Array reduce function in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the sum of all numbers in the array using array_reduce.

PHP

<?php
$numbers = [1, 2, 3, 4];
$sum = array_reduce($numbers, [1]);
echo $sum;
?>

Drag options to blanks, or click blank then click option'

Afunction($carry, $item) { return $carry + $item; }

Bfunction($carry, $item) { return $carry * $item; }

Cfunction($carry, $item) { return $item - $carry; }

Dfunction($carry, $item) { return $carry / $item; }

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of addition in the callback.

Forgetting to return the sum inside the callback.

The array_reduce function takes an array and a callback function. The callback combines elements. To sum, the callback adds $carry and $item.

2fill in blank

medium

Complete the code to calculate the product of all numbers in the array using array_reduce.

PHP

<?php
$numbers = [1, 2, 3, 4];
$product = array_reduce($numbers, [1], 1);
echo $product;
?>

Drag options to blanks, or click blank then click option'

Afunction($carry, $item) { return $carry + $item; }

Bfunction($carry, $item) { return $item / $carry; }

Cfunction($carry, $item) { return $carry - $item; }

Dfunction($carry, $item) { return $carry * $item; }

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication.

Not setting the initial value to 1.

To get the product of all numbers, the callback multiplies $carry by $item. The initial value is 1 to avoid zeroing the product.

3fill in blank

hard

Fix the error in the callback function to correctly concatenate all strings in the array.

PHP

<?php
$words = ['Hello', ' ', 'World', '!'];
$result = array_reduce($words, [1], '');
echo $result;
?>

Drag options to blanks, or click blank then click option'

Afunction($carry, $item) { return $carry . $item; }

Bfunction($carry, $item) { return $carry - $item; }

Cfunction($carry, $item) { return $item . $carry; }

Dfunction($carry, $item) { return $carry * $item; }

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication operators instead of concatenation.

Concatenating in the wrong order.

To join strings, the callback should concatenate $carry and $item using the dot operator ..

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their lengths as values using array_reduce.

PHP

<?php
$words = ['apple', 'banana', 'cherry'];
$lengths = array_reduce($words, function($carry, $word) {
    $carry[[1]] = [2];
    return $carry;
}, []);
print_r($lengths);
?>

Drag options to blanks, or click blank then click option'

A$word

Bstrlen($word)

C$carry

Dcount($word)

Attempts:

3 left

💡 Hint

Common Mistakes

Using $carry as key or value incorrectly.

Using count() instead of strlen().

The key should be the word itself ($word), and the value should be its length using strlen($word).

5fill in blank

hard

Fill all three blanks to filter and sum only numbers greater than 10 using array_reduce.

PHP

<?php
$numbers = [5, 12, 7, 20, 3];
$sum = array_reduce($numbers, function($carry, $num) {
    if ($num [1] 10) {
        $carry [2]= $num;
    }
    return $carry;
}, [3]);
echo $sum;
?>

Drag options to blanks, or click blank then click option'

A>

B+

C0

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than operator instead of greater than.

Not initializing carry to zero.

Using wrong operator for addition.

The condition checks if the number is greater than 10 (>). If true, add it to $carry using +=. The initial value is 0.