Python Programming | Aawiskar e-Siksha

Why Python?

Python is the world's most popular programming language for a reason. It reads almost like English, runs on everything, and is used everywhere from web servers to AI research to microcontrollers.

YOUR FIRST PYTHON PROGRAM

# This is a comment - Python ignores it
print("Hello, World!")
print("Welcome to Aawiskar e-Siksha!")

# Python does math too
print(2 + 2)         # Output: 4
print(10 ** 2)        # Output: 100 (exponent)
print(f"2 to the power 10 = {2**10}")  # f-strings!
        

🚀 Running Python: Download Python from python.org. Then open a terminal and type python filename.py to run your file. Or use an online editor like replit.com for instant testing — no installation!

Variables & Data Types

Variables are containers that store values. Python automatically figures out the type — no need to declare it like in C or Java!

ALL DATA TYPES WITH EXAMPLES

# INTEGER — whole numbers
age = 16
score = -42
big_num = 1_000_000  # underscores allowed for readability

# FLOAT — decimal numbers
pi = 3.14159
temperature = -12.5

# STRING — text (single or double quotes)
name = "Aawiskar"
city = 'Kathmandu'
multiline = """This is
a multiline
string."""

# BOOLEAN — True or False (capital T/F!)
is_student = True
has_wifi = False

# Check type of any variable
print(type(age))      # <class 'int'>
print(type(pi))       # <class 'float'>
print(type(name))     # <class 'str'>

# Type conversion
x = int("42")        # string → int
y = str(3.14)       # float → string
z = float("9.81")  # string → float

# String methods
greeting = "hello world"
print(greeting.upper())    # HELLO WORLD
print(greeting.title())    # Hello World
print(greeting.replace("world", "Nepal"))  # hello Nepal
print(len(greeting))       # 11
        

Control Flow

Control flow decides WHICH code runs based on conditions. Python uses indentation (spaces) instead of curly braces — this is mandatory, not optional!

# IF / ELIF / ELSE
marks = int(input("Enter your marks: "))

if marks >= 90:
    print("Grade: A+ — Outstanding!")
elif marks >= 75:
    print("Grade: A — Excellent!")
elif marks >= 60:
    print("Grade: B — Good")
elif marks >= 40:
    print("Grade: C — Pass")
else:
    print("Grade: F — Fail. Study harder!")

# Multiple conditions
age = 18
has_id = True

if age >= 18 and has_id:
    print("Access granted")
elif age >= 18 or has_id:
    print("Partial access")
else:
    print("Access denied")

# Ternary operator (one-liner)
status = "Adult" if age >= 18 else "Minor"
        

Loops & Iteration

Loops let you repeat code without rewriting it. Python has for loops (iterate over sequences) and while loops (repeat while a condition is true).

# FOR loop — iterating ranges and lists
for i in range(5):           # 0,1,2,3,4
    print(f"Step {i}")

for i in range(1, 11, 2):     # 1,3,5,7,9 (start,stop,step)
    print(i)

# Looping over strings
for letter in "Python":
    print(letter)

# WHILE loop — runs as long as condition is True
count = 0
while count < 5:
    print(f"Count: {count}")
    count += 1

# break and continue
for i in range(10):
    if i == 3:
        continue   # skip 3
    if i == 7:
        break      # stop at 7
    print(i)       # prints 0,1,2,4,5,6

# Nested loops — multiplication table
for i in range(1, 6):
    for j in range(1, 6):
        print(f"{i*j:4}", end="")
    print()
        

Functions & Modules

Functions are reusable blocks of code. Instead of writing the same logic multiple times, define it once and call it whenever needed.

# Basic function
def greet(name):
    return f"Namaste, {name}! Welcome to Aawiskar."

print(greet("Raju"))

# Default parameters
def power(base, exponent=2):
    return base ** exponent

print(power(5))       # 25 (uses default exponent=2)
print(power(2, 10))   # 1024

# Multiple return values
def min_max(numbers):
    return min(numbers), max(numbers)

low, high = min_max([3, 1, 9, 5, 2])
print(f"Min: {low}, Max: {high}")   # Min: 1, Max: 9

# Lambda — anonymous one-line function
square = lambda x: x ** 2
print(square(7))  # 49

# *args and **kwargs
def total(*numbers):        # accepts any number of args
    return sum(numbers)

print(total(1, 2, 3, 4, 5))  # 15
        

Lists, Tuples, Dicts & Sets

Python's built-in data structures are incredibly powerful. Master these four and you can represent almost any real-world data.

# LIST — ordered, mutable, allows duplicates
fruits = ["mango", "apple", "banana", "mango"]
fruits.append("cherry")
fruits.remove("apple")
print(fruits[0])         # mango (indexing)
print(fruits[-1])        # cherry (last item)
print(fruits[1:3])       # slicing

# List comprehension — Python's superpower!
squares = [x**2 for x in range(1, 11)]
evens = [x for x in range(20) if x % 2 == 0]

# DICTIONARY — key:value pairs, unordered
student = {
    "name": "Sita",
    "age": 17,
    "grades": [85, 92, 78],
    "enrolled": True
}
print(student["name"])             # Sita
student["age"] = 18               # update value
student["school"] = "Aawiskar"   # add new key

# Looping a dict
for key, value in student.items():
    print(f"{key}: {value}")

# SET — unique values, no duplicates
nums = {1, 2, 3, 2, 1}
print(nums)  # {1, 2, 3}
        

Object-Oriented Programming

OOP organizes code around "objects" — bundles of data (attributes) and behavior (methods). Everything in Python is already an object!

class Robot:
    # Class variable (shared by all instances)
    species = "Mechanical"
    
    # Constructor — called when object is created
    def __init__(self, name, battery=100):
        self.name = name         # instance variable
        self.battery = battery
        self.is_on = False
    
    def power_on(self):
        self.is_on = True
        print(f"{self.name} is now ON. Battery: {self.battery}%")
    
    def move(self, direction):
        if not self.is_on:
            print("Robot is off!")
            return
        self.battery -= 5
        print(f"{self.name} moved {direction}. Battery: {self.battery}%")
    
    # String representation
    def __str__(self):
        return f"Robot({self.name}, battery={self.battery}%)"

# Create instances
r1 = Robot("Robo-1")
r2 = Robot("Robo-2", battery=80)

r1.power_on()
r1.move("forward")
r1.move("left")
print(r1)  # Robot(Robo-1, battery=90%)

# INHERITANCE
class FlyingRobot(Robot):       # inherits from Robot
    def __init__(self, name):
        super().__init__(name)   # call parent constructor
        self.altitude = 0
    
    def fly(self, height):
        self.altitude = height
        self.battery -= 15
        print(f"{self.name} flying at {height}m!")
        

File Handling & Exceptions

Read, write, and process files. And handle errors gracefully with try/except so your program doesn't crash on unexpected input.

# Writing to a file
with open("data.txt", "w") as f:
    f.write("Aawiskar e-Siksha\n")
    f.write("Line 2\nLine 3\n")

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

# Read line by line
with open("data.txt") as f:
    for line in f:
        print(line.strip())

# TRY / EXCEPT — handle errors gracefully
try:
    num = int(input("Enter a number: "))
    result = 100 / num
    print(f"100 / {num} = {result}")
except ValueError:
    print("That's not a valid number!")
except ZeroDivisionError:
    print("Can't divide by zero!")
finally:
    print("Program finished.")  # always runs

# JSON — common file format for APIs
import json
data = {"name": "Sita", "score": 95}
with open("student.json", "w") as f:
    json.dump(data, f)
        

Project: Calculator App

Build a fully functional calculator in Python with a menu-driven interface. Combines everything: functions, loops, conditionals, and error handling.

def add(a, b): return a + b
def subtract(a, b): return a - b
def multiply(a, b): return a * b
def divide(a, b):
    if b == 0: raise ValueError("Cannot divide by zero!")
    return a / b

operations = {'+': add, '-': subtract, '*': multiply, '/': divide}

print("=== Aawiskar Calculator ===")
while True:
    try:
        a = float(input("\nEnter first number: "))
        op = input("Operator (+, -, *, /): ")
        b = float(input("Enter second number: "))
        
        if op not in operations:
            print("Invalid operator!")
            continue
        
        result = operations[op](a, b)
        print(f"Result: {a} {op} {b} = {result}")
        
        again = input("Calculate again? (y/n): ")
        if again.lower() != 'y': break
    except (ValueError, ZeroDivisionError) as e:
        print(f"Error: {e}")

print("Thanks for using Aawiskar Calculator!")
        

Project: Quiz Game

Build an interactive quiz with score tracking, random question order, and timing — all in under 50 lines of Python!

import random, time

questions = [
    {"q": "What does CPU stand for?",
     "options": ["A) Central Processing Unit", "B) Computer Power Unit", "C) Core Processing Universe"],
     "answer": "A"},
    {"q": "What voltage does Arduino Uno use?",
     "options": ["A) 3.3V", "B) 5V", "C) 12V"],
     "answer": "B"},
    {"q": "Which language does Arduino use?",
     "options": ["A) Python", "B) Java", "C) C++"],
     "answer": "C"},
]

random.shuffle(questions)
score = 0
start = time.time()

for i, q in enumerate(questions, 1):
    print(f"\nQ{i}: {q['q']}")
    for opt in q["options"]: print(opt)
    answer = input("Your answer (A/B/C): ").upper()
    if answer == q["answer"]:
        print("✓ Correct!"); score += 1
    else:
        print(f"✗ Wrong! Answer: {q['answer']}")

elapsed = round(time.time() - start, 1)
print(f"\n=== Score: {score}/{len(questions)} in {elapsed}s ===")
        

Project: Weather API

Fetch real weather data from the internet using Python's requests library. Calls the OpenWeatherMap API and displays current weather beautifully.

# pip install requests
import requests

API_KEY = "your_api_key_from_openweathermap.org"

def get_weather(city):
    url = f"https://api.openweathermap.org/data/2.5/weather"
    params = {"q": city, "appid": API_KEY, "units": "metric"}
    
    try:
        response = requests.get(url, params=params)
        response.raise_for_status()
        data = response.json()
        
        print(f"\n🌤️  Weather in {data['name']}, {data['sys']['country']}")
        print(f"Temperature: {data['main']['temp']}°C")
        print(f"Feels like: {data['main']['feels_like']}°C")
        print(f"Humidity: {data['main']['humidity']}%")
        print(f"Condition: {data['weather'][0]['description'].title()}")
        print(f"Wind Speed: {data['wind']['speed']} m/s")
    except requests.exceptions.HTTPError:
        print(f"City '{city}' not found!")
    except requests.exceptions.ConnectionError:
        print("No internet connection!")

city = input("Enter city name: ")
get_weather(city)
# Try: Kathmandu, London, Tokyo, New York
        

🔑 Getting an API Key: Sign up free at openweathermap.org, go to API Keys section, and copy your key. Free tier allows 1000 calls/day — more than enough for learning!