What is the function __construct used for?
__construct
was introduced in PHP5 and it is the right way to define your, well, constructors (in PHP4 you used the name of the class for a constructor).
You are not required to define a constructor in your class, but if you wish to pass any parameters on object construction then you need one.
An example could go like this:
class Database {
protected $userName;
protected $password;
protected $dbName;
public function __construct ( $UserName, $Password, $DbName ) {
$this->userName = $UserName;
$this->password = $Password;
$this->dbName = $DbName;
}
}
// and you would use this as:
$db = new Database ( 'user_name', 'password', 'database_name' );
Everything else is explained in the PHP manual: click here
__construct()
is the method name for the constructor. The constructor is called on an object after it has been created, and is a good place to put initialisation code, etc.
class Person {
public function __construct() {
// Code called for each new Person we create
}
}
$person = new Person();
A constructor can accept parameters in the normal manner, which are passed when the object is created, e.g.
class Person {
public $name = '';
public function __construct( $name ) {
$this->name = $name;
}
}
$person = new Person( "Joe" );
echo $person->name;
Unlike some other languages (e.g. Java), PHP doesn't support overloading the constructor (that is, having multiple constructors which accept different parameters). You can achieve this effect using static methods.
Note: I retrieved this from the log of the (at time of this writing) accepted answer.