I have a simple calculator in php. And I am using the func_get_args for dynamically getting the values.

But the problem is with the multiply function.

So this is de code Calculator:

class Calculator
{
    protected $result;
    protected $operation;

    public function setOperation(OperatorInterface  $operation)
    {

        $this->operation = $operation;
    }

    public function calculate()
    {

        foreach (func_get_args() as $number) {
            $this->result = $this->operation->run($number, $this->result);
        }
    }

    public function getResult()
    {

        return $this->result;
    }
}

Multiply

class Multiply implements OperatorInterface{

    public function run($number, $result){

        return $result * $number;
    }
}

Index:

$sc = new Calculator();

$sc->setOperation(new Multiply);
$sc->calculate(10, 70);
echo $sc->getResult();

Because the result is 0. Because it starts with 0. But how to tackle this?

Thank you

interface:

interface OperatorInterface{
    public function run($number, $result);
}

If I do it like this:

class Multiply implements OperatorInterface{

    protected $result = 1;

    public function run($number, $result){    

        return var_dump($result * $number);
    }
}

and for exmample this:

$sc = new Calculator();

$sc->setOperation(new Multiply);
$sc->calculate(10, 70);
/* 
$sc->setOperation(new Adder());
$sc->calculate(100, 70);
$sc->setOperation(new Subtractor);
$sc -> calculate(500);
 */
echo $sc->getResult();

it is still 0.

CodePudding user response：

When you instantiate the calculator, result is 0. So you are multiplying 0 * $number which is always 0. You could set result to 1 in your Multiply class:

class Multiply implements OperatorInterface{
    
    protected $result = 1;

    public function run($number, $result){

        return $result * $number;
    }
}

CodePudding user response：

You are getting 0 because null * 10 give 0, after that you will get 0 * 70 which still results in 0.

Add the if statement to give a correct starting value:

class Multiply implements OperatorInterface{

    public function run($number, $result){
        
        if ($result === null) $result = 1;
        return $result * $number;
    }
}