Getting Started

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

1. Why Python?

  • Easy to read and write.
  • Extensive standard library and third-party packages.
  • Versatile, used in web development, data analysis, machine learning, and more.
  • Large community and excellent documentation.

2. Installing Python

Download and Install Python:

  • Visit python.org.
  • Download the latest version for your operating system (Windows, macOS, Linux).
  • Run the installer and follow the instructions. Make sure to check the option to add Python to your system PATH during installation.

Verify Installation:

Open your command line interface (CLI) and type:

python --version

You should see the version of Python you installed.

3. Basic Syntax

Hello, World!

Let's start with a simple program to print "Hello, World!" to the console.

print("Hello, World!")

Run this code in a Python environment, such as an IDE or directly in a Python shell.

Comments

Comments in Python are indicated by the # symbol.

# This is a single-line comment
print("Hello, World!")  # This prints Hello, World!

4. Data Types and Variables

Variables

Variables store information to be referenced and manipulated in a program.

name = "Alice"  # String
age = 25        # Integer
height = 5.5    # Float
is_student = True  # Boolean

Data Types

  • int: Integer (e.g., 1, 2, 3)
  • float: Floating point number (e.g., 1.0, 2.5)
  • str: String (e.g., "hello")
  • bool: Boolean (e.g., True, False)

5. Operators

Arithmetic Operators

x = 10
y = 3
print(x + y)  # Addition
print(x - y)  # Subtraction
print(x * y)  # Multiplication
print(x / y)  # Division
print(x % y)  # Modulus
print(x ** y) # Exponentiation

Comparison Operators

print(x == y)  # Equal to
print(x != y)  # Not equal to
print(x > y)   # Greater than
print(x < y)   # Less than
print(x >= y)  # Greater than or equal to
print(x <= y)  # Less than or equal to

6. Control Flow

If-Else Statements

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

For Loops

for i in range(5):
    print(i)

While Loops

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

7. Functions

Functions are reusable blocks of code that perform a specific task.

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

print(greet("Alice"))

8. Collections

Lists

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

Tuples

point = (10, 20)
print(point[0])  # Access the first element

Dictionaries

person = {"name": "Alice", "age": 25}
print(person["name"])  # Access the value for the key "name"
person["age"] = 26     # Update the value for the key "age"
print(person)

Sets

unique_numbers = {1, 2, 3, 2, 1}
print(unique_numbers)  # Output: {1, 2, 3}

9. File Handling

Reading from a File

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

Writing to a File

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

10. Modules and Packages

Importing a Module

import math
print(math.sqrt(16))  # Using a function from the math module

Importing Specific Functions

from math import pi, sqrt
print(pi)
print(sqrt(16))

11. Introduction to Object-Oriented Programming (OOP)

Defining a Class

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

    def greet(self):
        return f"Hello, my name is {self.name} and I am {self.age} years old."

person1 = Person("Alice", 25)
print(person1.greet())

This covers the basics of Python. Practice writing code and exploring more features to become proficient. If you have specific questions or need further details on any topic, feel free to ask!

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