Functions in Python

Functions are reusable blocks of code that perform specific tasks. They help organize your code, improve readability, and promote modularity.

Defining Functions

Python

def function_name(parameters):

  """Function documentation"""

  # Function body

  return value

• function_name: The name of the function.

• parameters: Optional parameters that the function can accept.

• return value: Optional return value of the function.

Calling Functions

Python

result = function_name(arguments)

Example:

Python

def greet(name):

  """Greets the user with a personalized message."""

  print(f"Hello, {name}!")

greet("Alice")  # Output: Hello, Alice!

Parameters and Arguments

• Parameters: Variables defined within the function's parentheses.

• Arguments: Values passed to the function when it's called.

Return Values

• Functions can optionally return a value using the return statement.

• If a function doesn't have a return statement, it implicitly returns None.

Default Parameters

Python

def greet(name, greeting="Hello"):

  print(f"{greeting}, {name}!")

greet("Alice")  # Output: Hello, Alice!

greet("Bob", "Hi")  # Output: Hi, Bob!

Keyword Arguments

Python

def greet(name, greeting="Hello"):

  print(f"{greeting}, {name}!")

greet(name="Alice", greeting="Hi")

Variable-Length Arguments

• Arbitrary number of positional arguments:

Python

def greet(*names):

  for name in names:

    print(f"Hello, {name}!")

• Arbitrary number of keyword arguments:

Python

def greet(**kwargs):

  for key, value in kwargs.items():

    print(f"{key}: {value}")

Docstrings

• Use docstrings (triple-quoted strings) to document functions.

• They provide information about the function's purpose, parameters, and return value.

Best Practices:

• Use descriptive function names.

• Keep functions small and focused.

• Avoid excessive nesting.

• Write clear and concise docstrings.

By following these guidelines, you can write well-structured and maintainable functions in Python.