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Value-Returning Functions

A value returning function is a function that returns a value to the caller. The return value can be any Python object, such as a number, string, list, or dictionary.

To use a value returning function, you first need to define the function. The function definition includes the function name, the arguments, and the return statement.

Here is an example of a function that returns the sum of two numbers:

def sum(a, b):
    return a + b

To call the function, you use the function name followed by the arguments. For example, to call the sum function with the arguments 1 and 2, you would use the following code:

result = sum(1, 2)

The result variable will now contain the value of the function call, which is 3. You can print the value stored in the result variable to see the output.

print(result)  # Output: 3

Let's consider another example of a value-returning function that calculates and returns the factorial of a number. Please read the code carefully to understand how it works.

def factorial(number):
    fact = 1

    for i in range(1,number+1):
        fact = fact * i

    return fact

n = 5
f = factorial(n)
print('Factorial of', n,'is', f)

Output

Factorial of 5 is 120

Functions can be used to solve more difficult problems. Take a look at the given question, examine the solution code, and notice how functions help make the code reusable and modular, which is useful for tackling complex problems.

def factorial(n):
    fact = 1

    for i in range(1, n+1):
        fact = fact * i
    return fact

def equation(x, n):
    sum = 0
    
    for i in range(1, n+1):
        sum += x**i / factorial(i)   
    return sum
    
x = int(input('Enter the value of x: '))
n = int(input('Enter the number of terms: '))
result = equation(x, n)
print('The sum of series is', result)

Output

Enter the value of x: 2
Enter the number of terms: 4
The sum of series is 6.0

By defining the factorial and equation functions, the code breaks down the problem into smaller, focused tasks. The factorial function calculates the factorial of a number, and the equation function performs a specific equation to compute the sum of a series. The factorial function can be used whenever factorial calculations are needed.

Function Can Return Multiple Values in Python

In Python, functions are not limited to returning only a single value. They can also return multiple values, which can be useful in various scenarios.

def perform_math_operations(x, y):
  # Perform various mathematical operations on the given numbers
  addition = x + y
  subtraction = x - y
  multiplication = x * y
  division = x / y

  # Return the results as a tuple
  return addition, subtraction, multiplication, division

# Call the function to perform math operations
result_add, result_sub, result_mul, result_div = perform_math_operations(10, 5)

# Print the results
print("Addition:", result_add)
print("Subtraction:", result_sub)
print("Multiplication:", result_mul)
print("Division:", result_div)

The perform_math_operations() function calculates the addition, subtraction, multiplication, and division of two numbers x and y . It returns these results as a tuple. When calling the function and storing the returned values in separate variables, we can print and display the individual results.

Default Return Value in Functions - None

When working with functions in programming, it's important to understand the concept of the default return value. Let's consider the following function definition in Python:

def greet():
  print("Hello, world!")

In this function, there is no explicit return statement. When this function is called and assigned to a variable, like this:

result = greet()

The variable result will store the value returned by the function. However, since there is no return statement in the function, it automatically returns a special value called None . This means the function executes the code inside it, which is printing "Hello, world!" to the console, but it doesn't provide a specific value to be assigned to result .

To verify what value is stored in result , you can print it:

print(result)

The output will be None . This is because the function executed successfully but didn't explicitly return any value, resulting in the default return value of None .

To summarize, in Python, every function returns a value, even if you don't use the return statement. If a function lacks a return statement, it automatically returns None by default. Therefore, in the given example, when the greet() function is called and assigned to result , it stores None as the return value.

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