↑ Python

---

Python - Functions

Functions are blocks of code with a defined task. They allow better organisation, avoid repetition and provide better readability.

def function_name(param1, param2):
  # code to execute
  return value

function_name(arg1, arg2)

Parameters / arguments and return

• parameters: variables that are passed to the function, they are defined in the declaration of the function.
• arguments: values that are passed when calling the function.
• return: the result sent back by the function after its execution, if not defined the function will return None by default.

def addition(a, b):
  return a + b

result = addition(3, 5)

Variables reach (scope)

The scope of a variable determines where it can be used, variables defined inside a function have a local scope, they can be accessed only inside this function.

Local scope

def my_function():
  x = 10 # local variable
  print(x)

my_function() # Displays 10
print(x) # Error: x is undefined

Global scope

x = 10 # global variable

def my_function():
  global x # mark that we want to use and edit the global variable
  x = 20
  print(x)

my_function() # Displays 20
print(x) # Displays 20 too because the global variable was edited

Default values for parameters

If you define a default value for a parameter and no argument is used when calling this function, the default value will be used instead.

def hello(word="world")
  print(f"Hello {word}!")

hello("Joe") # "Hello Joe!"
hello() # "Hello world!"