Your First Python Program: Hello World and Understanding Indentation

Every programming journey begins with a simple "Hello, World!" program. In Python, this first program teaches you not just how to display text, but also introduces one of Python's most distinctive features: indentation-based code structure.

🚀 Creating Your First Python Program

Let's start by creating a simple Python file and running your first program. This hands-on approach will give you immediate feedback and build confidence.

📝 Step 1: Create Your Python File

Let's start by creating a Python file in your terminal:

touch hello.py
ls

You should see your newly created hello.py file listed in the directory.

💻 Step 2: Open Your Development Environment

Open your current directory in VS Code (or your preferred editor):

code .

This command opens VS Code with your current directory, allowing you to edit the hello.py file directly.

🎯 Step 3: Your First "Hello World" Program

Let's add some content to your Python file. Start with the classic "Hello World" program:

print("Hello world!")

Now run your program from the terminal:

$ python hello.py
Hello world!

🎉 Congratulations! You've just written and executed your first Python program!

Understanding the print() Function

The print() function is one of Python's built-in functions that displays text to the console:

# Basic print statement
print("Hello world!")

# Print with variables
name = "Alice"
print("Hello", name)

# Print multiple items
print("Hello", "world", "from", "Python!")

# Print with formatting
age = 25
print(f"I am {age} years old")

🔀 Step 4: Adding Conditional Logic

Now let's enhance our program by adding a conditional statement. Update your hello.py file:

if True:
    print("This will always print because the condition is true")
print("Hello world!")

Run the updated program:

$ python hello.py
This will always print because the condition is true
Hello world!

Notice how both lines are printed - the conditional statement executes first, then the regular print statement.

⚠️ Step 5: Understanding Python Indentation

Here's where Python differs from many other programming languages. Let's intentionally create an indentation error to understand this crucial concept:

if True:
print("This will always print because the condition is true")
print("Hello world!")

When you run this version:

$ python hello.py
  File "/home/centos9/Razzaq-Labs-II/random/hello.py", line 2
    print("This will always print because the condition is true")
    ^
IndentationError: expected an indented block

🎯 Step 6: Fixing the Indentation

Let's fix the indentation error by properly indenting the code inside the if block:

if True:
    print("This will always print because the condition is true")
print("Hello world!")

Now when you run the program:

$ python hello.py
This will always print because the condition is true
Hello world!

Perfect! The program runs without errors and produces the expected output.

📏 Understanding Python's Indentation Rules

Why Indentation Matters

Python uses indentation to determine which statements belong together in a block. This makes Python code highly readable but requires careful attention to spacing.

if True:
    print("Inside if block")
    print("Also inside if block")
print("Outside if block")

for i in range(3):
    print(f"Loop iteration {i}")
    if i == 1:
        print("Special case")
print("After loop")

if True:
print("Missing indentation")

for i in range(3):
    print(f"Loop iteration {i}")
  print("Inconsistent indentation")

if True:
    print("First line")
        print("Too much indentation")

🚨 Common Indentation Errors and Solutions

# Wrong
if True:
print("Hello")

# Correct
if True:
    print("Hello")

# Wrong
if True:
    print("First line")
  print("Wrong indentation")

# Correct
if True:
    print("First line")
    print("Correct indentation")

# Wrong (mixing tabs and spaces - hard to see!)
if True:
    print("Using spaces")
	print("Using tab")

# Correct (consistent spaces)
if True:
    print("Using spaces")
    print("Also using spaces")

🎯 Key Takeaways

📖 Further Reading

Official Resources

• Python Tutorial - First Steps
• PEP 8 Style Guide
• Python Indentation Documentation

💬 Discussion

I'd love to hear about your first Python programming experience:

• What was your biggest "aha!" moment about Python indentation?
• Have you encountered any tricky indentation errors?
• What other programming languages have you used, and how does Python compare?
• What type of programs are you excited to build with Python?

Connect with me:

• 🐙 GitHub - Python examples and beginner projects
• 📧 Contact - Python learning questions and discussions