[RESOLVED] Need help with math function

[LHBandit]

I've finally managed to create a function that will add all the arguments passed to it using a variable number of arguments as seen below:

function addition() 
{
	$numargs = func_num_args();
	$arg_list = func_get_args();
	for ($i = 0; $i < $numargs; $i++) {
		$result += $arg_list[$i];
	}
	return $result;
}

addition(50, 10, 5); //outputs 65
addition(1, 2); //outputs 3

The problem I'm having is doing the same thing for subtracting the arguments from one another. I've tried changing it to "$result -= $arg_list[$i];" but I always end up with a negative number.

function subtract() 
{
	$numargs = func_num_args();
	$arg_list = func_get_args();
	for ($i = 0; $i < $numargs; $i++) {
		$result -= $arg_list[$i];
		//echo $result . " ";
	}
	return $result;
}

subtract(10, 2, 3); //output is -15 but I need it to be 5

Anyone willing to help?

[madwormer2]

function subtract() 
{
	$numargs = func_num_args();
	$arg_list = func_get_args();
	for ($i = 0; $i < $numargs; $i++) {
 if($i == 0)
    $result = $arg_list[$i];
else
    $result -= $arg_list[$i];
		//echo $result . " ";
	}
	return $result;
}

[LHBandit]

Thanks, that worked like a charm!

[madwormer2]

Glad to help, mark the thread resolved please.

[laserlight]

Actually, there's no need to check for ($i == 0) on each iteration.

function subtract() {
	$num_args = func_num_args();
	$arg_list = func_get_args();
	$result = $arg_list[0]; //assume at least 1 argument passed
	for ($i = 1; $i < $num_args; $i++) {
		$result -= $arg_list[$i];
	}
	return $result;
}

EDIT:
Actually, the same mistake (not initialising $result) is made in your addition function.
It should be:

function add() {
	$num_args = func_num_args();
	$arg_list = func_get_args();
	$result = $arg_list[0]; //assume at least 1 argument passed
	for ($i = 1; $i < $num_args; $i++) {
		$result += $arg_list[$i];
	}
	return $result;
}

If you want to take into account the possibility of no arguments passed:

function add() {
	if (($num_args = func_num_args()) > 0) {
		$arg_list = func_get_args();
		$result = $arg_list[0];
		for ($i = 1; $i < $num_args; $i++) {
			$result += $arg_list[$i];
		}
		return $result;
	} else {
		return false;
	}
}

Of course, instead of returning false, you could return 0, which may be more useful.