Python Functions

Last Updated: 01th September 2025

---

• Function is a block of code that performs a specific task.
• It only runs when it is called.
• Functions help you organize and re-use code.
• Function are Two Types:
  • User-Defined Functions: Created by you.
  • Built-in Functions: Part of the Python Standard Library.

Hinglish Tip 🗣: Function ko aise samjho—ek “machine” jisme input (parameters) jaata hai aur output (return value) milta hai. Ek baar banao, baar-baar use karo.

User-Defined Functions

Simple rules to define a function in Python:

• Functions blocks begin def followed by the function name and parentheses ().
• There is a body within every function that starts with a colon (:) and is indented.
• You can also place documentation before the body.
• They can have following types:
  • Non Parameterized Function
  • Parameterized Function
  • Default Parameterized Function
  • Positional Argument
  • Variable Length Argument
  • Keyword Argument
  • Return Function
  • Nested Function
  • Closure
  • Decorator
  • Recursion
  • Anonymous Function
  • Generator

Built-in Functions

Built-in functions are part of the Python Standard Library and you can use them without installing any additional packages. Some of them are: print(), len(), max(), min(), sum(), map(), filter(), etc.

---

---