Why is the answer of $sum 6? - php

Question

<?php
$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;
?>
I'm going through PHP on TeamTreehouse.com, whilst learning php this was one of the quiz question, the answer is 6. I don't know why the answer is 6, can someone explain?

Answer 1

The variable $i is initialized by 0 (zero).
Before the condition if ($i < $total) is tested $i is incremented by 1. So even the first time it equals 1.
In the third pass $i equals 3, and in the fourth pass it equals 4 which is NOT < $total.
Therefore only 3 of the 4 elements of $numbers are summed up: 1 + 2 + 3, which equals 6.
See the comments in the code below:
<?php
$numbers = array(1,2,3,4);
$total = count($numbers); // Gives 4
$sum = 0;
$output = "";
$i = 0; // $i = 0
foreach($numbers as $number) {
$i = $i + 1; // $i = 1, even at the first time
// after 3 passes $i is equal to $total (=4)
if ($i < $total) { // So, only 3 of the 4 elements of $number are honored
$sum = $sum + $number;
}
}
echo $sum; // Thus $sum = 1 + 2 + 3 = 6
// The last element (=4) is never summed up
?>
This would sum up all 4 elements, giving 10 as the result:
foreach($numbers as $number) {
if ($i < $total) {
$sum = $sum + $number;
}
$i = $i + 1;
}

Answer 2

<?php
$numbers = array(1,2,3,4);
$total = count($numbers); #value of $total is 4 here
$sum = 0;
$output = ""; #intital empty
$i = 0;
foreach($numbers as $number) {
$i = $i + 1;
if ($i < $total) {
$sum = $sum + $number;
}
}
echo $sum;
?>
You increment the $i by 1 so it becomes 1 which is smaller than $total(which is 4). Your program will add till $i become 4. It just add first three number in your array.
1+2+3=6.
That's why you are getting 6.
I hope you get it. :)

Answer 3

The condition limits the iterations. When $i is 4 it is no longer less than $total and so the last number doesn't get added.