Why regex is powerful in Ruby - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

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

Ruby

text = "I love programming in Ruby"
puts text =~ /[1]/ ? "Found" : "Not found"

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

ARuby

BPython

CJava

DC++

Attempts:

3 left

💡 Hint

Common Mistakes

Using a word not present in the string, causing no match.

The regex /Ruby/ matches the word 'Ruby' in the string, so the output is 'Found'.

2fill in blank

medium

Complete the code to find all words starting with 'b' in the string.

Ruby

text = "bat ball cat box"
matches = text.scan(/[1]\w*/)
puts matches.join(", ")

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

Ad

Bc

Ca

Db

Attempts:

3 left

💡 Hint

Common Mistakes

Using a letter that does not match any word start.

The regex /b\w*/ matches words starting with 'b'. The output will be 'bat, ball, box'.

3fill in blank

hard

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

Ruby

email = "[e-mail]"
puts email.match(/\A[\w.+-]+@[1]\.[a-z]{2,}\z/i) ? "Valid" : "Invalid"

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A[a-z]+

B[0-9]+

C[a-z0-9-]+

D[A-Z]+

Attempts:

3 left

💡 Hint

Common Mistakes

Using only letters or digits, missing hyphens in domain.

The regex part [a-z0-9-]+ correctly matches domain names with letters, digits, and hyphens.

4fill in blank

hard

Fill both blanks to create a regex that matches a date in 'YYYY-MM-DD' format.

Ruby

date = "2024-06-15"
pattern = /\A[1]-[2]-\d{2}\z/
puts date.match?(pattern) ? "Date valid" : "Date invalid"

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

A\d{4}

B\d{2}

C[a-z]{4}

D[0-9]{3}

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong digit counts or letters instead of digits.

The regex \d{4}-\d{2}-\d{2} matches dates like '2024-06-15' with four digits year and two digits month and day.

5fill in blank

hard

Fill all three blanks to create a hash that maps words to their lengths only if length is greater than 3.

Ruby

words = ["ruby", "is", "fun", "and", "powerful"]
lengths = { [1]: [2] for [3] in words if [2] > 3 }

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

Aword

Blen(word)

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names or missing the length condition.

The hash comprehension uses 'word' as key, 'len(word)' as value, iterating over 'word' in words, filtering length > 3.