无法将值存储到类中的变量

Question

I'm trying to store the value from the class below as a variable, so i could used it later on, but I can't get it working.

Any ideas?

class Dates {


    public function __construct($date) {
    $this->DateCompare($date);
    }
    public function DateCompare($date) {
        $date1 = new DateTime("2015-04-08");
        $date2 = new DateTime($date);
        $diff=date_diff($date1,$date2);
        return $diff->format("%a");

    }
}

echo $test = new Dates("2015-05-04");

Error I'm getting: Catchable fatal error: Object of class Dates could not be converted to string in /virtual/index.php

As said before, I don't want to echo that out, just store it in the $test variable, but if I can't even echo that out, then I'm not storing it either.

Answer 1

The only thing a class constructor can return [directly or indirectly] is itself.

public static function instance() { return new self(); }

Add the above line and then get rid of the constructor. Replace the echo call with:

$test = Dates::instance() -> DateCompare("2015-05-04");

echo $test;

Explanation: your initial code, was trying to echo an instance of the Dates Object, the return you had was ignored because a new Class ALWAYS HAS TO Return ITSELF Actually the return you had got dumped, since it was returned back to the constructor but didn't go anywhere from there.

An alternative, if you were planning to Echo it; would be to add a __tostring() function which would get triggered when you try to echo the Class Instance Object.