What Does Return Do in Python

When working with Python functions, you may have come across the “return” statement. But what exactly does it do? In this article, we’ll explore the purpose and functionality of the “return” statement in Python. We’ll delve into its various use cases and provide examples to help you understand how to leverage this statement effectively in your code.

Understanding the Basics

Python Function Without Return Statement

Every function in Python returns something. In cases where a function doesn’t have a return statement, it automatically returns None. Let’s consider the following example:

def print_something(s):
    print('Printing:', s)

output = print_something('Hi')
print(f"A function without a return statement returns {output}")

Output:

Printing: Hi
A function without a return statement returns None

Here, the print_something function doesn’t have a return statement. When we assign the function call to the output variable, it returns None.

Python Return Statement Example

The return statement is used to send a value or object back from a function. It allows us to perform operations within a function and then return the result to the caller. Consider the following example:

def add(x, y):
    result = x + y
    return result

output = add(5, 4)
print(f"The output of the add(5, 4) function is {output}")

Output:

The output of the add(5, 4) function is 9

In this example, the add function takes two arguments, x and y, and returns their sum.

Various Use Cases of the Return Statement

Returning Different Data Types

The return statement can handle various data types. It can return booleans, strings, tuples, and even functions.

Python Return Boolean

We can use the return statement to return boolean values from a function. Let’s consider the following example:

def bool_value(x):
    return bool(x)

print(f"The boolean value returned by bool_value(False) is {bool_value(False)}")
print(f"The boolean value returned by bool_value(True) is {bool_value(True)}")
print(f"The boolean value returned by bool_value('Python') is {bool_value('Python')}")

Output:

The boolean value returned by bool_value(False) is False
The boolean value returned by bool_value(True) is True
The boolean value returned by bool_value('Python') is True

In this example, the bool_value function takes an argument x and returns its boolean value using the bool() function.

Python Return String

We can also use the return statement to return string representations of objects. Let’s see an example:

def str_value(s):
    return str(s)

print(f"The string value returned by str_value(False) is {str_value(False)}")
print(f"The string value returned by str_value(True) is {str_value(True)}")
print(f"The string value returned by str_value(10) is {str_value(10)}")

Output:

The string value returned by str_value(False) is False
The string value returned by str_value(True) is True
The string value returned by str_value(10) is 10

In this example, the str_value function takes an argument s and returns its string representation using the str() function.

Python Return Tuple

Sometimes, we may want to convert multiple variables into a tuple and return it from a function. Let’s take a look at an example:

def create_tuple(*args):
    my_list = []
    for arg in args:
        my_list.append(arg * 10)
    return tuple(my_list)

t = create_tuple(1, 2, 3)
print(f"The tuple returned by create_tuple(1, 2, 3) is {t}")

Output:

The tuple returned by create_tuple(1, 2, 3) is (10, 20, 30)

In this example, the create_tuple function takes a variable number of arguments (*args), multiplies each argument by 10, stores the results in a list, and finally returns the list as a tuple using the tuple() function.

Returning Functions

In Python, functions can also be returned by another function. This concept is similar to Currying, which involves transforming a function that takes multiple arguments into a sequence of functions, each taking a single argument. Let’s see an example:

def get_cuboid_volume(h):
    def volume(l, b):
        return l * b * h
    return volume

volume_height_10 = get_cuboid_volume(10)
cuboid_volume = volume_height_10(5, 4)
print(f"The volume of the cuboid (5, 4, 10) is {cuboid_volume}")

cuboid_volume = volume_height_10(2, 4)
print(f"The volume of the cuboid (2, 4, 10) is {cuboid_volume}")

Output:

The volume of the cuboid (5, 4, 10) is 200
The volume of the cuboid (2, 4, 10) is 80

In this example, the get_cuboid_volume function returns the inner function volume, which calculates the volume of a cuboid based on its length (l), width (b), and the given height (h). By assigning volume_height_10 to get_cuboid_volume(10), we can now calculate the volume of different cuboids with a height of 10.

Returning Outer Functions

Similarly, we can also return a function that is defined outside of the current function. Let’s consider the following example:

def outer(x):
    return x * 10

def my_func():
    return outer

output_function = my_func()
print(type(output_function))
output = output_function(5)
print(f"The output is {output}")

Output:

<class 'function'>
The output is 50

In this example, the outer function is defined outside the my_func function. The my_func function returns the outer function, which is then assigned to output_function. We can then call output_function with an argument of 5, resulting in an output of 50.

Summary

In Python, the return statement plays a crucial role in functions. It allows us to send values or objects back from a function to the caller. We’ve explored its various use cases, including returning different data types, returning functions, and returning outer functions. By leveraging the return statement effectively, you can enhance the functionality and flexibility of your Python programs.

Remember, the return statement is a powerful tool in your programming arsenal, enabling you to create modular, reusable, and efficient code.

Thank you for reading, and happy coding!

FAQ

Can a Python function have multiple “return” statements?

Yes, a Python function can have multiple “return” statements. When a “return” statement is encountered in a function, the function execution is immediately terminated, and the value specified in the “return” statement is returned to the caller. Having multiple “return” statements allows for conditional branching and returning different values based on specific conditions within the function.

What happens if a Python function doesn’t have a “return” statement?

If a Python function doesn’t have a “return” statement, it automatically returns the value “None”. The “None” value signifies the absence of a specific value. It is commonly used to indicate that a function doesn’t produce any meaningful result or doesn’t return any specific value.

Can we use the “return” statement outside of a function in Python?

No, the “return” statement can only be used within the body of a function in Python. It is specifically used to exit a function and return a value to the caller. Trying to use the “return” statement outside of a function will result in a syntax error.

Is the “return” statement mandatory in Python functions?

No, the “return” statement is not mandatory in Python functions. It depends on the requirements of the function and the desired behavior. Some functions are designed to perform specific tasks without producing any output or returning a value. In such cases, omitting the “return” statement is perfectly valid.

Can the “return” statement be used with expressions in Python?

Yes, the “return” statement in Python can be used with expressions. An expression is evaluated, and the resulting value is returned by the function. This allows for more dynamic and flexible return values, as the expression can involve calculations, function calls, or other operations.

What are some common use cases for the “return” statement in Python?

The “return” statement in Python is widely used for various purposes, including:

• Returning values calculated within a function to the caller.
• Terminating the function execution prematurely based on certain conditions.
• Returning boolean values or string representations of objects.
• Returning tuples or other data structures containing multiple values.
• Returning functions themselves, enabling higher-order functions and function composition.

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