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PHP Build a Basic PHP Website (2018) Listing and Sorting Inventory Items Working with Functions

Seth Johnson
Seth Johnson
15,199 Points

I've hit the wall of incomprehension.

Okay, I seriously need help here. I plugged the code in for this portion of the quiz to my own local machine, and so got the correct answer. BUT.

I absolutely have no [expletive deleted] idea HOW or WHY.

I took things as incrementally as I feel like I possibly could have, and even went so far as to var_dump everything and make notes to myself so I could figure out what was (or wasn't) happening. Like so:


$numbers = array(1,2,3,4);
$total = count($numbers);
$sum = 0;
$loop = 0;

foreach($numbers as $number) {
    $loop = $loop + 1;
    if ($loop < $total) {
        $sum = $sum + $number;

echo " <--- this one is 'number'" . "</br>";
echo " <--- this one is 'loop'" . "</br>";
var_dump($loop + 1);
echo " <--- this one is 'loop plus one'" . "</br>";
echo " <--- this one is 'total'" . "</br>";
echo " <--- this one is 'sum'" . "</br>";
var_dump($sum + $total);
echo " <--- this one is 'sum plus total.' Allegedly." . "</br>";
//echo $sum;

And it all checks out, and got all of this as my output:

  • int(4) <--- this one is 'number'
  • int(4) <--- this one is 'loop'
  • int(5) <--- this one is 'loop plus one'
  • int(4) <--- this one is 'total'
  • int(6) <--- this one is 'sum'
  • int(10) <--- this one is 'sum plus total.' Allegedly.

I'm certainly no mathemagician, but if my basic arithmetic is correct, "$sum" starts out as 0, and remains at 0 once the loop runs...and $number is 4 once the loop runs...so...how do the laws of time and space bend so that 0 + 4 = 6?!? (Since, y'know, that's presumably what the "$sum" + "$number" adds up to for the "correct" answer.) My brain is melting. Please advise. Thanks very much in advance.

1 Answer

Steven Parker
Steven Parker
229,920 Points

The second part of your premise "$sum ... remains at 0 once the loop runs" is incorrect because of this line:

        $sum = $sum + $number;

Each time through the loop, $sum gets bigger:

  • when $number is 1, $sum becomes 1 (0 + 1)
  • when $number is 2, $sum becomes 3 (1 + 2)
  • when $number is 3, $sum becomes 6 (3 + 3)
  • when $number is 4, nothing happens since 6 is not less than 4 ($total)

So when the loop finishes, $sum is 6and the laws of time and space remain intact. :dizzy: :wink:

Seth Johnson
Seth Johnson
15,199 Points

Somewhere off in the distance, you may hear something resembling the most tumultuous thunderstorm that ever was or ever will be...but it is, in fact, only the sound of my palm hitting my forehead, upon figuring out the situation with this loop. Thank you @Steven. :)

Steven Parker
Steven Parker
229,920 Points

Glad I could help, and happy coding! :hear_no_evil: