属性是否默认声明为私有？ [关闭]

Question

I have the property $value which gives different error messages depending on whether I prepend private to the variable declaration or not.

Class Node{
        $value = NULL;
        public function __construct($value){
                $this->value = $value;
        }
}

$node = new Node('hello');
echo $node->value;

PHP Parse error: syntax error, unexpected T_VARIABLE, expecting T_FUNCTION in /home/ubuntu/new.php on line 4

However if I replace $value = NULL; with private $value = NULL; I get a different error message:

PHP Fatal error: Cannot access private property Node::$value in /home/ubuntu/new.php on line 11

I thought omitting the term private would automatically make the property private?

EDIT

I understand now that properties are public by default. How come I get an error when declaring the property $value without the public prepended to it?

Answer 1

You got firs error before

echo $node->value;

Put class code without calling it and you'll get same error.

You just have syntax error on line:

 $value = NULL;

Replace with:

var $value = NULL;

UPDATE

But this is wrong solution just to show where are your problem. Always set variable visibility one of:

• private
• protected
• public