Python Cheat Sheet — Complete Syntax Reference and Programming Examples

This Python Cheat Sheet is your quick reference guide for writing efficient Python code. Whether you’re preparing for coding interviews, building web apps, or automating tasks, this page helps you recall syntax, functions, and examples instantly.

Introduction to Python Programming

Python is a high-level, interpreted language famous for its simplicity, readability, and versatility. It supports multiple paradigms like object-oriented, functional, and procedural programming.

Example: Basic Hello World Program

print("Hello, World!")

Output:

Hello, World!

Python Syntax and Variables

Python uses indentation (4 spaces) instead of braces {} for code blocks.

name = "Alice"
age = 25
height = 5.6
is_student = True

print(name, age, height, is_student)

Python Data Types and Type Conversion

Type Conversion Example:

x = "123"
y = int(x)
print(y + 10)

Python Operators Reference Table

Python Conditional Statements

age = 20

if age >= 18:
    print("Adult")
elif age > 13:
    print("Teenager")
else:
    print("Child")

Python Loops and Iteration

For Loop Example

for i in range(5):
    print("Number:", i)

While Loop Example

count = 0
while count < 3:
    print("Count:", count)
    count += 1

Loop Control Statements

• break → exits loop
• continue → skips iteration
• pass → does nothing (placeholder)

Python Functions and Scope

def greet(name="User"):
    """Simple greeting function"""
    return f"Hello, {name}!"

print(greet("Alice"))

Lambda Functions

square = lambda x: x * x
print(square(4))

Python Lists, Tuples, and Dictionaries — Data Structures Quick Reference

Lists

fruits = ["apple", "banana", "cherry"]
fruits.append("mango")
print(fruits[1])  # banana

Tuples

colors = ("red", "green", "blue")
print(colors[0])

Dictionaries

student = {"name": "John", "age": 20, "marks": 88}
print(student["name"])

Python String Handling and Formatting

text = "Python Cheat Sheet"
print(text.lower())
print(text.upper())
print(text.replace("Python", "Awesome Python"))
print(f"{text} is easy to learn!")

Python File Handling Examples

# Write to a file
with open("data.txt", "w") as f:
    f.write("Learning Python is fun!")

# Read a file
with open("data.txt", "r") as f:
    content = f.read()
    print(content)

Python Exception Handling

try:
    num = int(input("Enter a number: "))
    print(10 / num)
except ValueError:
    print("Invalid input!")
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Done.")

Python Classes and Object-Oriented Programming

class Car:
    def __init__(self, brand, color):
        self.brand = brand
        self.color = color

    def drive(self):
        print(f"{self.brand} is driving...")

car1 = Car("Tesla", "Red")
car1.drive()

Python Modules and Imports

import math
print(math.sqrt(16))

Custom module:

# mymodule.py
def add(a, b):
    return a + b

# main.py
from mymodule import add
print(add(5, 7))

Python List Comprehension and Generator Expressions

squares = [x * x for x in range(1, 6)]
print(squares)

even_numbers = (x for x in range(10) if x % 2 == 0)
for num in even_numbers:
    print(num)

Python Useful Built-in Functions

Python Packages and Virtual Environments

pip install requests
pip list

To create a virtual environment:

python -m venv myenv
source myenv/bin/activate  # (Linux/Mac)
myenv\Scripts\activate     # (Windows)

Python File and Directory Operations

import os

os.mkdir("demo_folder")
os.rename("demo_folder", "new_folder")
print(os.getcwd())

Python Regular Expressions (re module)

import re
text = "Contact: hello@phponline.in"
result = re.search(r"\w+@\w+\.\w+", text)
print(result.group())

Python Cheat Sheet Summary Table

Python cheat sheet, Python syntax reference, Python programming examples, Python basics tutorial, Python functions and loops, Python data structures guide, Python file handling, Python OOP, Python shortcuts

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Frequently Asked Questions (FAQ)

Q1. Is Python beginner-friendly?
Yes. Python is ideal for beginners because of its clean syntax and readability.

Q2. How can I run a Python program?
Save the file as program.py and run python program.py in the terminal.

Q3. What’s the difference between list and tuple?
Lists are mutable (can be changed); tuples are immutable (fixed).

Q4. What is PEP8?
PEP8 is the official Python style guide. It defines code formatting standards.

Q5. How do I comment in Python?
Use # for single-line comments and triple quotes ('''...''') for multi-line.