9. Using the return statement in Python Functions

Quiz: 0/5

In Python, the return statement is used within functions to send back values to the caller. This is essential for modular and reusable code, as functions can compute results and return them to be used elsewhere in the program.

Purpose of the return statement

The return statement allows a function to output a value, which can then be used for further processing, calculations, or stored in a variable. When the return statement is executed, the function immediately stops, and control is returned to the point where the function was called.

Any code after the return statement will not be executed.

Example: Simple return

def add(a, b):
    result = a + b  # Calculate the sum
    return result  # Return the result to the caller

sum_value = add(3, 5)  # Calling the function and storing the result
print("The sum is:", sum_value)  # Output: The sum is: 8

Explanation:

• The add(a, b) function takes two parameters, a and b.
• It calculates their sum and uses the return statement to send this result back to the caller.
• The returned value is stored in sum_value, which is then printed.

Returning multiple values

Python allows functions to return multiple values at once using tuples. This is useful when you want to send back more than one result.

Example: Returning multiple values

def arithmetic_operations(x, y):
    addition = x + y
    subtraction = x - y
    return addition, subtraction  # Returning both values as a tuple

result_sum, result_difference = arithmetic_operations(10, 4)  # Unpacking the returned tuple
print("Sum:", result_sum)          # Output: Sum: 14
print("Difference:", result_difference)  # Output: Difference: 6

Explanation:

• The function arithmetic_operations(x, y) calculates both the sum and the difference of x and y.
• It returns these two values as a tuple.
• The caller unpacks the tuple into two variables, result_sum and result_difference, and prints them.

Implicit return

If a function does not include a return statement, Python automatically returns None. This behavior can be useful when you want to create a function that only performs an action without returning a value.

Example: Implicit return

def no_return():
    print("This function has no return statement.")

result = no_return()  # Calling the function
print(result)  # Output: None

Explanation:

• The function no_return() prints a message but does not have a return statement.
• By default, it returns None, which is captured by the variable result.

Return vs. Print

While the print() function outputs a value to the console, the return statement sends a value back to the caller for further use. It's important to know the difference because print() is used for displaying information, while return is used to provide output that can be used later in the program.

Example: Return vs Print

def double(x):
    print("Doubling:", x * 2)  # Prints the doubled value
    return x * 2  # Returns the doubled value

result = double(5)
print("Returned value:", result)  # Output: Returned value: 10

Explanation:

• The function double(x) both prints the doubled value and returns it.
• The return value is stored in result, while the print statement shows the value during the function's execution.

Summary

The return statement is fundamental in Python functions. It allows a function to output values that can be used elsewhere, making code more modular and reusable. Key points include:

• Single Return Value: A function can return a single value, such as the result of a calculation.
• Multiple Return Values: A function can return multiple values as a tuple.
• Implicit Return: If no return statement is provided, Python returns None by default.
• Difference with print(): The return statement provides values for further use, while print() is used for displaying information.