Character classes and quantifiers in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to match any digit character using a regular expression.

PHP

<?php
$pattern = '/[1]/';
$string = 'My number is 1234';
if (preg_match($pattern, $string)) {
    echo 'Digit found';
} else {
    echo 'No digit found';
}
?>

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 which matches letters and digits, not only digits.

Using \s which matches whitespace characters.

The \d character class matches any digit (0-9).

2fill in blank

medium

Complete the code to match exactly three lowercase letters in a row.

PHP

<?php
$pattern = '/[a-z][1]/';
$string = 'abc def';
if (preg_match($pattern, $string)) {
    echo 'Match found';
} else {
    echo 'No match';
}
?>

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

A{3}

B{2,4}

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which matches one or more, not exactly three.

Using * which matches zero or more.

The quantifier {3} matches exactly three occurrences of the preceding character class.

3fill in blank

hard

Fix the error in the pattern to match one or more whitespace characters.

PHP

<?php
$pattern = '/\s[1]/';
$string = "Hello   World";
if (preg_match($pattern, $string)) {
    echo 'Whitespace found';
} else {
    echo 'No whitespace';
}
?>

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

A*

B+

C?

D{1,}

Attempts:

3 left

💡 Hint

Common Mistakes

Using ? which means zero or one occurrence.

Using * which means zero or more, but the question asks for one or more.

The quantifier + means one or more occurrences, perfect for matching one or more whitespace characters.

4fill in blank

hard

Fill both blanks to create a pattern that matches a string starting with one or more digits followed by exactly two letters.

PHP

<?php
$pattern = '/^[1][a-z][2]$/';
$string = '123ab';
if (preg_match($pattern, $string)) {
    echo 'Pattern matches';
} else {
    echo 'No match';
}
?>

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

A\d+

B[a-z]

C{2}

D[0-9]

Attempts:

3 left

💡 Hint

Common Mistakes

Using [0-9] without quantifier for digits.

Not specifying exact two letters with {2}.

The pattern \d+ matches one or more digits at the start, and {2} after a character class means exactly two occurrences.

5fill in blank

hard

Fill all three blanks to create a pattern that matches a string with exactly three uppercase letters, followed by one or more digits, and ending with zero or more whitespace characters.

PHP

<?php
$pattern = '/^[1][2][3]$/';
$string = 'ABC123   ';
if (preg_match($pattern, $string)) {
    echo 'Full match';
} else {
    echo 'No full match';
}
?>

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

A[A-Z]{3}

B\d+

C\s*

D[a-z]{3}

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase letters instead of uppercase.

Using wrong quantifiers for digits or whitespace.

The pattern matches exactly three uppercase letters [A-Z]{3}, then one or more digits \d+, and ends with zero or more whitespace characters \s*.