Preg_replace for substitution in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to replace all digits with a dash using preg_replace.

PHP

<?php
$text = "Call me at 123-456-7890.";
$result = preg_replace([1], '-', $text);
echo $result;
?>

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

A"/\s/"

B"/\w/"

C"/\d/"

D"/\D/"

Attempts:

3 left

💡 Hint

Common Mistakes

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

Using \s matches spaces, not digits.

Using \D matches non-digits, which is the opposite.

The pattern /\d/ matches any digit. Using it in preg_replace replaces all digits with '-'.

2fill in blank

medium

Complete the code to replace all vowels with '*' using preg_replace.

PHP

<?php
$text = "Hello World!";
$result = preg_replace([1], '*', $text);
echo $result;
?>

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

A"/\s/"

B"/[aeiou]/i"

C"/[bcdfg]/i"

D"/[0-9]/"

Attempts:

3 left

💡 Hint

Common Mistakes

Using digits or consonants in the pattern instead of vowels.

Forgetting the 'i' modifier to match uppercase vowels.

The pattern /[aeiou]/i matches vowels ignoring case. It replaces vowels with '*'.

3fill in blank

hard

Fix the error in the code to replace all spaces with underscores using preg_replace.

PHP

<?php
$text = "Replace spaces here.";
$result = preg_replace([1], '_', $text);
echo $result;
?>

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

A"/\s/"

B"/ /"

C"/\S/"

D"/\d/"

Attempts:

3 left

💡 Hint

Common Mistakes

Using \S matches non-whitespace, which is incorrect here.

Using \d matches digits, not spaces.

The pattern /\s/ matches any whitespace character including spaces. It replaces spaces with underscores.

4fill in blank

hard

Fill both blanks to replace all words starting with 'a' or 'A' with 'word' using preg_replace.

PHP

<?php
$text = "An apple a day keeps the doctor away.";
$result = preg_replace([1], [2], $text);
echo $result;
?>

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

A"/\b[aA]\w*/"

B"/\d+/"

C'word'

D'fruit'

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect patterns that don't match word boundaries.

Forgetting to quote the replacement string.

The pattern /\b[aA]\w*/ matches words starting with 'a' or 'A'. Replacing with 'word' substitutes those words.

5fill in blank

hard

Fill all three blanks to replace all digits with '#' only if they are at the start of the string using preg_replace.

PHP

<?php
$text = "123abc456";
$result = preg_replace([1], [2], $text, [3]);
echo $result;
?>

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

A"/^\d+/"

B'#'

C1

D"/\d+/"

Attempts:

3 left

💡 Hint

Common Mistakes

Using pattern without ^ matches digits anywhere.

Forgetting to quote the replacement string.

Not setting the limit to 1 causes all digits to be replaced.

The pattern /^\d+/ matches digits at the start. Replacement is '#'. Limit 1 ensures only the first match is replaced.