🐍 Function

function

Good to know

⭐️ Functions let you group reusable logic into named blocks. Use def to define a function, and return to send a value back. Functions can take parameters, have default values, and accept variable numbers of arguments.

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Basic Function

Defines a function and calls it.

def say_hi():
    print("Hello User")
 
say_hi()

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Parameters

Function With Parameters

Parameters receive values when the function is called. Inside classes, you might wanna use: the self parameter

def say_hi(name):
    print("Hello " + name)
 
say_hi("Alain")

Function With Multiple Parameters

def say_hi(name, age):
    print("Hello " + name + " you are " + str(age))
 
say_hi("Alain", 33)

Default Parameters

Useful when callers may omit some arguments.

def greet(name="User"):
    print("Hello", name)
 
greet()          # Hello User
greet("Alain")   # Hello Alain

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Keyword Arguments

Call a function using name=value for flexibility.

def say_hi(name, age):
    print(name, "is", age)
 
say_hi(age=30, name="Alain")

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Variable-Length Arguments (args)

If the number of arguments can change, use args.

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Docstrings (Function Documentation)

Use triple quotes to describe what your function does. This text will be shown, when hovered with the mouse over the function.

def add(a, b):
    """Returns the sum of two numbers."""
    return a + b

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Returning Values

return sends a value back to the caller.

def cube(num):
    return num * num * num
 
result = cube(3)
print(result)   # 27

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Lambda Functions (Small Anonymous Functions)

Useful for short one-line operations.

square = lambda x: x * x # lambda parameter: logic
print(square(5))   # 25

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Functions Calling Other Functions

def greet():
    print("Hello!")
 
def welcome_user():
    greet()
    print("Welcome!")
 
welcome_user()