Dynamic typing vs strong typing in Ruby - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign a string to the variable.

Ruby

name = [1]

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

A"Alice"

B42

Ctrue

D:symbol

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number or boolean instead of a string.

In Ruby, strings are written inside double quotes. Here, "Alice" is a string.

2fill in blank

medium

Complete the code to add two numbers.

Ruby

sum = 10 [1] 5

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

A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

The plus sign (+) adds two numbers together in Ruby.

3fill in blank

hard

Fix the error in the code by choosing the correct method to convert a number to a string.

Ruby

number = 100
text = number.[1]

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

Ato_sym

Bto_i

Cto_s

Dto_a

Attempts:

3 left

💡 Hint

Common Mistakes

Using to_i which converts to integer, not string.

In Ruby, to_s converts a number to a string.

4fill in blank

hard

Fill both blanks to create a hash with keys as symbols and values as strings.

Ruby

person = { [1]: [2] }

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

A:name

B"Bob"

Cname

DBob

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string as a key without colon or unquoted value.

In Ruby, hash keys can be symbols like :name, and values can be strings like "Bob".

5fill in blank

hard

Fill all three blanks to create a method that takes a parameter and returns its class name as a string.

Ruby

def get_type([1])
  [2].class.[3]
end

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

Avalue

Cto_s

Dclass_name

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong parameter name or method that doesn't convert to string.

The method takes a parameter named value. Then it calls value.class.to_s to get the class name as a string.

Practice

1. Which statement best describes Ruby's typing system?

easy

A. Ruby is dynamically typed and strongly typed.

B. Ruby is statically typed and weakly typed.

C. Ruby is statically typed and strongly typed.

D. Ruby is dynamically typed and weakly typed.

Solution

1. Step 1: Understand dynamic typing

   Dynamic typing means variables can hold any type and change types anytime during execution.

2. Step 2: Understand strong typing

   Strong typing means the language prevents mixing incompatible types without explicit conversion.

3. Final Answer:

   Ruby is dynamically typed and strongly typed. -> Option A

4. Quick Check:

   Dynamic + Strong = C [OK]

Hint: Remember Ruby allows type changes but checks type safety [OK]

Common Mistakes:

• Confusing dynamic with static typing
• Thinking Ruby allows unsafe type mixing
• Mixing weak and strong typing concepts

2. Which Ruby code snippet shows dynamic typing in action?

easy

A. x = 10; x = "hello"

B. int x = 10; x = "hello"

C. var x: Integer = 10; x = "hello"

D. let x = 10; x = true

Solution

1. Step 1: Identify Ruby syntax

   Ruby allows assigning different types to the same variable without error.

2. Step 2: Check each option

   x = 10; x = "hello" uses Ruby syntax and changes x from integer to string, showing dynamic typing.

3. Final Answer:

   x = 10; x = "hello" -> Option A

4. Quick Check:

   Variable changes type dynamically = A [OK]

Hint: Look for variable reassignment with different types in Ruby syntax [OK]

Common Mistakes:

• Choosing code with static typing syntax
• Confusing variable declaration styles
• Ignoring language-specific syntax rules

3. What will be the output of this Ruby code?

def add(a, b)
  a + b
end

puts add(5, "10")

medium

A. 15

B. TypeError

C. 510

D. nil

Solution

1. Step 1: Analyze the method call

   The method add tries to add an integer (5) and a string ("10") using + operator.

2. Step 2: Understand Ruby's strong typing

   Ruby does not automatically convert types for +; adding integer and string causes a TypeError.

3. Final Answer:

   TypeError -> Option B

4. Quick Check:

   Strong typing prevents int + string = B [OK]

Hint: Adding different types without conversion causes TypeError [OK]

Common Mistakes:

• Assuming automatic string conversion
• Expecting concatenation of numbers and strings
• Ignoring Ruby's type safety rules

4. Identify the error in this Ruby code:

def multiply(x, y)
  x * y
end

result = multiply(3, "4")
puts result

medium

A. NameError for undefined variable

B. SyntaxError due to method definition

C. No error, outputs 12

D. TypeError due to multiplying integer and string

Solution

1. Step 1: Check method parameters and call

   The method multiply is called with an integer (3) and a string ("4").

2. Step 2: Understand Ruby's type rules for *

   Multiplying integer by string without conversion causes a TypeError in Ruby.

3. Final Answer:

   TypeError due to multiplying integer and string -> Option D

4. Quick Check:

   Strong typing blocks int * string = A [OK]

Hint: Check operand types for * operator to avoid TypeError [OK]

Common Mistakes:

• Thinking Ruby auto-converts string to integer
• Assuming no error on mixed types
• Confusing SyntaxError with TypeError

5. You want to write a Ruby method that adds two values but safely handles if one is a string representing a number. Which approach best uses Ruby's dynamic and strong typing?

hard

A. Convert both to strings and concatenate.

B. Add values directly without conversion.

C. Convert both to integers before adding using to_i method.

D. Use static type declarations for parameters.

Solution

1. Step 1: Understand dynamic typing flexibility

   Ruby variables can hold any type, so inputs can be string or integer.

2. Step 2: Use strong typing safety

   To avoid TypeError, convert strings to integers explicitly before adding.

3. Step 3: Evaluate options

   Converting both to integers using to_i before adding is safe. Adding directly risks TypeError. Static type declarations are invalid in Ruby. Converting to strings performs concatenation instead of addition.

4. Final Answer:

   Convert both to integers before adding using to_i method. -> Option C

5. Quick Check:

   Dynamic + Strong typing = explicit conversion [OK]

Hint: Convert strings to numbers before math to avoid errors [OK]

Common Mistakes:

• Ignoring type conversion before arithmetic
• Assuming Ruby auto-converts types
• Using static typing syntax in Ruby