🐍 30 Days Of Python

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30 Days Of Python: Day 1 - Introduction

_{Author: Asabeneh Yetayeh}

Second Edition: July, 2021

🇧🇷 Portuguese 🇨🇳 中文

Day 2 >>

• 🐍 30 Days Of Python
  • 🙌 Become a Sponsor
• 📘 Day 1
• Welcome
• Introduction
• Why Python ?
• Environment Setup
  • Installing Python
  • Python Shell
  • Installing Visual Studio Code
  • How to use visual studio code
• Basic Python
  • Python Syntax
  • Python Indentation
  • Comments
  • Data types
  • Number
  • String
  • Booleans
  • List
  • Dictionary
  • Tuple
  • Set
  • Checking Data types
  • Python File
• 💻 Exercises - Day 1
  • Exercise: Level 1
  • Exercise: Level 2
  • Exercise: Level 3

📘 Day 1

Welcome

Congratulations for deciding to participate in a 30 days of Python programming challenge. In this challenge, you will learn everything you need to be a python programmer and the whole concept of programming. In the end of the challenge you will get a 30DaysOfPython programming challenge certificate.

If you would like to actively engage in the challenge, you may join the 30DaysOfPython challenge telegram group.

Introduction

Python is a high-level programming language for general-purpose programming. It is an open source, interpreted, object-oriented programming language. Python was created by a Dutch programmer, Guido van Rossum. The name of the Python programming language was derived from a British sketch comedy series, Monty Python's Flying Circus. The first version was released on February 20, 1991. This 30 days of Python challenge will help you learn the latest version of Python, Python 3 step by step. The topics are broken down into 30 days, where each day contains several topics with easy-to-understand explanations, real-world examples, and many hands on exercises and projects.

This challenge is designed for beginners and professionals who want to learn python programming language. It may take 30 to 100 days to complete the challenge. People who actively participate in the telegram group have a high probability of completing the challenge.

This challenge is easy to read, written in conversational English, engaging, motivating and at the same time, it is very demanding. You need to allocate much time to finish this challenge. If you are a visual learner, you may get the video lesson on Washera YouTube channel. You may start from Python for Absolute Beginners video. Subscribe the channel, comment and ask questions on YouTube videos and be proactive, the author will eventually notice you.

The author likes to hear your opinion about the challenge, share the author by expressing your thoughts about the 30DaysOfPython challenge. You can leave your testimonial on this link

Why Python ?

It is a programming language which is very close to human language and because of that, it is easy to learn and use. Python is used by various industries and companies (including Google). It has been used to develop web applications, desktop applications, system administration, and machine learning libraries. Python is a highly embraced language in the data science and machine learning community. I hope this is enough to convince you to start learning Python. Python is eating the world and you are killing it before it eats you.

Environment Setup

Installing Python

To run a python script you need to install python. Let's download python. If your are a windows user, click the button encircled in red.

If you are a macOS user, click the button encircled in red.

To check if python is installed write the following command on your device terminal.

python3 --version

As you can see from the terminal, I am using Python 3.7.5 version at the moment. Your version of Python might be different from mine by but it should be 3.6 or above. If you manage to see the python version, well done. Python has been installed on your machine. Continue to the next section.

Python Shell

Python is an interpreted scripting language, so it does not need to be compiled. It means it executes the code line by line. Python comes with a Python Shell (Python Interactive Shell). It is used to execute a single python command and get the result.

Python Shell waits for the Python code from the user. When you enter the code, it interprets the code and shows the result in the next line. Open your terminal or command prompt(cmd) and write:

python

The Python interactive shell is opened and it is waiting for you to write Python code(Python script). You will write your Python script next to this symbol >>> and then click Enter. Let us write our very first script on the Python scripting shell.

Well done, you wrote your first Python script on Python interactive shell. How do we close the Python interactive shell ? To close the shell, next to this symbol >>> write exit() command and press Enter.

Now, you know how to open the Python interactive shell and how to exit from it.

Python will give you results if you write scripts that Python understands, if not it returns errors. Let's make a deliberate mistake and see what Python will return.

As you can see from the returned error, Python is so clever that it knows the mistake we made and which was Syntax Error: invalid syntax. Using x as multiplication in Python is a syntax error because (x) is not a valid syntax in Python. Instead of (x) we use asterisk (*) for multiplication. The returned error clearly shows what to fix.

The process of identifying and removing errors from a program is called debugging. Let us debug it by putting * in place of x.

Our bug was fixed, the code ran and we got a result we were expecting. As a programmer you will see such kind of errors on daily basis. It is good to know how to debug. To be good at debugging you should understand what kind of errors you are facing. Some of the Python errors you may encounter are SyntaxError, IndexError, NameError, ModuleNotFoundError, KeyError, ImportError, AttributeError, TypeError, ValueError, ZeroDivisionError etc. We will see more about different Python error types in later sections.

Let us practice more how to use Python interactive shell. Go to your terminal or command prompt and write the word python.

The Python interactive shell is opened. Let us do some basic mathematical operations (addition, subtraction, multiplication, division, modulus, exponentiation).

Let us do some maths first before we write any Python code:

• 2 + 3 = 5
• 3 - 2 = 1
• 3 * 2 = 6
• 3 / 2 = 1.5
• 3 ** 2 = 3 x 3 = 9

In python, we have the following additional operations:

• 3 % 2 = 1 => which means finding the remainder
• 3 // 2 = 1 => which means removing the remainder

Let us change the above mathematical expressions to Python code. The Python shell has been opened and let us write a comment at the very beginning of the shell.

A comment is a part of the code which is not executed by python. So we can leave some text in our code to make our code more readable. Python does not run the comment part. A comment in python starts with hash(#) symbol. This is how you write a comment in python

 # comment starts with hash
 # this is a python comment, because it starts with a (#) symbol

Before we move on to the next sect