Книга: Fedora™ Unleashed, 2008 edition

if/else

if/else

The syntax of the Perl if/else structure is as follows:

if (condition) {
 statement or block of code
} elsif (condition) {
 statement or block of code
} else {
 statement or block of code
}
condition can be a statement that returns a true or false value.

Truth is defined in Perl in a way that might be unfamiliar to you, so be careful. Every thing in Perl is true except 0 (the digit zero), "0" (the string containing the number 0), "" (the empty string), and an undefined value. Note that even the string "00" is a true value because it is not one of the four false cases.

The statement or block of code is executed if the test condition returns a true value. For example, Listing 25.3 uses the if/else structure and shows conditional statements using the eq string comparison operator.

if ($favorite eq "chocolate") {
 print "I like chocolate too.n";
} elsif ($favorite eq "spinach") {
 print "Oh, I don't like spinach.n";
} else {
 print "Your favorite food is $favorite.n";
}

Оглавление книги