Function call and execution flow in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested function calls

What is the output of this Python code?

Python

def f(x):
    return x * 2

def g(y):
    return f(y) + 3

print(g(4))

A 7

B 8

C 11

D 14

💡 Hint

Remember to follow the order of function calls and operations step by step.

Function g calls f with y=4, so f(4) returns 8. Then g adds 3, so 8 + 3 = 11.

❓ Predict Output

intermediate

Value of variable after function call

What is the value of variable 'result' after running this code?

Python

def add_one(n):
    return n + 1

result = add_one(5)

A 6

B 5

C None

D Error

💡 Hint

Check what the function returns and what is assigned to 'result'.

The function adds 1 to 5, so result becomes 6.

❓ Predict Output

advanced

Output with recursive function

What is the output of this recursive function call?

Python

def countdown(n):
    if n == 0:
        return 'Done'
    else:
        return str(n) + ' ' + countdown(n-1)

print(countdown(3))

A Error

B "3 2 1 Done"

C "Done 3 2 1"

D "3 2 1 0 Done"

💡 Hint

Trace the function calls from n=3 down to 0.

The function concatenates numbers down to 1 and then adds 'Done'.

❓ Predict Output

advanced

Output with function modifying a list

What is printed after this code runs?

Python

def append_number(lst):
    lst.append(4)

numbers = [1, 2, 3]
append_number(numbers)
print(numbers)

A [1, 2, 3, 4]

B [4]

C [1, 2, 3]

D Error

💡 Hint

Think about how lists are passed to functions in Python.

The list is modified inside the function, so the original list has 4 appended.

❓ Predict Output

expert

Output of function with default and keyword arguments

What is the output of this code?

Python

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

print(greet('Alice'))
print(greet('Bob', greeting='Hi'))

A "Hi, Alice!\nHi, Bob!"

B "Hi, Alice!\nHello, Bob!"

C "Hello, Alice!\nHello, Bob!"

D "Hello, Alice!\nHi, Bob!"

💡 Hint

Check which greeting is used for each call.

First call uses default 'Hello', second call uses keyword argument 'Hi'.