Python • Introduction

Python Introduction & Fundamentals

Welcome to Python! Learn what makes Python so popular, master the fundamentals, and build a strong foundation with practical examples.

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What is Python?

High-level, interpreted programming language created by Guido van Rossum in 1991

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Most Popular

Used by beginners and experts in data science, AI, web dev, and more

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Simple & Clean

Readable syntax that looks like English, perfect for beginners

1. Python Variables

A variable is a name that stores a value. Python figures out the type automatically.

variables.py

# School-themed variables
student_name = "Aarav"      # string
grade = 8                   # integer
average_marks = 84.33       # float
is_passed = True            # boolean

print(student_name, "is in grade", grade)

Rules:

Names can contain letters, numbers, underscores (_), but cannot start with a number.
Case‑sensitive (name ≠ Name).
Use meaningful names for readability.

2. Python Data Types

Python has several built‑in data types. The most common ones are:

Data Type	Example	Description
`int`	`8, -3, 0`	Whole numbers
`float`	`3.14, 84.5`	Decimal numbers
`str`	`"Hello"`	Text, wrapped in quotes
`bool`	`True, False`	Logical values
`NoneType`	`None`	Represents "nothing" or empty

Check a type with type() (see later).

3. print() Function

The print() function displays output on the screen.

print_examples.py

print("Hello, World!")
print("Aarav", "Grade", 8)
print("Maths", "Science", sep=" | ")
print("Welcome", end=" --> ")
print("Have a nice day!")

Hello, World! Aarav Grade 8 Maths | Science Welcome --> Have a nice day!

4. String Formatting (f‑strings)

Python's modern way is f‑strings (Python 3.6+).

fstring_example.py

name = "Aarav"
marks = 84.56
print(f"{name} scored {marks} marks.")
print(f"Rounded: {marks:.1f}")

5. input() Function

input() waits for user input and returns a string. Convert to numbers when needed.

user_input.py

subject = input("What is your favorite subject? ")
print("Great choice! You enjoy", subject)
maths = int(input("Enter Maths marks: "))
english = float(input("Enter English marks: "))
total = maths + english
print("Total marks:", total)

⚠️ Important: Always convert input() with int() or float() for calculations.

6. type() Function

type() returns the data type – great for debugging.

type_check.py

name = "Aarav"
grade = 8
average = 84.33
passed = True
print(type(name))   # 
print(type(grade))  # 
print(type(average))# 
print(type(passed)) #

Quick Practice: Putting It All Together

mini_project.py

student = input("Enter student name: ")
grade = int(input("Enter grade level: "))
marks = float(input("Enter average marks: "))
print("\n--- Student Summary ---")
print(f"Name       : {student}")
print(f"Grade      : {grade}")
print(f"Marks      : {marks:.2f}")
print(f"Data types : {type(student)}, {type(grade)}, {type(marks)}")

Enter student name: Priya Enter grade level: 7 Enter average marks: 91.5 --- Student Summary --- Name : Priya Grade : 7 Marks : 91.50 Data types : <class 'str'>, <class 'int'>, <class 'float'>

Practice Problems

Apply what you've learned with these beginner and intermediate problems.

🔰 Beginner Level

1. Greeting Generator

Problem: Ask for first name and age, then print a personalized greeting.

first_name = input("Enter your first name: ")
age = int(input("Enter your age: "))
print(f"Hello {first_name}, you are {age} years old!")

2. Simple Interest Calculator

Problem: Accept principal, rate, and time. Calculate SI = (P*R*T)/100.

principal = float(input("Enter principal amount (₹): "))
rate = float(input("Enter rate of interest (%): "))
time = float(input("Enter time (years): "))
simple_interest = (principal * rate * time) / 100
print(f"Simple Interest: ₹{simple_interest:.2f}")

3. Temperature Converter (Celsius → Fahrenheit)

Problem: Convert Celsius to Fahrenheit: F = (C × 9/5) + 32.

celsius = float(input("Enter temperature in Celsius: "))
fahrenheit = (celsius * 9/5) + 32
print(f"{celsius}°C is equal to {fahrenheit:.1f}°F")

⚡ Intermediate Level

4. Swap Two Variables Without Third Variable

Problem: Swap two numbers using tuple unpacking.

a = int(input("Enter first number (a): "))
b = int(input("Enter second number (b): "))
print(f"Before swap: a = {a}, b = {b}")
a, b = b, a
print(f"After swap: a = {a}, b = {b}")

Unsolved Exercises

Test yourself! No solutions here—just the problem statement.

🔰 Beginner Level

1. Rectangle Area Calculator

Problem: Ask for length and width, compute area, print rounded to 2 decimals.

Write your code here – solution not shown.

2. Minutes to Hours & Minutes Converter

Problem: Convert minutes to hours and remaining minutes. Use // and %.

Write your code here – solution not shown.