Python Functions

• What is a Function in Python?

  • A function is a reusable block of code that performs a specific task.
  • Define the function once.
  • Call it whenever you need it.
     

• Syntax

def function_name():
   # Code to execute

• def → Keyword used to define a function.
• function_name → Name of the function.
• () → Parentheses (can contain parameters).
• : → Starts the function body.
• Indented code → The statements that belong to the function.

def greet():
   print("Hello, Welcome to Python!")
   
greet()

Output

Hello, Welcome to Python!

• Function with Parameters

  • A parameter is a variable that receives a value when the function is called.

def greet(name):
   print("Hello", name)
   
greet("Alice")
greet("Bob")

Output

Hello Alice
Hello Bob

Here:

• name is the parameter.
• "Alice" and "Bob" are the arguments.

Returning a Value

• The return statement sends a value back to the caller.

def add(a, b):
   return a + b
   
result = add(5, 7)

print(result)

Output

12

• Type Hints in function

  • Type hints tell Python (and other developers) what type of data a function expects and what type it returns.
     

• Syntax

def function_name(parameter: data_type) -> return_type:
   ...

• : → Specifies the parameter type.
• -> → Specifies the return type.

Type Hints

Real-Life Analogy

Think of a TV remote:

• 📺 Press the Power button → TV turns on.
• 🔊 Press the Volume Up button → Volume increases.
• 🔇 Press the Mute button → TV is muted.

Each button performs a specific task. In Python, each function performs a specific task in the same way.