Comments

As programs get bigger and more complicated, they get more difficult to read. Good programmers try to make their code understandable to others, but it is still tricky to look at a large program and figure out what it is doing and why.

Best practice encourages us to add notes to our programs, which clearly explain what the program is doing. These notes are called comments.

A comment is text within a program intended only for a human reader—it is completely ignored by the compiler or interpreter. In Python, the # token starts a comment, and the rest of the line gets ignored. For comments that stretch over multiple lines, each line must begin with a #.

# This Example shows off comments!

# print("This does not print.")

print("Hello, World!") # Comments do not have to start at the beginning of a line.

# Here is how
# to have
# multi-line
# comments.

print("Comments make your code more readable by others.")

Experiment with Comments

1. On your own computer, in data-analysis-projects, locate the how-to-write-code folder. Within that folder, you will find an example called Comments.py. You should use the terminal to do so. Here are the steps:

   1. To navigate inside the how-to-write-code folder, use the command cd data-analysis-projects/how-to-write-code.
   2. Open up the required example in Visual Studio Code by running the command, code Comments.py.

2. You are ready to add and remove comments! Here is what the starter code looks like:

   # This demo shows off comments!
   
   # print("This does not print.");
   
   print("Hello, World!"); # Comments do not have to start at the beginning of a line.
   
   # Here is how
   # to have
   # multi-line
   # comments.
   
   print("Comments make your code more readable by others.");

3. Try removing or un-commenting some code first. Then try adding both a single-line and multi-line comment.