Return Values

Function Definitions

Python functions are defined using the def keyword, followed by the function name, parentheses (), and a colon :. The function body is indented.

def my_function(param1, param2):
  """This is a docstring describing the function."""
  # Function body
  result = param1 + param2
  return result

# Calling the function
output = my_function(5, 3) 
print(output)  # Output: 8

• Parameters and Arguments: param1 and param2 are parameters. When you call the function, you provide arguments (e.g., 5 and 3).

• Return Value: The return statement specifies the value the function sends back. If no return statement is present, the function implicitly returns None.

• Docstrings: The triple-quoted string ("""Docstring""") is a docstring. It’s used to document what the function does. It’s good practice to always include docstrings.

• Default Arguments: You can specify default values for parameters.

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

greet("Alice")  # Output: Hello, Alice!
greet("Bob", "Good morning")  # Output: Good morning, Bob!

• Variable Scope: Variables defined inside a function are local to that function. Variables defined outside are global. Variable Scope

• Keyword Arguments: Arguments can be passed by keyword (name=value), making the order less important.

def describe_pet(animal_type, pet_name):
    """Display information about a pet."""
    print(f"\nI have a {animal_type}.")
    print(f"My {animal_type}'s name is {pet_name.title()}.")

describe_pet(animal_type='hamster', pet_name='harry')

• Arbitrary Number of Arguments: Use *args for a variable number of positional arguments and **kwargs for a variable number of keyword arguments. Arbitrary Arguments

• Recursive Functions: Functions can call themselves. Recursion

• Lambda Functions: Anonymous, small functions defined using the lambda keyword. Lambda Functions

• Function Annotations: (Optional) Add type hints to parameters and return values for better readability and static analysis. Type Hinting