A Quick peek to Python programming language

Table of Contents:

Introduction to Python
Installing Python
Running Python Code
Python Syntax Basics
- Variables
- Data Types
- Input and Output
- Comments
Control Flow
- if Statements
- Loops
Functions
Lists and Dictionaries
Working with Files
Libraries and Packages
Conclusion

1. Introduction to Python

Python is a powerful and easy-to-learn programming language. It is known for its simplicity and readability, making it a great choice for beginners.

2. Installing Python

Windows/MacOS: Download the latest version of Python from python.org. The installation package includes everything you need to get started.
Linux: Python is typically pre-installed. You can verify by running python3 --version in the terminal.

3. Running Python Code

You can run Python code in two main ways:

Interactive mode: Open a terminal and type python3 or python, depending on your system, and you will enter the Python interpreter.
Script mode: Write Python code in a file (e.g., example.py), and run it in the terminal with python3 example.py.

4. Python Syntax Basics

Variables

In Python, you can store values in variables. You don’t need to specify the data type when creating them.

name = "John"
age = 25
pi = 3.14

Data Types

Some common data types in Python are:

int: Whole numbers (e.g., 10, -3)
float: Decimal numbers (e.g., 3.14, -1.0)
str: Strings (e.g., “hello”)
bool: Boolean (True or False)

Input and Output

Use the input() function to take user input and print() to display output.

name = input("What is your name? ")
print(f"Hello, {name}!")

Comments

Use # for single-line comments and ''' ''' or """ """ for multi-line comments.

# This is a single-line comment

"""
This is a multi-line comment
that spans multiple lines.
"""

5. Control Flow

`if` Statements

Control the flow of your program using conditional statements.

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

if age >= 18:
    print("You are an adult.")
else:
    print("You are not an adult.")

Loops

for loop: Iterate over a sequence (like a list or string).

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

while loop: Repeats as long as a condition is true.

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

6. Functions

Functions allow you to reuse code by encapsulating logic into callable blocks.

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

greet("Alice")

You can also return values from functions:

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

result = add(3, 4)
print(result)

7. Lists and Dictionaries

Lists

A list is an ordered collection of items.

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

Dictionaries

A dictionary stores key-value pairs.

person = {"name": "John", "age": 30}
print(person["name"])  # Output: John
person["age"] = 31  # Update a value

8. Working with Files

Python makes it easy to work with files. Here’s how to read and write files:

Reading a file:

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

Writing to a file:

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

9. Libraries and Packages

Python has a rich ecosystem of libraries. Use pip to install packages from the Python Package Index (PyPI).

Installing a package:

pip install requests

Using the package:

import requests

response = requests.get("https://api.github.com")
print(response.status_code)

10. Conclusion

Congratulations! You’ve learned the basics of Python. You now know how to:

Write basic Python programs
Use variables, loops, and functions
Work with lists and dictionaries
Handle files
Use external libraries

Continue practicing and exploring more advanced topics like object-oriented programming, data science, web development, and more!