Function definition and syntax in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the basic syntax to define a function in Python?

Use the def keyword, followed by the function name, parentheses (), and a colon :. Then indent the function body below. Example:

def my_function():
    print("Hello")

beginner

What does the return statement do inside a function?

It sends a value back to where the function was called. This lets the function give back a result. Without return, the function returns None by default.

beginner

Can a Python function have parameters? How are they used?

Yes, parameters are names inside the parentheses in the function definition. They act like placeholders for values you give when calling the function. Example:

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

intermediate

What happens if you call a function without parentheses?

You get a reference to the function itself, not the result of running it. To run the function and get its output, you must use parentheses, even if empty.

beginner

Why is indentation important in Python function definitions?

Indentation shows which lines belong inside the function. Python uses indentation instead of braces. Without correct indentation, Python will give an error or run code incorrectly.

Which keyword is used to define a function in Python?

A define

B function

C func

D def

The correct keyword to define a function in Python is def.

What will this function return if called without a return statement?

def add(a, b):
    c = a + b

A The sum of a and b

B None

C An error

D a + b as a string

Without a return statement, Python functions return None by default.

How do you call a function named say_hello with no parameters?

A say_hello()

B say_hello

C call say_hello

D def say_hello()

You call a function by writing its name followed by parentheses, even if empty.

What is the purpose of parameters in a function?

A To return values from the function

B To store the function's name

C To hold values passed into the function

D To indent the function body

Parameters are placeholders for values you pass into the function when calling it.

Why must the function body be indented in Python?

A Because Python uses indentation to group code blocks

B To separate the function from other code

C To make the code look pretty

D To add comments inside the function

Python uses indentation to know which lines belong inside the function or other blocks.

Explain how to define a simple function in Python that takes one parameter and returns a value.

Think about the parts you need to write a function that gives back a result.

Describe why indentation is important in Python function definitions and what happens if it is missing.

Consider how Python knows which lines belong inside the function.