Variable-length arguments (*args) in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of function using *args with sum

What is the output of this Python code?

Python

def add_all(*args):
    return sum(args)

result = add_all(1, 2, 3, 4)
print(result)

A 10

B 1234

C TypeError

D None

💡 Hint

Remember that *args collects all arguments into a tuple and sum adds them up.

The function add_all takes any number of arguments and sums them. So 1+2+3+4 equals 10.

❓ Predict Output

intermediate

Output when *args is empty

What will this code print?

Python

def greet(*args):
    if args:
        print('Hello, ' + args[0])
    else:
        print('Hello, stranger')

greet()

A TypeError

B Hello,

C IndexError

D Hello, stranger

💡 Hint

Check what happens when no arguments are passed and how the if condition works.

Since no arguments are passed, args is empty, so the else branch runs printing 'Hello, stranger'.

❓ Predict Output

advanced

Output of function with *args and unpacking

What is the output of this code?

Python

def multiply(*args):
    result = 1
    for num in args:
        result *= num
    return result

numbers = [2, 3, 4]
print(multiply(*numbers))

A 24

B [2, 3, 4]

C 9

D TypeError

💡 Hint

The * operator unpacks the list into separate arguments.

The list [2,3,4] is unpacked into arguments 2,3,4. Multiplying them gives 2*3*4=24.

❓ Predict Output

advanced

Output when mixing *args with normal parameters

What does this code print?

Python

def describe(name, *args):
    print(f'Name: {name}')
    print(f'Other info: {args}')

describe('Alice', 25, 'Engineer')

A

Name: Alice
Other info: 25, Engineer

B

Name: Alice
Other info: (25, 'Engineer')

C

Name: Alice
Other info: [25, 'Engineer']

D TypeError

💡 Hint

Check how *args collects extra arguments as a tuple.

The first argument goes to name, the rest are collected in args as a tuple (25, 'Engineer').

🧠 Conceptual

expert

Why use *args in function definitions?

Which of these best explains why *args is used in Python functions?

A To make the function return multiple values.

B To force the function to accept exactly one argument.

C To allow the function to accept any number of positional arguments as a tuple.

D To collect keyword arguments into a dictionary.

💡 Hint

Think about how *args collects arguments.

*args collects all extra positional arguments into a tuple, allowing flexible argument counts.

Practice

1. What does *args do in a Python function?

easy

A. Allows the function to accept any number of extra positional arguments

B. Allows the function to accept only keyword arguments

C. Restricts the function to accept exactly one argument

D. Makes the function return multiple values

Solution

1. Step 1: Understand the role of *args

   *args collects extra positional arguments passed to a function into a tuple.

2. Step 2: Compare options with this behavior

   Only Allows the function to accept any number of extra positional arguments correctly describes this behavior; others describe different concepts.

3. Final Answer:

   Allows the function to accept any number of extra positional arguments -> Option A

4. Quick Check:

   *args = flexible positional inputs [OK]

Hint: Remember *args packs extra positions into a tuple [OK]

Common Mistakes:

• Confusing *args with **kwargs
• Thinking *args limits arguments
• Assuming *args returns multiple values

2. Which of the following is the correct syntax to define a function that accepts variable-length positional arguments?

easy

A. def func(args*):

B. def func(*args):

C. def func(**args):

D. def func(args**):

Solution

1. Step 1: Recall the syntax for variable-length positional arguments

   The correct syntax uses an asterisk before the parameter name: *args.

2. Step 2: Match options with correct syntax

   def func(*args): matches the correct syntax; others are invalid or for different purposes.

3. Final Answer:

   def func(*args): -> Option B

4. Quick Check:

   Star before name = variable positional args [OK]

Hint: Use * before parameter name for variable positional args [OK]

Common Mistakes:

• Using **args instead of *args
• Placing * after the parameter name
• Confusing syntax with keyword arguments

3. What is the output of the following code?

def add_numbers(*args):
    return sum(args)

print(add_numbers(1, 2, 3, 4))

medium

A. 10

B. 1234

C. TypeError

D. None

Solution

1. Step 1: Understand how *args works in the function

   The function collects all arguments into a tuple and sums them using sum().

2. Step 2: Calculate the sum of the arguments

   1 + 2 + 3 + 4 = 10, so the function returns 10.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   Sum of (1,2,3,4) = 10 [OK]

Hint: Sum all *args values to get total [OK]

Common Mistakes:

• Concatenating numbers as strings
• Expecting a TypeError for multiple args
• Forgetting that *args is a tuple

4. Identify the error in this function definition:

def greet(*names):
    for name in names
        print(f"Hello, {name}!")

medium

A. print statement syntax error

B. Incorrect use of *args syntax

C. Missing colon after for loop

D. Function cannot have *args

Solution

1. Step 1: Check the for loop syntax

   The for loop line is missing a colon at the end, which is required in Python.

2. Step 2: Verify other parts of the function

   The *names syntax and print statement are correct; the function can have *args.

3. Final Answer:

   Missing colon after for loop -> Option C

4. Quick Check:

   For loops need a colon [:] [OK]

Hint: Check colons after for, if, while statements [OK]

Common Mistakes:

• Forgetting colon after for loop
• Confusing *args with **kwargs
• Incorrect indentation

5. How can you write a function that accepts any number of positional arguments and returns a list of their squares?

hard

A. def squares(args): return [x**2 for x in args]

B. def squares(*args): return x**2 for x in args

C. def squares(**args): return [x**2 for x in args]

D. def squares(*args): return [x**2 for x in args]

Solution

1. Step 1: Use *args to accept variable positional arguments

   The function parameter must be *args to accept any number of positional arguments.

2. Step 2: Return a list of squares using list comprehension

   Use [x**2 for x in args] to square each argument and collect results in a list.

3. Final Answer:

   def squares(*args): return [x**2 for x in args] -> Option D

4. Quick Check:

   Use *args and list comprehension for squares [OK]

Hint: Use *args and list comprehension for flexible squares [OK]

Common Mistakes:

• Using **args instead of *args
• Forgetting to return a list
• Incorrect comprehension syntax