如何在默认值中使用数学表达式？

Question

Why doesn't the following work in PHP?

const DAYS = 60*24*3;

I get the following error.

Parse error: syntax error, unexpected T_CONST on line 1

I'm also not able to assign an expression to the value of a property array. Note, I'm only using constant values (not calling functions or anything like that).

class A
{
    public $value = array('days'=>60*24*3);
}

The above doesn't work.

$value = array('days'=>60*24*3);

But that works fine if it's assigned to a local variable!

How do you use math expressions when assigning values?

Answer 1

Constants are defined using the define() function. const is a reserved word inside classes (and is not possible to be used outside the class scope until PHP 5.3). Therefore:

define('DAYS', 60*24*3);

will work fine.