Methods with parameters in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of method with default and positional parameters

What is the output of this Python code?

Python

class Calculator:
    def multiply(self, x, y=2):
        return x * y

calc = Calculator()
print(calc.multiply(3))

A 6

B 3

C TypeError

D None

💡 Hint

Remember that y has a default value of 2 if not provided.

The method multiply takes x and y, with y defaulting to 2. Calling multiply(3) uses y=2, so 3*2=6.

❓ Predict Output

intermediate

Output when method parameters are passed by keyword

What will this code print?

Python

class Greeter:
    def greet(self, name, greeting='Hello'):
        print(f"{greeting}, {name}!")

g = Greeter()
g.greet(greeting='Hi', name='Alice')

A TypeError

B Hello, Alice!

C Hi, Alice!

D Hi, greeting!

💡 Hint

Check how keyword arguments match parameters.

The greet method is called with greeting='Hi' and name='Alice', so it prints 'Hi, Alice!'.

❓ Predict Output

advanced

Output of method with mutable default parameter

What is the output of this code?

Python

class Collector:
    def __init__(self):
        self.items = []
    def add(self, item, collection=[]):
        collection.append(item)
        return collection

c = Collector()
print(c.add('apple'))
print(c.add('banana'))

A ['apple']\n['banana']

B []\n[]

C TypeError

D ['apple']\n['apple', 'banana']

💡 Hint

Default mutable parameters keep their state between calls.

The default list 'collection' is shared between calls, so the second call appends 'banana' to the same list containing 'apple'.

❓ Predict Output

advanced

Output of method using *args and **kwargs

What does this code print?

Python

class Printer:
    def show(self, *args, **kwargs):
        print(args)
        print(kwargs)

p = Printer()
p.show(1, 2, a=3, b=4)

A (1, 2)\n{'a': 3, 'b': 4}

B [1, 2]\n{'a': 3, 'b': 4}

C TypeError

D (1, 2)\n[3, 4]

💡 Hint

*args collects positional arguments as a tuple, **kwargs collects keyword arguments as a dict.

The method prints the tuple of positional arguments and the dictionary of keyword arguments.

🧠 Conceptual

expert

Understanding parameter passing and object mutation

Consider this code. What is the output after calling modify_list?

Python

def modify_list(lst):
    lst.append(4)
    lst = [1, 2, 3]
    return lst

my_list = [0]
result = modify_list(my_list)
print(my_list)
print(result)

A [0]\n[1, 2, 3, 4]

B [0, 4]\n[1, 2, 3]

C [0, 4]\n[0, 4]

D [1, 2, 3]\n[1, 2, 3]

💡 Hint

Think about how lists are passed by reference and reassignment inside the function.

The original list 'my_list' is modified by append (so it becomes [0,4]). Then inside the function, lst is reassigned to a new list [1,2,3], which does not affect 'my_list'. The function returns the new list.