Functions:

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Functions in Python

Functions are blocks of reusable code in Python. They help in organizing code, avoiding repetition, and improving code readability. This page covers the types of functions based on arguments and return values, as well as the different types of arguments that functions can accept.

What is Function Definition?

A function definition is the process of specifying the structure and behavior of a function. It includes the function's name, parameters, and the block of code that defines what the function does. The syntax is:

Example:

Types of Functions Based on Arguments and Return Values

• No Arguments and No Return Value

  These functions neither take any input arguments nor return any value.

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




• Arguments but No Return Value

  These functions take input arguments but do not return any value.

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




• No Arguments but Returns a Value

  These functions do not take any input arguments but return a value.

  def get_number(): return 42 number = get_number() print(number)




• Arguments and Return Value

  These functions take input arguments and also return a value.

  def add(a, b): return a + b result = add(5, 3) print(result)

Types of Arguments in Python Functions

• Positional Arguments

  Arguments passed to the function in the correct positional order.

  def add(a, b): return a + b result = add(2, 3)




• Keyword Arguments

  Arguments passed to the function by explicitly stating the parameter names.

  def greet(name, message): print(f"{message}, {name}!") greet(name="Bob", message="Good morning")




• Default Arguments

  Arguments that assume a default value if a value is not provided during the function call.

  def greet(name, message="Hello"): print(f"{message}, {name}!") greet("Alice") greet("Bob", "Good evening")




• Variable-Length Arguments

  Functions that accept a variable number of arguments. These can be of two types:

  • *args

    Allows a function to accept any number of positional arguments.

    def sum_all(*args): return sum(args) print(sum_all(1, 2, 3, 4))
  
  

  • **kwargs

    Allows a function to accept any number of keyword arguments.

    def print_details(**kwargs): for key, value in kwargs.items(): print(f"{key}: {value}") print_details(name="Alice", age=30, job="Developer")

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