Class not printing variable

Question

Im trying to understand objects & classes. But Im having a problem. Im trying to pass a variable from a class into another class.

Why Im doing this is mostly because I want to understand more how classs work but also for future where Im gonna need to send database connection into classes.

Here is my code simplified for the problem:

class databaseConnection
{
    public function connect(){

        return "localhost";

    }
}

class like
{

    private $database;

    public function __construct(){

        $this->database = databaseConnection::connect();

    }

    public function addLike()
    {
        return $database;
    }
}

$obj = new like;
echo $obj->addLike();

But this doesn't show anything. What i thought the results would be is echo "localhost";

Why isn't this working?

You should turn up error reporting, this would have helped.

deceze
– deceze ♦

2014-03-17 08:41:56 +00:00
Commented Mar 17, 2014 at 8:41 — deceze
– deceze ♦, Commented Mar 17, 2014 at 8:41

xdazz · Accepted Answer · 2014-03-17 08:39:20Z

1

connect is not a static method, you should either change it to static or create an instance.

// if you use databaseConnection::connect();
public static function connect(){

or

$db = new databaseConnection;
$this->database = $db->connect();

And you also need to change

public function addLike()
{ 
    // use $this to access object property
    return $this->database;
}

answered Mar 17, 2014 at 8:39

xdazz

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Comments

hsz · Accepted Answer · 2014-03-17 08:38:01Z

1

You are calling databaseConnection::connect() as a static method. Modify it to:

public static function connect(){ }

Edit - as @Shankar Damodaran pointed, also add:

public function addLike()
{
    return $this->database;
}

answered Mar 17, 2014 at 8:38

hsz

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3 Comments

Jacob Over a year ago

Tried changing that but it still wont output anything

Shankar Narayana Damodaran Over a year ago

You need to make use of return $this->database; on your addLike()

hsz Over a year ago

Oh, your're right @ShankarDamodaran. I have missed it. :(

Community · Accepted Answer · 2017-05-23 11:49:47Z

First of all you should really follow convention and start naming classes StartingWithCapitalLetter.

Secondly, "::" operator is used to call static methods (to put it simply - you don't have to create object of a class to call them, if they are public).

Normally, to call object's method you use operator "->", like $object->method(arguments); So in your case, you need to first create an object of your databaseConnection class (because you can't call methods on not-initialized methods) and then call "connect" on it, like that:

$connection = new databaseConnection();
$database = $connection->connect();

To pass a parameter, you need to modify the method declaration

public function connect($parameter){
    return "Connecting to " ... $parameter;
}

and call it with

$database = $connection->connect($parameter);

On a sidenote, you should really use parenthesis when creating objects of a class, like:

$obj = new like();
echo $obj->addLike();

Also, as deceze pointed out, you need to access class variable using $this instead of accessing local method variable:

public function addLike()
{
    return $this->database;
}

u_mulder · Accepted Answer · 2014-03-17 08:39:45Z

0

public function addLike()
{
    return $this->database;
}

answered Mar 17, 2014 at 8:39

u_mulder

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Comments

deceze · Accepted Answer · 2014-03-17 08:40:58Z

0

$database and $this->database are two different variables. $database is a local function variable which does not exist, it's not the object property you set before.

answered Mar 17, 2014 at 8:40

deceze♦

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