Beginning Web Development With Perl : From Novice to ... - Nabo

290APPENDIX ■ PERL BASICSCan you see how Perl did this? Well, we simply escaped the backslashes and single quotes.It will help you to sort out what is happening if you look at each element individually. Remember,there are three arguments in this example. Don’t let all the quotes confuse you.Actually, there’s an altogether sneakier way of doing it. Internally, Windows allows you toseparate paths in the Unix style with a forward slash, instead of a backslash. If you’re referringto directories in Perl on Windows, you may find it easier to use C:/WINNT/Profiles/ instead.This allows you to get the variable interpolation of double-quoted strings without the “leaningtoothpick syndrome” of multiple backslashes.So much for backslashes—what about quotation marks? The trick is making sure Perlknows where the end of the string is. Naturally, there’s no problem with putting single quotesinside a double-quoted string, or vice versa:#!/usr/bin/perl -w# quotes3.plprint "It's as easy as that.\ n";print '"Stop," he cried.', "\ n";This will produce the quotation marks in the right places:$ perl quotes3.plIt's as easy as that."Stop," he cried.$The trick comes when we want to have double quotes inside a double-quoted string orsingle quotes inside a single-quoted string. As you might have guessed, though, the solution isto escape the quotes on the inside. Suppose we want to print out the following quote, includingboth sets of quotation marks:'"Hi," said Jack. "Have you read Slashdot today?"'Here’s a way of doing it with a double-quoted string:#!/usr/bin/perl -w# quotes4.plprint "'\ "Hi,\ " said Jack. \ "Have you read Slashdot today?\ "'\ n";Now see if you can modify this to make it a single-quoted string—don’t forget that \ nneeds to go in separate double quotes to make it interpolate.q// and qq//It would be nice if you could select a completely different set of quotes so that there would beno ambiguity and no need to escape any quotes inside the text. The first operators we’re goingto meet are the quote-like operators that do this for us. They’re written as q// and qq//, thefirst acting like a single-quoted string, and the second like a double-quoted string. Nowinstead of the preceding, we can write#!/usr/bin/perl -w