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PHP Build a Simple PHP Application Working With Functions Working with Functions

Stephen Printup
Stephen Printup
UX Design Techdegree Student 45,252 Points

Stage 6, Working with functions: Confused


I've passed the quiz, but I'm not sure how this works. Could someone please explain it to me?


$numbers = array(1,2,3,4);

$total = count($numbers);

$sum = 0;

$output = "";

$i = 0;

foreach($numbers as $number) {

    $i = $i + 1;

    if ($i < $total) {

        $sum = $sum + $number;



echo $sum;


The options are: A-1234 B-4321 C-321 D-6

Hi Stephen,

Fixed markdown to show syntax highlighting. While you had the triple backticks, it was missing the php language specifier.

2 Answers

Hi Stephen,

The easiest way to work through these types of problems is with a sheet of paper, or text editor, to keep track of the values of variables through each iteration of the loop.

The short answer is that i gets incremented before it's checked against the length of the array. So, by the start of the 4th iteration of the loop, i == 4 and the if statement evaluates to false. Therefore, the only numbers that got added from the array are 1, 2, and 3.

Hope this helps!

Think of $total as just the number 4, and i starts at 0.

Loop iteration 1:
  i += 1
  i == 1
  i < 4 // True
    add current number (1) to sum (0)
    sum == 1

Loop iteration 2:
  i += 1
  i == 2
  i < 4 // True
    add current number (2) to sum (1)
    sum == 3

Loop iteration 3:
  i += 1
  i == 3
  i < 4 // True
    add current number (3) to sum (3)
    sum == 6

Loop iteration 4:
  i += 1
  i == 4
  i < 4 // False
    // sum remains at 6