Python Basic Syntax: Writing Your First Code

 

Welcome back to your Python learning journey! Now that you’ve installed Python and set up your coding environment, it’s time to start writing actual code. This blog post dives into Python Basic Syntax, the foundation of every Python program. We’ll explore how Python code is structured, how to write clear instructions, and what makes Python’s syntax so beginner-friendly. With plenty of examples and tips, you’ll be writing your own programs in no time. Let’s get coding!

What is Python Syntax?

Syntax is the set of rules that defines how you write code in a programming language, like the grammar of a spoken language. Python’s syntax is designed to be simple and readable, making it easier for beginners to focus on solving problems rather than memorizing complex rules. Unlike languages like C++ or Java, Python uses minimal punctuation and relies on indentation to organize code, which keeps things clean and intuitive.

In this post, we’ll cover:

• Writing your first lines of code
• Using comments
• Understanding indentation
• Writing statements and expressions
• Basic input and output

Your First Python Program

Let’s start with a classic program to print a message to the screen:

1. Open your coding environment (e.g., IDLE, Thonny, or VS Code).
2. Create a new file called welcome.py.
3. Write the following code:
   Python

   print("Hello, Python World!")
4. Save the file and run it:
   • In your terminal, navigate to the file’s folder and type:

     python welcome.py
     

     or python3 welcome.py on Linux/macOS.

   Output: Hello, Python World!

The print() function is your way to display text or numbers on the screen. Notice how simple this is—no curly braces {} or semicolons ; like in other languages. This simplicity is a hallmark of Python’s syntax.

Comments: Explaining Your Code

Comments are lines in your code that Python ignores but help you (and others) understand what your code does. They’re like notes in the margins of a book. In Python, you create comments with the # symbol.

Here’s an example:

Python

# This is a comment - Python skips it print("This will be displayed!") # This is an inline comment

Why Use Comments?

• Explain tricky parts of your code.
• Remind yourself what a program does when you revisit it later.
• Make your code easier for others to understand.

Try this program with comments:

Python

# Program to greet the user name = input("Enter your name: ") # Get user’s name print("Welcome,", name) # Print a personalized greeting

Output (if you enter “Alice”):

Enter your name: Alice
Welcome, Alice

Here, input() asks the user for text, which is stored in the name variable. The comments clarify each step.

Tip: Write clear, concise comments, but don’t overdo it. For obvious code like print("Hello"), a comment might not be necessary.

Indentation: Python’s Unique Feature

Unlike many programming languages that use braces {} to group code, Python uses indentation (spaces or tabs) to define blocks of code. This makes your code visually clear but requires consistency.

For example:

Python

# Correct indentation if True: print("This is indented with 4 spaces") print("This is in the same block") print("This is outside the block")

Output:

This is indented with 4 spaces
This is in the same block
This is outside the block

If you mess up indentation, Python will complain:

Python

if True: print("This is fine") print("This will cause an error") # Wrong indentation

Error: IndentationError: unexpected indent

Rules for Indentation:

• Use 4 spaces per indentation level (most editors do this automatically).
• Be consistent: Don’t mix spaces and tabs.
• All lines in the same block (e.g., inside an if statement) must have the same indentation.

Try this example:

Python

# Check if a number is positive number = int(input("Enter a number: ")) if number > 0: print("The number is positive!") print("Great job entering a number!") print("This runs no matter what")

If you enter 5, the output is:

Enter a number: 5
The number is positive!
Great job entering a number!
This runs no matter what

The indented lines under if only run if the condition (number > 0) is true. Indentation tells Python which lines belong together.

Statements and Expressions

Let’s break down two key building blocks of Python code:

• Statements: Instructions that perform an action, like assigning a value or printing.
  Python

  x = 10 # Assignment statement print(x) # Print statement
• Expressions: Code that evaluates to a value, like a math operation or a function call.
  Python

  result = 5 + 3 # Expression (5 + 3 evaluates to 8) length = len("hello") # Expression (len() returns 5)

Here’s a program combining both:

Python

# Calculate the area of a rectangle width = 5 # Statement: assign 5 to width height = 3 # Statement: assign 3 to height area = width * height # Expression: calculates 15 print("The area is", area) # Statement: print the result

Output: The area is 15

Input and Output

You’ve already seen print() for output and input() for getting user input. Let’s explore them further:

• Output with print():
  • Display text, numbers, or variables.
  • Combine multiple items with commas or f-strings for cleaner formatting:
    Python

    name = "Bob" print("Hello", name) # Output: Hello Bob print(f"Hello, {name}!") # Output: Hello, Bob!
  • Add end to change what comes after the output (default is a newline):
    Python

    print("Hello", end=" ") print("World") # Output: Hello World
• Input with input():
  • Always returns a string, so convert it for numbers:
    Python

    age = int(input("Enter your age: ")) # Convert string to integer print(f"Next year, you’ll be {age + 1}")

  Output (if you enter 20):

  Enter your age: 20
  Next year, you’ll be 21
  

Try this interactive program:

Python

# Simple calculator for doubling a number number = float(input("Enter a number to double: ")) # Works with decimals doubled = number * 2 # Expression print(f"Double {number} is {doubled}") # Formatted output

Output (if you enter 4.5):

Enter a number to double: 4.5
Double 4.5 is 9.0

Putting It All Together: A Practical Example

Let’s create a program that combines comments, indentation, statements, expressions, and input/output to calculate a restaurant tip:

Python

# Restaurant tip calculator print("Welcome to the Tip Calculator!") bill = float(input("Enter the bill amount: $")) # Get bill as a float tip_percent = int(input("Enter tip percentage (e.g., 15): ")) # Get tip % # Calculate the tip and total tip_amount = bill * (tip_percent / 100) # Expression for tip total = bill + tip_amount # Expression for total # Display results with formatting print(f"Bill: ${bill:.2f}") print(f"Tip ({tip_percent}%): ${tip_amount:.2f}") print(f"Total: ${total:.2f}")

Output (if you enter 50 and 15):

Welcome to the Tip Calculator!
Enter the bill amount: $50
Enter tip percentage (e.g., 15): 15
Bill: $50.00
Tip (15%): $7.50
Total: $57.50

This program uses:

• Comments to explain the purpose.
• Indentation to organize code (though not needed here, it will be with if statements later).
• Statements to assign values and print results.
• Expressions to calculate the tip and total.
• Input/output with formatted f-strings (.2f ensures two decimal places).

Common Syntax Mistakes to Avoid

• Indentation Errors: Ensure consistent spacing (4 spaces is standard). Don’t mix tabs and spaces.
• Forgetting Colons: After if, for, or other block starters, always include a colon :
  Python

  if True # Error: missing colon print