Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

if

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 is 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. Everything 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 37.3 uses the if/else structure and shows conditional statements using the ...