Python Tutorial - ntroduction

Python is one of the most popular programming languages right now, especially with the rise of AI technology. Python is a multi-purpose programming language for developing many things like web applications, back-end services, and data science and machine learning.

Setup

These are the preparations for coding with Python:

1. Download the Python then install it.
2. You can use any text editor for writing Python code like Visual Studio Code or a dedicated IDE like PyCharm.

Writing the First Code

Create a new file with a .py extension called main.py. Then write this code.

print("Hello World!")

Run this command to execute Python code.

python main.py

This is the output.

Hello World!

Based on the code above, the print() function displays the Hello World! text.

Variable and Data Types

A variable is a place for storing values like integers, floating numbers, and strings (a bunch of alphanumeric characters). This is an example of variable usage in Python.

number = 42 username = "John Doe" price = 2.95

To display the value from a variable, use print() function.

number = 42 username = "John Doe" price = 2.95 # display a value from variable print("this is a number", number) print("price: ", price) # using formatting print(f"hello, my username is {username}")

This is the output.

this is a number 42 price: 2.95 hello, my username is John Doe

This is the list of commonly used data types in Python.

Operator

There are many basic arithmetic operators in Python. These operators can be used to perform calculations for number data types like integer and float.

This is an example of operator usage in Python.

first = 4 second = 2 addition = first + second subtraction = first - second multiplication = first * second division = first / second mod = first % second square_of_first = first ** 2 print(f'{first} + {second} = {addition}') print(f'{first} - {second} = {subtraction}') print(f'{first} * {second} = {multiplication}') print(f'{first} / {second} = {division}') print(f'{first} % {second} = {mod}') print(f'{first} ** {2} = {square_of_first}')

Output

4 + 2 = 6 4 - 2 = 2 4 * 2 = 8 4 / 2 = 2.0 4 % 2 = 0 4 ** 2 = 16

The // operator performs division and then returns the floor of a division result.

result = 29 // 5 # returns 5 (actual value before floor operation: 5.8)

Adding User Input

The input() function reads the input from the user. This function is useful for creating interactive programs in Python. By default, the input() returns String data type.

This is the basic example of using the input() function.

# get username from input username = input("enter username: ") # get age from input # the int() function converts string into integer data type age = int(input("enter age: ")) print(f"username: {username}") print(f"age: {age}")

Output

Example 1 - Rectangle Area Calculation

Let's create a rectangle area calculation program in Python. The program allows the user to enter the length and width of the rectangle. Then, the program calculates the area of the rectangle and then displays it to the user.

# get length from user input length = int(input("enter length: ")) # get width from user input width = int(input("enter width: ")) # calculate the area of rectangle area = length * width # display the result print(f"area of rectangle: {area}")

Output

Example 2 - Get Discounted Price

Let's create a program to calculate the price of an item after the discount is applied. The program allows the user to enter the actual price and discount. Then, the program returns the discounted price.

# get price from user input price = int(input("enter price: ")) # get discount from user input discount = int(input("enter discount: ")) # calculate the discounted price discounted_price = price - (price * (discount / 100)) # display the result print(f"original price: {price}") print(f"discounted price: {discounted_price}")

Output

Sources

• Python Official Page.
• Python Tutorial.

I hope this article helps you learn Python. If you have any feedback, please let me know in the comment section.

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