Introduction to Return Values

Return values allow functions to send data back to the part of the program that called them. This makes functions more versatile and reusable.

In this lesson, you will learn how to use return values effectively in Python functions.

What is a Return Value?

A return value is the output of a function. You can use the return keyword to send data back to the caller.

For example:

# Function with a return value
def add(a, b):
    return a + b

result = add(3, 5)
print(result)

Returning a Single Value

A function can return a single value using the return keyword:

# Returning a single value
def square(x):
    return x * x

result = square(4)
print(result)

Returning Multiple Values

You can return multiple values from a function as a tuple:

# Returning multiple values
def min_and_max(numbers):
    return min(numbers), max(numbers)

nums = [3, 5, 7, 2, 8]
minimum, maximum = min_and_max(nums)
print(minimum, maximum)

Using Return Values

Return values can be stored in variables or used directly in expressions:

# Using return values
def double(x):
    return x * 2

print(double(4) + double(5))

Returning None

If a function doesn’t have a return statement, it automatically returns None:

# Function returning None
def greet():
    print("Hello!")

result = greet()
print(result)

Practical Example

Here’s an example of a function that calculates the area of a rectangle:

# Practical example
def area_of_rectangle(length, width):
    return length * width

print(area_of_rectangle(5, 10))

def multiply(a, b):
    return a * b

result = multiply(3, 4)
print(result)

Common Mistakes with Return Values

Here are some common mistakes to avoid:

• Forgetting to use the return keyword in a function.
• Trying to use a function’s output without storing or using its return value.
• Returning incompatible types for expected use cases.

What Did We Learn?

In this lesson, you learned:

• What return values are and how to use them.
• How to return single or multiple values from a function.
• Practical applications of return values in Python.

Great job! Let’s move to the next lesson.