Why regex is needed in PHP - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the string contains the word 'apple'.

PHP

<?php
$string = "I like apples.";
if (preg_match([1], $string)) {
    echo "Found apple!";
}
?>

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

A"^apple$"

B"apple"

C"/apple/i"

D"/apple/"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word without slashes as pattern causes errors.

Forgetting to use regex delimiters.

The preg_match function requires a pattern enclosed in delimiters like slashes. So "/apple/" is the correct regex pattern.

2fill in blank

medium

Complete the code to replace all digits in the string with '#'.

PHP

<?php
$text = "My phone is 123-456-7890.";
$result = preg_replace([1], '#', $text);
echo $result;
?>

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

A"/\d/"

B"/\w/"

C"/\s/"

D"/\D/"

Attempts:

3 left

💡 Hint

Common Mistakes

Using \w matches letters and digits, not just digits.

Using \s matches spaces, not digits.

The regex /\d/ matches any digit. So it replaces all digits with '#'.

3fill in blank

hard

Fix the error in the regex pattern to match an email address.

PHP

<?php
$email = "[e-mail]";
if (preg_match([1], $email)) {
    echo "Valid email.";
} else {
    echo "Invalid email.";
}
?>

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

A"^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,6}$"

B"/^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,6}$/"

C"/^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,6}$/i"

D"/^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,6}/"

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting delimiters causes syntax errors.

Leaving out anchors may cause partial matches.

The regex pattern must be enclosed in delimiters like slashes. Option B correctly uses slashes and anchors.

4fill in blank

hard

Fill both blanks to create a dictionary of words and their lengths for words longer than 3 characters.

PHP

<?php
$words = ['cat', 'elephant', 'dog', 'horse'];
$lengths = array_filter(array_map(function($word) {
    return strlen($word);
}, $words), function($word) {
    return $word [1] 3;
});
print_r($lengths);
?>

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

A==

B<

C>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using < or == will not filter correctly.

Using != will include unwanted words.

The code filters words with length greater than 3, so the operator should be >.

5fill in blank

hard

Fill all three blanks to create an associative array of uppercase words and their lengths for words longer than 4 characters.

PHP

<?php
$words = ['apple', 'bat', 'carrot', 'dog'];
$result = array_filter(array_combine(array_map(function($word) {
    return [1];
}, $words), array_map(function($word) {
    return [2];
}, $words)), function($length) {
    return $length [3] 4;
});
print_r($result);
?>

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

Astrtoupper($word)

Bstrlen($word)

C>

Dstrtolower($word)

Attempts:

3 left

💡 Hint

Common Mistakes

Using strtolower instead of strtoupper.

Using wrong comparison operators like < or ==.

The keys are uppercase words (strtoupper($word)), values are lengths (strlen($word)), and filter keeps lengths greater than 4 (>).