Tinkering with Perl

(Search & Sitemap) > Writing > Miscellaneous Nonfiction > Tinkering with Perl
Skip Back Previous 16 17 18 19 20 21 22 23 24 25 Next Skip Forward
Printer-Friendly Version

Comments

When you are writing a program, you are writing for people as well as computers. Most of the time, after a program is written, you or someone else will want to make changes -- to add new features, or to fix bugs. There is a joke which my father likes to tell:

A construction worker, at lunch break, opens his lunchbox, and says, "Salami again! I hate bologna!"

Then, the next day, he says, "I wonder what I have today." He opens his lunchbox, and says, "Bologna again? I hate bologna!"

This continues for a week. Finally, one of his coworkers says, "Why don't you ask your wife to give you something else for lunch? That way, you wouldn't have to have bologna all the time."

The construction worker says, "Oh, I don't have a wife. I make my own lunches!"

In this joke, the construction worker eats the sandwiches he hates because that's what he made earlier. This joke is a lot like programming. The construction worker is like a programmer, and the yucky bologna sandwiches are programs that don't have very many little notes, in English, to explain things. It can be very difficult, even for experienced programmers, to figure out or remember what a program is doing if it doesn't have notes to explain things. These little notes are called comments, and you can say anything you like in a comment. (But we generally use comments to explain programs.)

Comments are done differently in different computer languages, but there is some feature that tells the computer what is a comment and what is the rest of the program. In perl, a comment begins with a hash mark ('#'), and continues to the end of the line. If you want to make a comment that uses more than one line, put a hash mark on a second line. Here are some examples of what is and is not a comment:

# This is a comment.

# This is a comment, which
# uses more than one line.

#
# This is a comment, too.  It uses blank lines to make
# things better to look at.
#

                # This is a comment which begins in the
		# middle of a line.  You can put a
		# comment to the right of something 
		# else, to explain what it does.

This is not a comment.

The comment begins #here.

Tinkering with Perl

Comments

See also: