Why strings are mutable in Ruby - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to change the string content.

Ruby

str = "hello"
str[1] " world"
puts str

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

A<<

B+=

C==

D===

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which creates a new string instead of modifying.

In Ruby, the << operator appends to the original string, showing mutability.

2fill in blank

medium

Complete the code to replace part of the string.

Ruby

str = "hello"
str[1] 0, 5, "hi"
puts str

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

A[]=

Breplace

Cslice

Dsub

Attempts:

3 left

💡 Hint

Common Mistakes

Using sub which returns a new string without modifying original.

The []= method replaces part of the string in place, showing mutability.

3fill in blank

hard

Fix the error in the code to mutate the string.

Ruby

str = "hello"
str.[1](" world")
puts str

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

Asub

Bconcat

Cgsub

Dreplace

Attempts:

3 left

💡 Hint

Common Mistakes

Using sub or gsub which return new strings without mutating.

The concat method appends to the string in place, mutating it.

4fill in blank

hard

Fill both blanks to create a mutable string and modify it.

Ruby

str = [1]"hello"
str[2] " world"
puts str

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

A"hello"

BString.new(

C<<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which creates a new string instead of modifying.

Using String.new creates a mutable string object, and << appends to it.

5fill in blank

hard

Fill all three blanks to replace part of the string and show mutability.

Ruby

str = "hello"
str[1] 0, 5, [2]
puts str
puts str[3] "!"

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

A[]=

B"hi"

C<<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which creates new strings instead of mutating.

The []= method replaces part of the string, and << appends to it, both mutating the string.