This chapter is from the book
This chapter is from the book
This chapter is from the book
Q&A
I'm familiar with another programming language, C, which has a switch (or case) statement. Where is Perl's switch statement?
Perl doesn't have one! Perl provides such a variety of tests that figuring out the best syntax for a switch statement is nightmarish. The simplest way to emulate a switch statement is as follows:
if ($variable_to_test == $value1) {
statement1;
} elsif ($variable_to_test == $value2) {
statement2;
} else {
default_statement;
}
The online syntax manual page—which you can view by typing perldoc perlsyn at a command prompt—contains many clever examples of how to emulate a switch statement in Perl, some with very switch-like syntax.
How many for (while, if) blocks can I nest inside each other?
As many as you like, within memory restrictions of your system. Usually, however, if you have deeply nested loops, it is a sign that you should approach the problem differently.
Help! Perl is giving me the message Unmatched right bracket (or Missing right bracket). The line number reported is the end of the file!
Somewhere in your program, you've used an open brace ({) without a close brace (}), or vice versa. Perl can sometimes guess where the typo is in your program, but sometimes not. Because control structures can nest arbitrarily deeply, Perl doesn't know you've made a mistake until it unexpectedly reaches the End of File without finding the balancing brace. A good program editor (such as vi, Emacs, or UltraEdit) has features to help you find mismatched braces. Use one.