Return values

Getting results from functions

So far, our functions have printed output. But often you want functions to calculate something and give you the result to use elsewhere.

# This function only prints
def add_print(a, b):
    print(a + b)

# This function returns a value
def add_return(a, b):
    return a + b

# Now you can use the result
result = add_return(5, 3)
print(f"The result is {result}")  # The result is 8

The return statement

Use return to send a value back from a function:

def calculate_area(width, height):
    area = width * height
    return area

# Store the returned value
room_area = calculate_area(10, 12)
print(f"Room size: {room_area} sq ft")  # Room size: 120 sq ft

When Python hits a return statement, it immediately exits the function. Any code after return won’t run.

Using returned values

Returned values can be used in many ways:

def double(number):
    return number * 2

# Store in variable
result = double(5)

# Use in expressions
total = double(5) + double(3)  # 10 + 6 = 16

# Pass to other functions
print(double(10))  # 20

# Use in conditions
if double(7) > 10:
    print("Big number!")

Returning multiple values

Python can return multiple values as a tuple:

def get_min_max(numbers):
    return min(numbers), max(numbers)

# Get both values
minimum, maximum = get_min_max([5, 2, 8, 1, 9])
print(f"Min: {minimum}, Max: {maximum}")  # Min: 1, Max: 9

# Or as a tuple
result = get_min_max([5, 2, 8, 1, 9])
print(result)  # (1, 9)

Return vs print

Understanding the difference is crucial:

def get_greeting_print(name):
    print(f"Hello, {name}!")  # Just displays

def get_greeting_return(name):
    return f"Hello, {name}!"  # Gives back value

# Can't use print version's output
message = get_greeting_print("Alice")  # Prints but returns None
print(message)  # None

# Can use return version's output
message = get_greeting_return("Alice")  # Returns the string
print(message.upper())  # HELLO, ALICE!

Use return when you need to use the result elsewhere. Use print when you just want to display information.

Functions without return

Functions without explicit return statements return None:

def greet(name):
    print(f"Hello, {name}!")
    # No return statement

result = greet("Alice")  # Prints: Hello, Alice!
print(result)  # None

Common mistakes

Forgetting to return

# Wrong - calculates but doesn't return
def calculate_total(items):
    total = sum(items)
    # Forgot return!

# Right
def calculate_total(items):
    total = sum(items)
    return total

Code after return

# Wrong - code after return never runs
def get_status():
    return "Done"
    print("This never prints!")  # Unreachable

# Right - return last
def get_status():
    print("Checking status...")
    return "Done"

Printing instead of returning

# Wrong - prints instead of returning
def multiply(a, b):
    print(a * b)

result = multiply(3, 4)  # Prints 12
total = result + 10      # Error! result is None

# Right - return the value
def multiply(a, b):
    return a * b

What’s next?

Now that you know functions, let’s learn how to use external libraries and APIs to extend Python’s capabilities!

External tools

Use libraries and APIs

Functions

External tools

Practical Python

Error handling

Classes

Getting results from functions

The return statement

Using returned values

Returning multiple values

Return vs print

Functions without return

Common mistakes

What’s next?

External tools

​Getting results from functions

​The return statement

​Using returned values

​Returning multiple values

​Return vs print

​Functions without return

​Common mistakes

​What’s next?

External tools

Getting results from functions

The return statement

Using returned values

Returning multiple values

Return vs print

Functions without return

Common mistakes

What’s next?