Python

Important Statements

Defining a Function

Use the def keyword to define a function.

def function_name(parameter1, parameter2="default_value", *args, **kwargs):
    # Code block inside the function
    statement_a
    statement_b
    # ...
    # Optional: return value
    # return result

• def: Keyword to start a function definition.
• function_name: A descriptive name for the function.
• (parameter1, parameter2="default_value", ...): Optional list of parameters.
  • Parameters can have default values using =. Parameters with default values must come after parameters without default values.
  • args: Gathers any extra positional arguments into a tuple.
  • *kwargs: Gathers any extra keyword arguments into a dictionary.
• :: Marks the end of the function header.
• The indented block is the function body, containing the code that runs when the function is called.

Calling a Function

To execute the code inside a function, you call it by its name followed by parentheses (). If the function expects parameters, you provide arguments.

# Calling a function with no parameters
function_name()

# Calling a function with positional arguments
function_name(argument1, argument2)

# Calling a function using keyword arguments (order doesn't matter)
function_name(parameter2=argument2, parameter1=argument1)
function_name(parameter1=value1) # Using default for parameter2

# Mixing positional and keyword arguments (positional must come first)
function_name(argument1, parameter2=argument2)

# Calling a function that returns a value
result = function_name(argument1)

• argument1, argument2: The actual values passed to the function's parameters.
• Positional Arguments: Arguments passed based on their position in the function call, matching the order of parameters in the definition.
• Keyword Arguments: Arguments passed using the parameter name followed by =. This allows you to pass arguments in any order and makes the call clearer.

The return Statement

Used inside a function to exit the function and optionally send a value back to the caller.

def add_numbers(a, b):
    sum_result = a + b
    return sum_result # Return the calculated sum

# Call the function and store the returned value
total = add_numbers(5, 3) # total will be 8

• return: Keyword to exit the function.