Default arguments in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a function with a default argument.

Python

def greet(name=[1]):
    print(f"Hello, {name}!")

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

A"Guest"

BGuest

Cname

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around string default values.

Using variable names without quotes as default.

The default argument must be a string, so it needs quotes. "Guest" is correct.

2fill in blank

medium

Which value should be passed to greet() so it prints 'Hello, Guest!'?

Python

def greet(name="Guest"):
    print(f"Hello, {name}!")

result = greet([1])

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

A"User"

BNone

C"Guest"

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Passing None which would print 'Hello, None!'.

Using an unquoted variable name instead of a string value.

Passing "Guest" explicitly produces the same output as calling with no arguments, since the default value is "Guest".

3fill in blank

hard

Fix the error in the function definition by completing the default argument correctly.

Python

def multiply(x, y=[1]):
    return x * y

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

A1

B"1"

C0

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string "1" instead of number 1.

Using None which causes errors in multiplication.

The default argument y should be a number, so 1 without quotes is correct.

4fill in blank

hard

Fill both blanks to create a function with two default arguments and call it with one argument.

Python

def order(item, quantity=[1], price=[2]):
    total = quantity * price
    print(f"Order: {quantity} {item}(s) for ${total}")

order("apple")

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

A1

B0

C0.5

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Setting quantity to 0 which results in zero total.

Using integer price when decimal is expected.

Quantity defaults to 1 and price to 0.5 to calculate total correctly.

5fill in blank

hard

Fill all three blanks to create a function with default arguments and call it with two arguments.

Python

def describe_pet(name=[1], species=[2], age=[3]):
    print(f"{name} is a {age}-year-old {species}.")

describe_pet("Buddy", "dog")

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

A"Unknown"

B"dog"

C3

D"Buddy"

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong default types like numbers for strings.

Not matching the order of arguments and defaults.

Default name is "Buddy" but overridden by argument, species default "dog", age default 3.

Practice

1. What is the main purpose of default arguments in Python functions?

easy

A. To create variables inside the function

B. To provide preset values for parameters if no argument is given

C. To make functions run faster

D. To force the user to always provide all arguments

Solution

1. Step 1: Understand default arguments

   Default arguments allow a function to have parameters with preset values if the caller does not provide them.

2. Step 2: Identify the purpose

   This makes the function easier to call without needing all arguments every time.

3. Final Answer:

   To provide preset values for parameters if no argument is given -> Option B

4. Quick Check:

   Default arguments = preset values [OK]

Hint: Default arguments fill in missing inputs automatically [OK]

Common Mistakes:

• Thinking default arguments speed up code
• Believing default arguments force all inputs
• Confusing default arguments with variable creation

2. Which of the following function definitions uses default arguments correctly?

easy

A. def greet(name='Friend', age):

B. def greet(name=, age=30):

C. def greet(name, age=30):

D. def greet(name, age=):

Solution

1. Step 1: Check default argument placement

   Parameters with default values must come after parameters without defaults.

2. Step 2: Analyze each option

   def greet(name='Friend', age): places a default before a non-default parameter, which is invalid syntax. Options C and D have syntax errors. def greet(name, age=30): correctly places the default argument after a required parameter.

3. Final Answer:

   def greet(name, age=30): -> Option C

4. Quick Check:

   Defaults after required params = correct syntax [OK]

Hint: Put default parameters after required ones [OK]

Common Mistakes:

• Placing default arguments before required ones
• Leaving default values empty
• Using invalid syntax for defaults

3. What is the output of this code?

def multiply(a, b=2):
    return a * b

print(multiply(4))
print(multiply(4, 3))

medium

A. Error

B. 6 and 12

C. 8 and 6

D. 8 and 12

Solution

1. Step 1: Understand default argument usage

   When multiply(4) is called, b uses its default value 2, so 4 * 2 = 8.

2. Step 2: Evaluate second call

   When multiply(4, 3) is called, b is 3, so 4 * 3 = 12.

3. Final Answer:

   8 and 12 -> Option D

4. Quick Check:

   Default used first call, explicit second call = 8 and 12 [OK]

Hint: Default used if argument missing, else explicit value [OK]

Common Mistakes:

• Assuming default is ignored when argument is given
• Confusing order of arguments
• Expecting error when default is used

4. Find the error in this function definition:

def add_numbers(x=5, y):
    return x + y

medium

A. Default argument before non-default argument causes SyntaxError

B. Missing return statement

C. Function name is invalid

D. No error, code runs fine

Solution

1. Step 1: Check parameter order

   Parameters with default values must come after parameters without defaults in Python.

2. Step 2: Identify error

   Here, x has a default but y does not, so this causes a SyntaxError.

3. Final Answer:

   Default argument before non-default argument causes SyntaxError -> Option A

4. Quick Check:

   Default before required param = SyntaxError [OK]

Hint: Non-default params must come before default ones [OK]

Common Mistakes:

• Ignoring parameter order rules
• Thinking missing return causes error here
• Assuming function name is invalid

5. You want a function that greets a user with their name and an optional greeting word (default is 'Hello'). Which function definition is correct and prints "Hi, Alice!" when called as greet('Alice', 'Hi') and "Hello, Bob!" when called as greet('Bob')?

hard

A. def greet(name, greeting='Hello'):
print(f"{greeting}, {name}!")

B. def greet(greeting='Hello', name):
print(f"{greeting}, {name}!")

C. def greet(name, greeting):
print(f"{greeting}, {name}!")

D. def greet(name='User', greeting='Hello'):
print(f"{name}, {greeting}!")

Solution

1. Step 1: Check parameter order and defaults

   Parameters with defaults must come after those without. def greet(name, greeting='Hello'): print(f"{greeting}, {name}!") has name first (no default), greeting second (default 'Hello').

2. Step 2: Verify behavior

   Calling greet('Alice', 'Hi') prints "Hi, Alice!". Calling greet('Bob') uses default greeting "Hello" and prints "Hello, Bob!".

3. Final Answer:

   def greet(name, greeting='Hello'): print(f"{greeting}, {name}!") -> Option A

4. Quick Check:

   Defaults after required params, works as expected [OK]

Hint: Put required params first, defaults after [OK]

Common Mistakes:

• Placing default param before required param
• Not providing default for optional greeting
• Using default for name causing unexpected calls