Split and join methods in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to split the string into an array of words.

Ruby

words = "hello world ruby".[1](" ")

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

Ajoin

Bconcat

Csplit

Dreplace

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'join' instead of 'split' which combines arrays into strings.

Forgetting to provide a separator.

The split method divides a string into an array based on the given separator.

2fill in blank

medium

Complete the code to join the array elements into a single string separated by commas.

Ruby

result = ["apple", "banana", "cherry"].[1](",")

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

Aselect

Bsplit

Cmap

Djoin

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'split' which breaks strings instead of joining arrays.

Not providing a separator string.

The join method combines array elements into a string with the given separator.

3fill in blank

hard

Fix the error in the code to split the string by commas.

Ruby

items = "red,green,blue".[1](",")

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

Ajoin

Bsplit

Cconcat

Dreplace

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'join' which is for arrays, not strings.

Using 'replace' which changes content but does not split.

To break a string into parts by commas, use split with ',' as separator.

4fill in blank

hard

Fill both blanks to create a hash where keys are words and values are their lengths for words longer than 3 letters.

Ruby

lengths = {}; words.each { |word| lengths[[1]] = [2] if word.length > 3 }

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

Aword

Bword.length

Cword.size

Dword.upcase

Attempts:

3 left

💡 Hint

Common Mistakes

Using word.size instead of word.length (both work but only one is correct here).

Using word.upcase which changes the word but is not length.

The key should be the word itself, and the value should be its length using word.length.

5fill in blank

hard

Fill all three blanks to create a string of uppercase words joined by a dash, only including words longer than 3 letters.

Ruby

result = words.select { |w| w.length > [1] }.map { |w| w.[2] }.[3]("-")

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

A3

Bupcase

Cjoin

Ddowncase

Attempts:

3 left

💡 Hint

Common Mistakes

Using length > 4 instead of > 3 changes the filter.

Using downcase instead of upcase.

Using split instead of join at the end.

We select words longer than 3 letters, convert them to uppercase, then join with dashes.

Practice

1. What does the Ruby method split do when called on a string?

easy

A. It divides the string into an array based on a separator.

B. It combines array elements into a single string.

C. It changes all characters to uppercase.

D. It removes spaces from the string.

Solution

1. Step 1: Understand the purpose of split

   The split method breaks a string into parts wherever a separator is found.

2. Step 2: Identify the output type

   After splitting, the output is an array containing the separated parts of the string.

3. Final Answer:

   It divides the string into an array based on a separator. -> Option A

4. Quick Check:

   split = divide string into array [OK]

Hint: Split cuts strings into arrays at separators [OK]

Common Mistakes:

• Thinking split joins array elements
• Confusing split with uppercase conversion
• Assuming split removes spaces without separator

2. Which of the following is the correct syntax to join an array ["a", "b", "c"] into a string separated by dashes in Ruby?

easy

A. ["a", "b", "c"].split("-")

B. ["a", "b", "c"].join("-")

C. "a-b-c".join(["a", "b", "c"])

D. "a-b-c".split(["a", "b", "c"])

Solution

1. Step 1: Identify the method to combine array elements

   The join method is used on arrays to create a string with a separator.

2. Step 2: Check the syntax for join with a separator

   The syntax is array.join(separator), so ["a", "b", "c"].join("-") is correct.

3. Final Answer:

   ["a", "b", "c"].join("-") -> Option B

4. Quick Check:

   join(array) with separator = correct syntax [OK]

Hint: Use array.join(separator) to combine elements [OK]

Common Mistakes:

• Using split instead of join to combine
• Calling join on a string instead of array
• Passing array as argument to split or join incorrectly

3. What is the output of this Ruby code?

sentence = "apple,banana,cherry"
fruits = sentence.split(",")
result = fruits.join(" & ")
puts result

medium

A. apple & banana & cherry

B. apple,banana,cherry

C. apple banana cherry

D. ["apple", "banana", "cherry"]

Solution

1. Step 1: Split the string by commas

   The split(",") breaks the string into ["apple", "banana", "cherry"].

2. Step 2: Join the array with " & " separator

   The join(" & ") combines the array elements into the string "apple & banana & cherry".

3. Final Answer:

   apple & banana & cherry -> Option A

4. Quick Check:

   split then join with & = apple & banana & cherry [OK]

Hint: Split by comma, join with & gives 'apple & banana & cherry' [OK]

Common Mistakes:

• Expecting original string without changes
• Confusing split and join order
• Thinking join adds commas automatically

4. The following Ruby code is intended to split a string into words and then join them with a space, but it raises an error. What is the problem?

text = "hello world"
words = text.split
joined = words.join
puts joined()

medium

A. The variable words is not an array.

B. The method split requires an argument.

C. The call joined() is incorrect syntax.

D. The join method cannot be called without a separator.

Solution

1. Step 1: Check the method calls

   split without arguments splits on whitespace correctly. join can be called without arguments to join with empty string.

2. Step 2: Identify the error in puts joined()

   In Ruby, calling a variable like a method with parentheses joined() causes an error because joined is a string, not a method.

3. Final Answer:

   The call joined() is incorrect syntax. -> Option C

4. Quick Check:

   Calling string like method with () = error [OK]

Hint: Don't add () when printing variables in Ruby [OK]

Common Mistakes:

• Thinking split needs an argument always
• Assuming join requires a separator
• Calling variables as methods with parentheses

5. Given a string data = "red;green;blue;yellow", write Ruby code to split it into an array, remove the color "blue", and then join the remaining colors with commas. What is the correct output?

hard

A. "red;green;yellow"

B. "red,green,blue,yellow"

C. "red green yellow"

D. "red,green,yellow"

Solution

1. Step 1: Split the string by semicolons

   Using split(";") on data gives ["red", "green", "blue", "yellow"].

2. Step 2: Remove "blue" from the array

   Remove "blue" by using array.delete("blue") or array.reject!.

3. Step 3: Join the remaining elements with commas

   Joining with join(",") results in "red,green,yellow".

4. Final Answer:

   "red,green,yellow" -> Option D

5. Quick Check:

   Split by ;, remove blue, join by , = red,green,yellow [OK]

Hint: Split by ; remove item, join by , for final string [OK]

Common Mistakes:

• Forgetting to remove "blue" before joining
• Joining with wrong separator
• Using split without argument or wrong separator