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

Lucas Santos
Lucas Santos
19,315 Points

Can someone please explain this code

Im stuck on this quiz and I believe it's asking me what this code would output on the screen.

<?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;

?>

3 Answers

When this particular piece of code starts executing, there are four variables initialized at the top. First, you can ignore $sum because it's not used elsewhere in the code. $i is 0, $total is 4 because there are 4 elements in the $numbers array, and $output is an empty string.

On the first iteration of foreach, $i gets immediately increased to 1. Then we check if it's smaller that $total. Because it is, the current number from the $numbers array (in this case it's the first element — 1) gets concatenated with the $output and the resulting string is assigned as the new value of the $output variable, which now equals to "1".

On the second iteration, $i is increased to 2. It's still smaller than $total, so now the second element of the array (2) is concatenated with $output ("1") and the resulting string ("21") is assigned as the new value of $output.

The same is true for the third iteration, only now the resulting string is "321".

In the fourth iteration, $i is now 4 and as it's not smaller than $total, no value re-assignment of $output happens.

So, the final output is the resulting string from the third iteration: 321.

Lucas Santos
Lucas Santos
19,315 Points

Hey so when ever you concatenate a number or value to an empty variable it will always add it to the left meaning the beginning of the empty string rite? I would think it would be like reading and it adds the numbers to the rite like 123 instead of 321 but I guess not.

Guillaume Maka
Guillaume Maka
Courses Plus Student 10,224 Points

To get 123 you just need to do the opposite

$output =  $output . $number;

That was your question ?

Guillaume Maka
PLUS
Guillaume Maka
Courses Plus Student 10,224 Points
<?php

// declare an array of 4 numbers
$numbers = array(1,2,3,4);

// assign the length of $number array to $total -> 4
$total = count($numbers);

// declare a variable $sum and initialize it to 0
$sum = 0;

// declare a variable $output and initialize it to an empty string
$output = "";

// declare a variable $i and initialize it to 0
$i = 0;

// do a foreach loop to grab each element in the array
foreach($numbers as $number) {
    // track how many element we have already take
    // ex: at the first iteration, $i = 0 + 1
    $i = $i + 1;

    // check we don't exceed the total sze of the array
    // ex: at the first iteration, $i = 1 , $total = 4, so 1 <  4 then enter into the if statement
    if ($i < $total) {

        // concatenate the given $number to the $output
        // ex: at the first iteration, $number = 1,  $ouptut = ''
        $output = $number . $output;
        // $output = '1' 
    }

}

// print the output to the screen
// $output = '321'
echo $output;

?>

Hope that will help you.

Lucas Santos
Lucas Santos
19,315 Points

Thanks a lot this helps!

Lucas Santos
Lucas Santos
19,315 Points

Thanks a lot this helps!