How can errors be avoided when using functions within a class in PHP?

To avoid errors when using functions within a class in PHP, make sure to properly define the functions with the correct visibility (public, private, or protected) and use the $this keyword to refer to the current instance of the class within the function.

class MyClass {
    private $myProperty;

    public function __construct($value) {
        $this->myProperty = $value;
    }

    public function myFunction() {
        return $this->myProperty;
    }
}

$obj = new MyClass("Hello");
echo $obj->myFunction(); // Output: Hello