Functions

In Python, def is a keyword used to define functions. Functions are blocks of reusable code that perform a specific task. Defining functions allows you to break down your code into smaller, more manageable pieces and promote code reusability.

Basic Syntax:

def function_name(parameter1, parameter2, ...):
    # Function body
    # Code statements
    # Return statement (optional)

Let’s break down each part of the function definition:

• def: It is the keyword used to start the function definition.
• function_name: It is the name you choose for your function. The name should be descriptive and follow the Python naming conventions.
• (parameter1, parameter2, ...): These are optional parameters or arguments that the function can accept. Parameters are like placeholders that can be used within the function to work with data.
• :: It denotes the end of the function header and the start of the function body.
• Function body: It consists of the code statements that define what the function does. This block of code is indented under the def statement.
• Return statement (optional): It is used to specify the value that the function should return. If no return statement is present, the function returns None by default.

Here’s an example of a simple function that calculates the square of a number:

def square(number):
    result = number ** 2
    return result

Now, you can call the square function and pass a number as an argument to get the square of that number:

result = square(5)
print(result) # Output: 25

In this example, the function square takes a parameter number, calculates the square of the number using the exponentiation operator **, and returns the result. The returned value is then assigned to the variable result and printed to the console.

You can define functions with multiple parameters, default parameter values, variable-length arguments, and more, depending on your specific requirements.