PHP - Private class variables giving error: undefined variable

Question

I am getting the error \"Undefined variable: interval in C:\\wamp\\www\\DGC\\classes\\DateFilter.php\"

Here is my code for the DateFilter class:

clas         


        

Answer 1

function test()
{
    echo $this->interval->format("%d days old </br>");
}

Answer 2

You have to use $this->interval to access the member variable interval in PHP. See PHP: The Basics

class DateFilter extends Filter
{
    private $interval;    // this is correct.

    public function DateFilter($daysOld)
    {
        $this->interval = new DateInterval('P'.$daysOld.'D');   // fix this
    }

    function test()
    {
        echo $this->interval->format("%d days old </br>");     // and fix this
    }
}

Answer 3

$interval is local to the function. $this->interval references your private property.

class DateFilter extends Filter
{
    //@param daysOld: how many days can be passed to be included in filter
    //Ex. If daysOld = 7, everything that is less than a week old is included
    private $interval;

    public function DateFilter($daysOld)
    {
        echo 'days old' . $daysOld .'</ br>';
        $this->interval = new DateInterval('P'.$daysOld.'D');
    }


    function test()
    {
        echo $this->interval->format("%d days old </br>");
        //echo 'bla';
    }

}

Answer 4

trying

public var $interval;

and

echo $this->interval;