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

Brane Opačič
Brane Opačič
6,686 Points

Functions question in "Making a Basic PHP website"

Hello, good people.

I just can't grasp the logic here - I think the concatenation is giving me trouble. Why is the answer 321, can someone walk me through?

Thank you so much!



$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;


2 Answers

Zachary Billingsley
Zachary Billingsley
6,187 Points


I'll try to break it down as best I can.

Here are your starting variables -> /********* $numbers = [1,2,3,4]; (This is another way to write an array) $total = 4; (count of the $numbers array) $sum = 0; (Doesn't seem to be used anywhere in the code though)

$output = ""; $i = 0; *********/

(1st loop) Inside your foreach loop, you start with $i = 1 ( $i = 0 + 1) and $number = 1 (the first index of your $numbers array). if ( 1 < 4 ) Which is TRUE $output = 1; (because the concatenation of 1 and "" is just 1)

(2nd loop) Now increment $i by 1 to get 2 and your $number = 2 (the second index of your $numbers array). if ( 2 < 4 ) Which is TRUE $output = 21; (because the concatenation of 2 and 1 is 21)

(3rd loop) Now increment $i by 1 to get 3 and your $number = 3(the third index of your $numbers array). if ( 3 < 4 ) Which is TRUE $output = 321; (because the concatenation of 3 and 21 is 321)

(4th loop) Now increment $i by 1 to get 4 and your $number = 4 (the fourth index of your $numbers array). if ( 4 < 4 ) Which is FALSE $output stays the same

echo $output; //Gives you 321

Hope that helps!

Brane Opačič
Brane Opačič
6,686 Points

Wow! Thanks, Zachary! I needed the push you just gave me to continue working hard. Thank you so much.