PHP: abstract method in interface

Question

Why can't I declare an abstract method in an interface? This is my code. Thank.

<?php
interface Connection {
    public abstract function connect();
    public function getConnection();
}

abstract class ConnectionAbstract implements Connection() {
    private $connection;

    public abstract function connect();

    public function getConnection() {
        return $this->connection;
    }
}

class MySQLConnection extends ConnectionAbstract {
    public function connect() {
        echo 'connecting ...';
    }
}

$c = new MySQLConnection();
?>

Answer 1

All functions in the interface are implicitly abstract. There is no need to use the abstract keyword when declaring a function.

Answer 2

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Answer 3

Both methods in the Connection interface are abstract. All methods in the interface are implicitly abstract. Therefore, the connect () method does not require an abstract keyword.