So if you look at your __construct() function it takes in a variable $persons_name and it assigns $this->name = $persons_name;

 

So when you call :

 

$stefan = new person("Stefan Mischook");

 

it automatically assigns the given name when it runs the __construct function.

 

Hope that makes sense.

[dannyman1234]

Yes thanks, it makes sense.

 

But what about if i want to access the property "height"?

 

I tried to make a function:

 

function get_height($new_height) {

$this->height = $new_height;

return $this->height;

}

 

then in index.php

 

$stefan = new person("Stefan Mischook");

echo "Stefan's full name: " . $stefan->get_name() ;

 

echo $stefan->get_height('1.67');

 

Is this the right way to do it? I get the value printed.

 

I read in the tut about getters and setters:

 

function set_name($new_name) {

$this->name = $new_name;

return $this->name;

}

 

function get_name() {

return $this->name;

}

 

Why do we need this? function set_name already returns $this->name;.

[BeeDev]

set_name and set_height functions should not be returning values. They should return true or false in case of success of setting or failure. However, on the other hand, get_ functions should always return a value. But really it's up to you to make the decision on whether a function should set or get a value, or do both. The point is to adapt to your specific need.

[Guest WebElf]

To get your head around things you need to have a clear idea of where you are standing.

 

Set functions store data in a class.

 

Get functions retrieve stored data.

eg.

 

function get_height() {

return $this->height;

}

 

function set_height($new_height) {

$this->height = $new_height;

}

 

 

If you want to set the height when you create the person record you can redesign the constructer to accept name and height. Typically you put information a constructor that is neded to be set for all instances of a class.

 

function __construct( $persons_name, $persons_height ) {

$this->name = $persons_name;

$this->height = $persons_height;

}

 

and call it via

 

$stefan = new person( "Stefan Mischook", "1.67" );

 

then when you call get_height you will receive 1.67 back.

 

Hope this helps.