name; class "/>

Implicit Property Declaration

Defining a property implicitly

$object1 = new User();
$object1->name = "Alice";
echo $object1->name;
class User {}

This code correctly outputs the string “Alice” without a problem, because PHP implicitly declares the variable $object1->name for you. But this kind of programming can lead to bugs that are infuriatingly difficult to discover, because name was declared from outside the class.
To help yourself and anyone else who will maintain your code, get into the habit of always declaring your properties explicitly within classes. Also, when you declare a property within a class, you may assign a default value to it. The value you use must be a constant and not the result of a function or expression.

Valid and invalid property declarations

class Test
public $name = "Paul Smith"; // Valid
public $age = 42; // Valid
public $time = time(); // Invalid - calls a function
public $score = $level * 2; // Invalid - uses an expression

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