Function in Python

A function in Python is a reusable block of organized, self-contained code that is written to perform a specific task when it is called.

• Instead of writing the same code multiple times, we can define it once inside a function and reuse it as needed.

• This helps reduce redundancy and enhances readability and modularity in programs.

• It helps in organizing code, reducing repetition, and making programs easier to understand and maintain.

Example: Here, greet() is a function that, when called, prints “Hello, Python!”.

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

Types of Functions in Python:

Python supports two main types of functions:

1. Built-in Functions:
   • These are pre-defined in Python (e.g., print(), len(), range()).

2. User-defined Functions:
   • Functions created by the programmer using the def keyword.

Other Classifications Based on Use:

• Function with No Arguments and No Return Value
• Function with Arguments but No Return Value
• Function with Arguments and Return Value
• Lambda Functions – Anonymous, one-line functions.
• Recursive Functions – A function that calls itself.

Benefits of Using Functions:

• Code Reusability – Define once, use multiple times.
• Modularity – Break down complex problems into smaller parts.
• Improved Readability – Logical structure makes code easier to follow.
• Debugging Made Easier – Isolating code in functions helps in identifying bugs.
• Efficient Collaboration – Teams can work on different functions independently.

Basic Examples:

1.) Function without Parameters:

def say_hello():
    print("Hello!")
say_hello()

2.) Function with Parameters:

def greet(name):
    print(f"Hello, {name}!")
greet("Alice")

3.) Function with Return Value:

def add(x, y):
    return x + y
result = add(5, 3)
print(result)