Python Example

First Python Program

1. Writing the Code

Create a file called hello_world.py (the.py extension designates it as a Python file).

# This is a comment. Python doesn't look at comments, but they explain your code so nicely.

# Prints a message on the console as well.
print("Hello, World!")

2. Explanation of Code

1. Comments (# This is a comment):

• Comments are not read by Python.
• Use comments to explain what your code does. They start with a #.

2. The print() function:

• print() is a native Python built-in function that prints outputs to your screen.
• The text that you want to print is in double quotes or single quotes (" or ').

3. The Message ("Hello, World!"):

• "Hello, World!" is a string-that is, a sequence of characters written between quotes.
• This is the output of a program.

3. Running the Code

Once you have written the code, follow these steps to execute it:

On Your Computer

1. Open terminal or command prompt.
2. Change to the directory where your Python file is saved.
3. Type the following command and then press ENTER:

                    python hello_world.py

Or if you are using Python 3:

                   python3 hello_world.py

Output:

You must be seeing the following on your computer screen:

                   Hello, World!

4. Key Concepts for Extreme Beginners

Syntax:

• The syntax of Python is very simple, and human-readable, so it becomes easy to learn for beginners.

Indentation:

• Python uses identation (spaces or tabs) to define blocks of code.

Error messages:

• If anywhere goes wrong (for example, a single quotation misses), the respective error message will be shown by Python and it can help you to debug.

5. Experimentation

Go ahead and modify it in the following way:

• Change the message:

       print("Welcome to Python!")

• Add another line:

       print("Learning Python is fun!")