 Perl Programming Page 2 - Perl Conditionals |
You Better or Else! - PerlWhile Perl truly is the programming language of the slacker, the bored, and the (okay I'll say it with great lamentation) creative, it is also a harsh mistress. But let's face it: as a computer programmer, you are luck to have a mistress at all. So chin up. Perl doesn't just freely give you love. There are conditions, or, more precisely, conditionals, which is the topic of this fourth part in a series.
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Part of being a rich, illustrious writer is bossing people around. Many times throughout the day I will berate the employees around me, sending them scurrying for cover. [Well, you can dream. --Ed.] When they don't do what I like or want, I give them an If Statement with an Else clause. #!/usr/bin/perl $do_my_bidding = 'Yes Master!'; if ($do_my_bidding = 'Yes Master!' { print "You are a good slave. Tell your mother I will see her tonight"; } else { print "You ignorant buffoon! Tell your mother I will see her on my lunch break!"; print "Get out of my sight!"; In the above code, if $do_my_bidding holds the value, "Yes Master!" you will get the following result: You are a good slave. Tell your mother I will see her tonight. Get out of my sight! If the value of $do_my_bidding held any other value, you would see this: You ignorant buffoon! Tell your mother I will see her on my lunch break! Get out of my sight! No matter which condition is met, the program will always print: Get out of my sight!, as it is not part of either conditional. Elsif Sometimes one Else clause is not enough. That's where Elseif comes in handy. Observe! #!/usr/bin/perl $do_my_bidding = 'Yes Master!'; { print "You are a good slave. Tell your mother I will see her tonight"; } elsif ($do_my_bidding = 'No') print "Insolent swine! Tell your mother to come right now!"; else { print "You ignorant buffoon! Tell your mother I will see her on my lunch break!"; print "Get out of my sight!"; Again, with the above code, if the value of $do_my_bidding is "Yes Master!" it will result in: You are a good slave. Tell your mother I will see her tonight. Get out of my sight! If the value of $do_my_bidding is "No" the following would print to your screen: Insolent swine! Tell your mother to come right now! Get out of my sight! And finally, if the value of $do_my_bidding is anything else, it will print: You ignorant buffoon! Tell your mother I will see her on my lunch break! Get out of my sight! You will note two things: 1) The phrase "Get out of my sight!" is always printed as it is outside of the statements. And 2) No matter what you say, I am still going to spend some time with your mother. It's simply a matter of when.
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