Day 4: Our First Python Program | 100 Days Python

Day 3: Modules and Pip | 100 Days Python

Python is a fantastic language for beginners and experienced developers alike. Today, we’re diving into the foundational concepts to set you up for success with your very first Python program. From understanding functions to writing and running your own code, we'll guide you step-by-step so you can follow along and get hands-on with Python programming. This guide will focus on understanding each line of code and seeing how Python executes it.

Why “Hello World” in Python?

In programming, the "Hello World" program is traditionally the first step for beginners. It helps you verify that your development environment is set up correctly and allows you to see how code flows in action. When you execute this program in Python, you'll gain a clearer understanding of how functions work, how to print output to the console, and how to structure Python code.

Setting Up Your Python Environment

To get started, open your preferred code editor or environment, like Replit, VSCode, or a Python terminal. We'll be using a Python script to demonstrate how code runs line-by-line, but any setup that can interpret Python will work just as well. You may also want to follow along using the REPL (Read, Evaluate, Print, Loop) for interactive learning.

Writing Your First Python Code: The Print Function

In Python, the print() function is commonly used to output text to the console. This function is foundational and allows us to display any message or result we want.

Let’s take a look at our very first line of code in Python:

print("Hello World")

Understanding the Code

1. print - This is a built-in Python function designed to display the text or data inside the parentheses on the screen.
2. Parentheses () - Parentheses are used in Python to invoke or call functions. When you type print(), you’re calling the print function.
3. Quotation Marks "" - Anything within double quotes (or single quotes) is interpreted as a string—a series of characters. Here, "Hello World" is our string.

When you run this code, the output will be:

Hello World

Common Errors in Python

It’s easy to make minor mistakes, especially as a beginner. Let’s discuss a common error you might encounter.

If you mistakenly type:

print(Hello World)

You’ll receive a syntax error because Python doesn’t recognize Hello World as a string without the quotation marks. To fix this, simply place double or single quotes around Hello World.

Running Code Line-by-Line with Scripts

Scripts allow us to write multiple lines of code that execute sequentially. For example, you can add multiple print statements in a script, and Python will run each line in order. Here’s a short script to illustrate this:

print("Hello World")
print(5)
print("Goodbye!")

Expected Output

Hello World
5
Goodbye!

This method ensures each line runs one after the other, from top to bottom. It’s a practical way to execute code, especially when working with longer programs.

Python for Basic Arithmetic

Python is not only great for printing text; it can also handle arithmetic operations. You can use basic operators within the print function to calculate and display results:

print(17 * 13)

This code multiplies 17 by 13 and outputs the result, 221. You can use other operators like + (addition), - (subtraction), / (division), and * (multiplication) in the same way.

Here’s another example:

# Calculating the cost of okra at Rs.17 per kg for 13 kg
price_per_kg = 17
quantity = 13
total_cost = price_per_kg * quantity
print(total_cost)

The output here would be:

221

Using the REPL for Instant Feedback

If you’re using a Python REPL (Read, Evaluate, Print, Loop) environment, you can execute single commands and immediately see their results. For instance, typing 8 + 9 in the REPL will instantly show 17.

Example

>>> 8 + 9
17

In a script, however, Python will execute a set of instructions in order. This is useful when you want to automate a sequence of steps rather than input each command individually.

Committing to 100 Days of Code

The 100 Days of Code challenge is an excellent way to commit to learning Python. However, consistency is key, and taking on this challenge means dedicating yourself to daily practice. If you’re looking for shortcuts, this course may not be for you; programming requires steady, hands-on practice.

Leave your progress in the comments with "I’m present," and keep practicing to make the most of your coding journey. Remember, there’s no elevator to success—you have to take the stairs!

What’s Next?

This introduction is just the beginning. We’ll cover more advanced topics in the upcoming blogs and write more complex programs. Each lesson will build on the previous one, helping you deepen your understanding of Python step-by-step.

Stay consistent, keep practicing, and you’ll soon find yourself more comfortable with Python. Enjoy your journey through the 100 Days of Code, and remember, Python is a powerful tool that can open doors to countless opportunities in technology.

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