Why generators are needed in PHP - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a generator function that yields numbers from 1 to 3.

PHP

<?php
function numbers() {
    yield [1];
}

foreach (numbers() as $num) {
    echo $num . " ";
}
?>

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

A3

B1

C0

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Yielding a number outside the desired range.

Using return instead of yield.

The yield keyword outputs values one at a time. Here, yielding 1 starts the sequence.

2fill in blank

medium

Complete the code to yield numbers from 1 to 3 inside a loop.

PHP

<?php
function numbers() {
    for ($i = 1; $i <= [1]; $i++) {
        yield $i;
    }
}

foreach (numbers() as $num) {
    echo $num . " ";
}
?>

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

A0

B5

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the loop limit too high or too low.

Using incorrect comparison operators.

The loop runs while $i is less than or equal to 3, yielding numbers 1, 2, and 3.

3fill in blank

hard

Fix the error in the generator function to yield squares of numbers from 1 to 3.

PHP

<?php
function squares() {
    for ($i = 1; $i <= 3; $i++) {
        yield $i [1] 2;
    }
}

foreach (squares() as $square) {
    echo $square . " ";
}
?>

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

A*

B+

C**

D//

Attempts:

3 left

💡 Hint

Common Mistakes

Using * instead of ** for exponentiation.

Using addition or integer division operators.

In PHP 7+, ** is the exponentiation operator, used here to square the number.

4fill in blank

hard

Fill both blanks to create a generator that yields only even numbers from 1 to 6.

PHP

<?php
function evenNumbers() {
    for ($i = 1; $i <= [1]; $i++) {
        if ($i [2] 2 == 0) {
            yield $i;
        }
    }
}

foreach (evenNumbers() as $num) {
    echo $num . " ";
}
?>

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

A6

B%

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect loop limits.

Using wrong operators in the if condition.

The loop runs up to 6, and the modulus operator % checks if the number is even.

5fill in blank

hard

Fill all three blanks to create a generator that yields keys and values from an array where values are greater than 10.

PHP

<?php
function filterArray($arr) {
    foreach ($arr as [1] => [2]) {
        if ([2] > 10) {
            yield [1] => [2];
        }
    }
}

$data = ['a' => 5, 'b' => 15, 'c' => 25];

foreach (filterArray($data) as $key => $value) {
    echo "$key: $value\n";
}
?>

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

A$key

B$value

C$val

D$k

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names in foreach and yield.

Mixing keys and values incorrectly.

The foreach loop uses $key and $value to iterate and yield key-value pairs where the value is greater than 10.