Python Tutorial

Python Tutorial for Beginners

Python is a high-level, interpreted, and dynamically typed programming language that is widely used for web development, data science, automation, AI, and more.

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1. Installing Python

Download Python from python.org and install it.

Check if Python is installed by running:

python --version

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2. Writing and Running Python Code

You can run Python code in:

• Interactive Mode: Using the Python interpreter (python in terminal).
• Script Mode: Writing a .py file and running it with python filename.py.

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3. Python Syntax

Hello World Program

print("Hello, World!")

Python Indentation (No {})

if True:
    print("Python uses indentation")  # Correct

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4. Python Variables and Data Types

x = 10       # Integer
y = 3.14     # Float
name = "Alice"  # String
is_valid = True  # Boolean

Check data type:

print(type(x))  # Output: <class 'int'>

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5. Taking User Input

name = input("Enter your name: ")
print("Hello,", name)

✅ input() always returns a string, so convert it if needed:

age = int(input("Enter your age: "))

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6. Python Operators

Arithmetic Operators

a = 10
b = 5
print(a + b)  # Addition: 15
print(a / b)  # Division: 2.0
print(a ** b) # Exponentiation: 100000

Comparison Operators

print(10 > 5)  # True
print(10 == 5)  # False

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7. Python Conditional Statements

age = 18

if age >= 18:
    print("You are an adult.")
elif age == 17:
    print("Almost an adult.")
else:
    print("You are a minor.")

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8. Python Loops

(a) for Loop

for i in range(5):  # Loops from 0 to 4
    print(i)

(b) while Loop

count = 0
while count < 5:
    print(count)
    count += 1

✅ Use break to exit and continue to skip an iteration.

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9. Python Functions

def greet(name):
    print(f"Hello, {name}!")

greet("Alice")  # Output: Hello, Alice!

✅ Functions make code modular and reusable.

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10. Python Lists

Lists store multiple values.

fruits = ["apple", "banana", "cherry"]
print(fruits[0])  # Output: apple
fruits.append("orange")  # Add an element
print(fruits)

✅ Lists are mutable (modifiable).

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11. Python Tuples

Tuples are immutable (cannot be modified).

coordinates = (10, 20)
print(coordinates[0])  # Output: 10

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12. Python Dictionaries (dict)

Dictionaries store key-value pairs.

person = {"name": "Alice", "age": 25}
print(person["name"])  # Output: Alice
person["city"] = "New York"  # Add new key-value pair

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13. Python File Handling

(a) Writing to a File

with open("test.txt", "w") as file:
    file.write("Hello, Python!")

(b) Reading a File

with open("test.txt", "r") as file:
    print(file.read())

✅ Use with open() to avoid closing files manually.

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14. Exception Handling (try-except)

Handle errors gracefully:

try:
    x = 10 / 0  # Error (division by zero)
except ZeroDivisionError:
    print("Cannot divide by zero!")

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15. Python Object-Oriented Programming (OOP)

(a) Defining a Class

class Person:
    def __init__(self, name, age):  # Constructor
        self.name = name
        self.age = age

    def greet(self):
        print(f"Hello, my name is {self.name}")

p = Person("Alice", 25)
p.greet()  # Output: Hello, my name is Alice

(b) Inheritance

class Student(Person):
    def __init__(self, name, age, grade):
        super().__init__(name, age)
        self.grade = grade

s = Student("Bob", 20, "A")
print(s.name, s.grade)

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16. Python Modules

Python has built-in and external modules.

(a) Importing a Built-in Module

import math
print(math.sqrt(16))  # Output: 4.0

(b) Creating Your Own Module (my_module.py)

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

Use in another script:

import my_module
print(my_module.add(2, 3))  # Output: 5

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17. Python JSON Handling

Working with JSON data:

import json

person = '{"name": "Alice", "age": 25}'
data = json.loads(person)  # Convert JSON string to dictionary
print(data["name"])  # Output: Alice

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18. Python Regular Expressions (Regex)

import re

text = "My email is example@email.com"
match = re.search(r"\S+@\S+", text)
print(match.group())  # Output: example@email.com

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19. Python Date and Time

import datetime

now = datetime.datetime.now()
print(now.strftime("%Y-%m-%d %H:%M:%S"))  # Formatted output

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20. Python Web Scraping (BeautifulSoup Example)

from bs4 import BeautifulSoup
import requests

url = "https://example.com"
response = requests.get(url)
soup = BeautifulSoup(response.text, "html.parser")
print(soup.title.text)  # Get the page title

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Conclusion

🚀 Python is easy to learn and powerful!

• ✅ Use variables, functions, loops, and conditions for basic programs.
• ✅ Lists, tuples, dictionaries store data efficiently.
• ✅ OOP, file handling, and modules make Python powerful.
• ✅ Use libraries like math, json, re, datetime, and BeautifulSoup for advanced tasks.

Start practicing Python and build your own projects!

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