Regular expressions in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to find matches of the pattern 'cat' in the text.

MATLAB

matches = regexp(text, '[1]');

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

A'dog'

B'cat'

C'bat'

D'rat'

Attempts:

3 left

💡 Hint

Common Mistakes

Using double quotes instead of single quotes for the pattern.

Using a pattern that does not exist in the text.

The pattern 'cat' correctly matches the substring 'cat' in the text.

2fill in blank

medium

Complete the code to extract all words starting with 'a' or 'A' from the text.

MATLAB

words = regexp(text, '[1]', 'match');

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

A'\b[aA]\w*\b'

B'\d+'

C'cat'

D'\s'

Attempts:

3 left

💡 Hint

Common Mistakes

Not using word boundaries, causing partial matches.

Using '\d+' which matches digits, not words.

The pattern '\b[aA]\w*\b' matches words starting with 'a' or 'A'.

3fill in blank

hard

Fix the error in the code to find the position of the first digit in the string.

MATLAB

pos = regexp(str, '[1]');

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

A'\D'

B'[a-zA-Z]'

C'\d'

D'\s'

Attempts:

3 left

💡 Hint

Common Mistakes

Using '[a-zA-Z]' which matches letters, not digits.

Using '\D' which matches non-digit characters.

The pattern '\d' matches any digit character, so it finds the first digit position.

4fill in blank

hard

Fill both blanks to extract all email addresses from the text.

MATLAB

emails = regexp(text, '[1]', '[2]');

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

A'[\w\.]+@[\w\.]+\.[a-zA-Z]{2,}'

B'start'

C'match'

D'end'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'start' or 'end' instead of 'match' to get the actual emails.

Using an incomplete or incorrect email pattern.

The pattern matches typical email addresses, and 'match' returns the matched strings.

5fill in blank

hard

Fill all three blanks to replace all whitespace sequences with a single dash '-' in the string.

MATLAB

newStr = regexprep(str, '[1]', '[2]', '[3]');

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

A'\s+'

B'-'

C'all'

D'once'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'once' which replaces only the first match.

Using incorrect pattern that does not match whitespace sequences.

'\s+' matches one or more whitespace characters, '-' is the replacement, and 'all' replaces all occurrences.