Functions, Classes, and Patterns

Write reusable code with functions, classes, decorators, and functional tools like map/filter and lambdas. These patterns teach you how to structure programs for clarity and extensibility.

Try Python Compiler
Popular Examples
Python "Hello, World!" Program Python Variables and Types Python Arithmetic Operations Python Strings Basics Python Lists and Loops Python Dictionaries Python Functions Python Classes Python Exceptions Python File I/O Python Generators Python Decorators Python Lambda, map, filter Python Program to Add Two Numbers Python Program to Find the Square Root Python Program to Calculate the Area of a Triangle Python Program to Solve Quadratic Equation Python Program to Swap Two Variables Python Program to Generate a Random Number Python Program to Convert Kilometers to Miles Python Program to Convert Celsius To Fahrenheit Python Program to Check if a Number is Positive, Negative or 0 Python Program to Check if a Number is Odd or Even Python Program to Check Leap Year Python Program to Find the Largest Among Three Numbers Python Program to Check Prime Number Python Program to Print all Prime Numbers in an Interval Python Program to Find the Factorial of a Number Python Program to Display the multiplication Table Python Program to Print the Fibonacci sequence Python Program to Check Armstrong Number Python Program to Find Armstrong Number in an Interval Python Program to Find the Sum of Natural Numbers Python Program to Display Powers of 2 Using Anonymous Function Python Program to Find Numbers Divisible by Another Number Python Program to Convert Decimal to Binary, Octal and Hexadecimal Python Program to Find ASCII Value of Character Python Program to Find HCF or GCD Python Program to Find LCM Python Program to Find the Factors of a Number Python Program to Make a Simple Calculator Python Program to Shuffle Deck of Cards Python Program to Display Calendar Python Program to Display Fibonacci Sequence Using Recursion Python Program to Find Sum of Natural Numbers Using Recursion Python Program to Find Factorial of Number Using Recursion Python Program to Convert Decimal to Binary Using Recursion Python Program to Add Two Matrices Python Program to Transpose a Matrix Python Program to Multiply Two Matrices Python Program to Check Whether a String is Palindrome or Not Python Program to Remove Punctuations From a String Python Program to Sort Words in Alphabetic Order Python Program to Illustrate Different Set Operations Python Program to Count the Number of Each Vowel Python Program to Merge Mails Python Program to Find the Size (Resolution) of an Image Python Program to Find Hash of File Python Program to Create Pyramid Patterns Python Program to Merge Two Dictionaries Python Program to Safely Create a Nested Directory Python Program to Access Index of a List Using for Loop Python Program to Flatten a Nested List Python Program to Slice Lists Python Program to Iterate Over Dictionaries Using for Loop Python Program to Sort a Dictionary by Value Python Program to Check If a List is Empty Python Program to Catch Multiple Exceptions in One Line Python Program to Copy a File Python Program to Concatenate Two Lists Python Program to Check if a Key is Already Present in a Dictionary Python Program to Split a List Into Evenly Sized Chunks Python Program to Parse a String to a Float or Int Python Program to Print Colored Text to the Terminal Python Program to Convert String to Datetime Python Program to Get the Last Element of the List Python Program to Get a Substring of a String Python Program to Print Output Without a Newline Python Program Read a File Line by Line Into a List Python Program to Randomly Select an Element From the List Python Program to Check If a String Is a Number (Float) Python Program to Count the Occurrence of an Item in a List Python Program to Append to a File Python Program to Delete an Element From a Dictionary Python Program to Create a Long Multiline String Python Program to Extract Extension From the File Name Python Program to Measure the Elapsed Time in Python Python Program to Get the Class Name of an Instance Python Program to Convert Two Lists Into a Dictionary Python Program to Differentiate Between type() and isinstance() Python Program to Trim Whitespace From a String Python Program to Get the File Name From the File Path Python Program to Represent enum Python Program to Return Multiple Values From a Function Python Program to Get Line Count of a File Python Program to Find All File with .txt Extension Present Inside a Directory Python Program to Get File Creation and Modification Date Python Program to Get the Full Path of the Current Working Directory Python Program to Iterate Through Two Lists in Parallel Python Program to Check the File Size Python Program to Reverse a Number Python Program to Compute the Power of a Number Python Program to Count the Number of Digits Present In a Number Python Program to Check If Two Strings are Anagram Python Program to Capitalize the First Character of a String Python Program to Compute all the Permutation of the String Python Program to Create a Countdown Timer Python Program to Count the Number of Occurrence of a Character in String Python Program to Remove Duplicate Element From a List Python Program to Convert Bytes to a String
More code tools Python Compiler JavaScript Compiler All Code Editors

Python Lambda, map, filter

Use lambda with map and filter.

nums = [1, 2, 3, 4, 5]
squares = list(map(lambda x: x * x, nums))
evens = list(filter(lambda x: x % 2 == 0, nums))
print(squares)
print(evens)

Output

[1, 4, 9, 16, 25]
[2, 4]

Python Functions

Define and call functions with default and keyword arguments.

def greet(name: str, punctuation: str = "!") -> str:
    return f"Hello, {name}{punctuation}"

print(greet("Ann"))
print(greet("Bob", punctuation="."))

Output

Hello, Ann!
Hello, Bob.

Python Classes

Create a simple class with methods and attributes.

class Counter:
    def __init__(self):
        self.value = 0
    def increment(self):
        self.value += 1
    def get(self):
        return self.value

c = Counter()
c.increment()
print(c.get())

Output

1

Python Decorators

Wrap functions to add behavior.

def log(fn):
    def wrapper(*args, **kwargs):
        print("calling", fn.__name__)
        return fn(*args, **kwargs)
    return wrapper

@log
def add(a, b):
    return a + b

print(add(2, 3))

Output

calling add
5

Python Program to Differentiate Between type() and isinstance()

Shows difference.

class B: pass
class C(B): pass
obj = C()
print(type(obj) is B)
print(isinstance(obj, B))

Output

False
True

Python Program to Represent enum

Uses Enum.

from enum import Enum
class Color(Enum):
    RED = 1
    GREEN = 2
print(Color.RED.name, Color.RED.value)

Output

RED 1

Python Program to Return Multiple Values From a Function

Returns a tuple.

def stats(a, b):
    return a+b, a*b
print(stats(3,4))

Output

(7, 12)

Python Strings Basics

Concatenate, format, and slice strings.

s = "Hello, Python"
print(s.lower())
print(s.upper())
print(s[0:5])
print(f"Length: {len(s)}")

Output

hello, python
HELLO, PYTHON
Hello
Length: 13

Python Program to Find the Square Root

Computes square root using math module.

import math
print(math.sqrt(16))

Output

4.0

Keep Practicing

Use the online Python compiler to run examples and test variations. Reinforce learning by building small scripts for each topic.

FAQ

You can use the online Python compiler linked above to run examples instantly. For larger projects, install Python locally.

Yes. Examples cover variables, control flow, data structures, functions, classes, and file I/O—ideal for beginners.

Yes. The programs are tested and produce consistent output across major platforms.

Learn Python by Practicing Examples

Hands-on practice is the fastest way to understand Python. Each example focuses on a single concept—from variables, strings, lists, and dictionaries to loops, functions, classes, exceptions, and file I/O. Modify examples, add new functions, and see how clean design leads to readable, maintainable code.

Use our tools to deepen learning: the Python Compiler to run snippets, and the Python Tutorial for structured lessons.

Beginner-Friendly

Start with variables, operators, and control flow. Build confidence with small, readable programs.

Practical Patterns

Practice lists, dicts, comprehensions, functions, classes, exceptions, and file handling.

Grow Skills

Explore generators and decorators to write expressive, reusable code.