Why Python?

Python is one of the most popular and easy-to-learn programming languages. Its simplicity, readability, and vast ecosystem of libraries make it ideal for both beginners and experienced developers.

Getting Started with Python

1. Installing Python

• Step 1: Download Python from the official Python website.
• Step 2: Follow installation instructions for your operating system (Windows, MacOS, Linux).
• Step 3: Verify installation by opening a terminal or command prompt and typing:

2. Running Python Code

You can run Python code in various ways:

• Interactive Python Shell: Open your terminal and type python to start a session.
• Script Mode: Save your code in a .py file (e.g., hello.py) and run it in the terminal:

Basic Syntax and Data Types

3. Hello, World!

Let’s write your first Python program:

4. Variables and Data Types

In Python, variables are dynamically typed. You don’t need to declare them explicitly.

 # Variable assignment
name = "Alice"       # String
age = 30             # Integer
height = 5.6         # Float
is_student = False   # Boolean

print(name, age, height, is_student)

Python has several built-in data types:

• Strings (str)
• Integers (int)
• Floats (float)
• Booleans (bool)

5. Input from Users

You can capture user input with the input() function:

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

Control Flow

6. Conditional Statements

Python uses if, elif, and else for conditional logic:

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

if age >= 18:
    print("You are an adult.")
elif age > 12:
    print("You are a teenager.")
else:
    print("You are a child.")

7. Loops

Python supports for and while loops:

# For loop
for i in range(5):
    print(i)

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

Functions

8. Defining Functions

Functions allow you to reuse code and make it more modular:

def greet(name):
    print("Hello, " + name)

greet("Raghu")
greet("Babu")

You can also return values from functions:

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

result = add(5, 3)
print(result)

Data Structures

9. Lists

Lists are ordered collections of items:

fruits = ["apple", "banana", "cherry"]
print(fruits)

# Accessing items
print(fruits[1])  # Outputs 'banana'

# Adding items
fruits.append("orange")

# Removing items
fruits.remove("banana")

# Looping through a list
for fruit in fruits:
    print(fruit)

10. Dictionaries

Dictionaries store key-value pairs:

person = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

# Accessing values
print(person["name"])

# Adding a new key-value pair
person["job"] = "Engineer"

# Looping through a dictionary
for key, value in person.items():
    print(key, value)

File Handling

11. Reading and Writing Files

Python makes it easy to read from and write to files:

# Writing to a file
with open("example.txt", "w") as file:
    file.write("Hello, World!")

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

Object-Oriented Programming (OOP)

12. Classes and Objects

Classes define the blueprint for objects. Here's an example of how to create a class:

class Dog:
    def __init__(self, name, breed):
        self.name = name
        self.breed = breed

    def bark(self):
        print(self.name + " is barking!")

# Creating an object of the class
my_dog = Dog("Buddy", "Golden Retriever")
my_dog.bark()

Conclusion

This guide covers the basics of Python, from installation to writing basic scripts and using data structures. Once you're comfortable, explore advanced topics like libraries (NumPy, pandas), web frameworks (Django, Flask), and automation!