No correct answer for two questions at Working With Functions of Build Simple PHP Application

HI Jason,

I'm feeling pretty dense right now, but I don't understand your answer. I'm not understanding how each variable is interacting with each other. Could you talk me through how the loop is working? A step by step explanation of how the first output ends up as 1. I thought I understood loops, but for some reason I'm not wrapping my head around this one.

Hi S Ananda ,

I'll repost the for loop code here for reference:

<?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) {
        $output = $number . $output;
    }
}
echo $output;
?>

Since there are 4 numbers in the array, the foreach loop will loop a total of 4 times.

First time through the loop -

$number will have the value 1 since that was the first number in the array.

$i gets incremented by 1. It was initialized to 0 before the loop so $i now equals 1.

The if condition is checking if $i is less than $total which was initialized to 4 since that's how many numbers are in the array. Since 1 < 4 is true the $output statement will be executed.

$output = $number . $output means, take the value of $number and then concatenate onto the end of it the value of $output and then store that value back in $output.

$number currently equals 1 and $output is still the empty string that it was initialized too before the loop. So you have $output = 1 . "": That gives the string "1" because adding on an empty string doesn't change anything. The new value of $output is now "1".

2nd time through the loop

$i now becomes 2.

The condition 2 < 4 is true so the $output statement gets executed.

Remember that the current value of $output is "1" and $number is now 2 so the assignment statement becomes $output = 2 . "1" This produces the string "21" and becomes the new value for $output.

3rd time through the loop

$i becomes 3 and number is also 3.

The condition 3 < 4 is true so we have $output = 3 . "21"; $output now has the value "321".

4th and final time through the loop

$i is now 4

The condition 4 < 4 is now false and the assignment statement won't be executed this time. $output keeps its current value of "321".

So the final output from the echo after the loop is "321".

Let me know if that helps clear it up for you.

Yikes, should be slow and steady wins the race...