Beginner’s Guide: Creating Your First Simple Python Program

Python is a versatile and beginner-friendly programming language that’s widely used for web development, data science, artificial intelligence, and more. If you’re new to programming, Python is an excellent choice to start with. This guide will walk you through creating a very simple Python program step-by-step, explaining each concept along the way.

Why Python?

Before we dive into the code, let’s briefly discuss why Python is a great language for beginners:

Readability: Python’s syntax is designed to be clean and easy to understand, resembling plain English.
Large Community and Resources: Python has a massive and active community, meaning there’s plenty of support and resources available online.
Versatility: Once you learn Python, you can apply your skills to various domains.
Cross-Platform Compatibility: Python runs seamlessly on Windows, macOS, and Linux.

Prerequisites

Before you start writing Python code, you’ll need to have Python installed on your computer. Here’s how to do it:

1. Downloading Python

Go to the official Python website: https://www.python.org/downloads/. Download the latest version of Python compatible with your operating system (Windows, macOS, or Linux). Choose the appropriate installer based on your operating system.

2. Installing Python on Windows

Run the downloaded installer (.exe file).
Make sure to check the box that says “Add Python X.X to PATH” (where X.X is the version number). This is crucial for running Python from the command line.
Click “Install Now” to start the installation process.
Once the installation is complete, click “Close.”

3. Installing Python on macOS

Run the downloaded installer (.pkg file).
Follow the on-screen instructions to complete the installation.
The installer will place Python in the /Applications/Python X.X directory.

4. Installing Python on Linux

Python is often pre-installed on Linux systems. However, you may need to install a specific version or update the existing one. Use your distribution’s package manager to install Python. For example, on Debian/Ubuntu, you can use the following command in the terminal:

sudo apt update
sudo apt install python3

On Fedora/CentOS/RHEL, use:

sudo dnf update
sudo dnf install python3

5. Verifying the Installation

To verify that Python is installed correctly, open a command prompt (Windows) or terminal (macOS/Linux) and type the following command:

python --version

or, in some systems, especially after a fresh install next to a python 2.x version

python3 --version

If Python is installed correctly, you should see the Python version number displayed (e.g., Python 3.9.7). If you see an error message, double-check that you added Python to the PATH environment variable during installation (Windows) or that Python is correctly installed and accessible in your terminal.

Choosing a Text Editor

You’ll need a text editor to write your Python code. While you can use a simple text editor like Notepad (Windows) or TextEdit (macOS), it’s highly recommended to use a code editor that provides features like syntax highlighting, code completion, and debugging support. Some popular code editors include:

Visual Studio Code (VS Code): A free and powerful editor with excellent Python support.
Sublime Text: A popular editor known for its speed and customizability (requires a license for extended use).
PyCharm: A dedicated Python IDE (Integrated Development Environment) with advanced features (available in both free Community and paid Professional editions).
Atom: A customizable and open-source editor developed by GitHub (now archived, but still usable).
IDLE: A basic IDE included with Python installations.

For this tutorial, you can use any text editor you prefer. VS Code is a solid choice for beginners.

Our First Python Program: “Hello, World!”

The traditional first program in any programming language is the “Hello, World!” program. It’s a simple program that displays the text “Hello, World!” on the screen. Here’s how to create it in Python:

1. Open Your Text Editor

Launch your chosen text editor (e.g., VS Code, Sublime Text, PyCharm).

2. Create a New File

Create a new file in your text editor. You can usually do this by going to File > New File or using the keyboard shortcut Ctrl+N (Windows/Linux) or Cmd+N (macOS).

3. Write the Code

Type the following line of code into the file:

print("Hello, World!")

4. Save the File

Save the file with a .py extension. For example, you can save it as hello.py. Choose a location on your computer where you want to save the file.

5. Run the Program

To run the program, you’ll need to use the command line or terminal. Here’s how:

a. Open the Command Line/Terminal

Open a command prompt (Windows) or terminal (macOS/Linux).

b. Navigate to the Directory

Use the cd command to navigate to the directory where you saved the hello.py file. For example, if you saved it in your Documents folder, you might use the following command:

cd Documents

c. Run the Python Program

Type the following command and press Enter:

python hello.py

or, if your system requires it:

python3 hello.py

If everything is set up correctly, you should see the text “Hello, World!” displayed in the command line/terminal.

Understanding the Code

Let’s break down the code we just wrote:

print("Hello, World!")

print(): This is a built-in function in Python. A function is a block of code that performs a specific task. The print() function displays output on the screen.
"Hello, World!": This is a string literal. A string is a sequence of characters (letters, numbers, symbols) enclosed in quotation marks (either single quotes ' or double quotes "). In this case, the string “Hello, World!” is the text that we want to display.

The print() function takes the string as an argument (the value inside the parentheses) and displays it on the screen.

Taking Input from the User

Now, let’s make our program a little more interactive by taking input from the user. We’ll ask the user for their name and then greet them.

1. Create a New File

Create a new file in your text editor (e.g., greeting.py).

2. Write the Code

Type the following code into the file:

name = input("What is your name? ")
print("Hello, " + name + "!")

3. Save the File

Save the file as greeting.py.

4. Run the Program

Open the command line/terminal, navigate to the directory where you saved the file, and run the program using the following command:

python greeting.py

python3 greeting.py

The program will prompt you to enter your name. Type your name and press Enter. The program will then greet you with your name.

Understanding the Code

Let’s break down the code:

name = input("What is your name? ")

input(): This is another built-in function in Python. The input() function prompts the user to enter text from the keyboard. The text inside the parentheses ("What is your name? ") is the prompt that will be displayed to the user.
name =: This is an assignment statement. It assigns the value entered by the user to a variable called name. A variable is a named storage location in memory that can hold a value.

print("Hello, " + name + "!")

"Hello, " and "!": These are string literals.
+: This is the string concatenation operator. It joins two strings together. In this case, it joins the string “Hello, “, the value of the variable name, and the string “!” to create a single string.
print(): This function displays the concatenated string on the screen.

Performing Simple Calculations

Python can also be used to perform calculations. Let’s create a program that adds two numbers together.

1. Create a New File

Create a new file in your text editor (e.g., addition.py).

2. Write the Code

Type the following code into the file:

num1 = input("Enter the first number: ")
num2 = input("Enter the second number: ")

# Convert the input strings to numbers
num1 = float(num1)
num2 = float(num2)

sum = num1 + num2

print("The sum is:", sum)

3. Save the File

Save the file as addition.py.

4. Run the Program

Open the command line/terminal, navigate to the directory where you saved the file, and run the program using the following command:

python addition.py

python3 addition.py

The program will prompt you to enter two numbers. Enter the numbers and press Enter after each one. The program will then display the sum of the two numbers.

Understanding the Code

Let’s break down the code:

num1 = input("Enter the first number: ")
num2 = input("Enter the second number: ")

These lines prompt the user to enter two numbers and store them as strings in the variables num1 and num2.

# Convert the input strings to numbers
num1 = float(num1)
num2 = float(num2)

The input() function always returns a string. To perform calculations, we need to convert the strings to numbers. The float() function converts a string to a floating-point number (a number with a decimal point).

sum = num1 + num2

This line adds the two numbers together and stores the result in the variable sum.

print("The sum is:", sum)

This line displays the sum on the screen. The print() function can take multiple arguments, separated by commas. In this case, it displays the string “The sum is:” followed by the value of the variable sum.

Conditional Statements (if/else)

Conditional statements allow you to execute different blocks of code based on certain conditions. Let’s create a program that checks if a number is positive, negative, or zero.

1. Create a New File

Create a new file in your text editor (e.g., number_check.py).

2. Write the Code

Type the following code into the file:

number = input("Enter a number: ")
number = float(number)

if number > 0:
    print("The number is positive.")
elif number < 0:
    print("The number is negative.")
else:
    print("The number is zero.")

3. Save the File

Save the file as number_check.py.

4. Run the Program

Open the command line/terminal, navigate to the directory where you saved the file, and run the program using the following command:

python number_check.py

python3 number_check.py

The program will prompt you to enter a number. Enter the number and press Enter. The program will then tell you whether the number is positive, negative, or zero.

Understanding the Code

Let’s break down the code:

number = input("Enter a number: ")
number = float(number)

These lines prompt the user to enter a number and convert it to a floating-point number.

if number > 0:
    print("The number is positive.")
elif number < 0:
    print("The number is negative.")
else:
    print("The number is zero.")

if: This is the keyword that starts an if statement. The condition that follows the if keyword (number > 0) is evaluated. If the condition is true, the code block that follows the if statement is executed.
elif: This is short for “else if.” It allows you to check multiple conditions. The condition that follows the elif keyword (number < 0) is evaluated only if the previous if condition is false. If the elif condition is true, the code block that follows the elif statement is executed.
else: This keyword specifies a code block that is executed if none of the previous if or elif conditions are true.
Indentation: Python uses indentation to define code blocks. The code within each if, elif, and else block must be indented (usually by four spaces). Consistent indentation is crucial for Python code to run correctly.

Loops (for and while)

Loops allow you to repeat a block of code multiple times. Python has two main types of loops: for loops and while loops.

For Loop

A for loop is used to iterate over a sequence of items (e.g., a list, a string, or a range of numbers). Let’s create a program that prints the numbers from 1 to 5 using a for loop.

1. Create a New File

Create a new file in your text editor (e.g., for_loop.py).

2. Write the Code

Type the following code into the file:

for i in range(1, 6):
    print(i)

3. Save the File

Save the file as for_loop.py.

4. Run the Program

Open the command line/terminal, navigate to the directory where you saved the file, and run the program using the following command:

python for_loop.py

python3 for_loop.py

The program will print the numbers 1 to 5 on separate lines.

Understanding the Code

for i in range(1, 6):
    print(i)

for i in range(1, 6):: This line starts the for loop. The range(1, 6) function generates a sequence of numbers from 1 (inclusive) to 6 (exclusive), so it generates the numbers 1, 2, 3, 4, and 5. The variable i takes on each value in the sequence, one at a time.
print(i): This line prints the current value of i in each iteration of the loop.

While Loop

A while loop is used to repeat a block of code as long as a certain condition is true. Let’s create a program that prints the numbers from 1 to 5 using a while loop.

1. Create a New File

Create a new file in your text editor (e.g., while_loop.py).

2. Write the Code

Type the following code into the file:

i = 1
while i <= 5:
    print(i)
    i = i + 1

3. Save the File

Save the file as while_loop.py.

4. Run the Program

Open the command line/terminal, navigate to the directory where you saved the file, and run the program using the following command:

python while_loop.py

python3 while_loop.py

The program will print the numbers 1 to 5 on separate lines.

Understanding the Code

i = 1
while i <= 5:
    print(i)
    i = i + 1

i = 1: This line initializes a variable i to 1.
while i <= 5:: This line starts the while loop. The loop continues to execute as long as the condition i <= 5 is true.
print(i): This line prints the current value of i in each iteration of the loop.
i = i + 1: This line increments the value of i by 1 in each iteration of the loop. This is important because it ensures that the loop will eventually terminate (when i becomes greater than 5). Without this line, the loop would run forever (an infinite loop).

Conclusion

Congratulations! You’ve successfully created your first simple Python programs. This tutorial covered the basics of Python programming, including printing output, taking input from the user, performing calculations, using conditional statements, and using loops. With these fundamental concepts, you can start building more complex and interesting programs. Keep practicing and exploring, and you’ll become proficient in Python programming in no time.

Further Exploration

Online Resources: Check out websites like Codecademy, Coursera, and edX for interactive Python courses.
Python Documentation: The official Python documentation is an invaluable resource: https://docs.python.org/3/
Practice Problems: Solve coding challenges on platforms like HackerRank and LeetCode to improve your skills.
Join the Community: Engage with other Python learners on forums, online communities, and local meetups.