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Perl Conditional Statements

Perl conditional statements are executed based on the result (True or False) of one or more statements to determine the execution of code blocks.

You can get a simple understanding of the execution process of conditional statements through the following diagram:

>

Note that the number 0, the string '0', "", an empty list(), and undef are false, and all other values are true. Using ! or not before true returns false.

Perl provides the following conditional statements:

Statement Description
if statement An if statement consists of a Boolean expression followed by one or more statements.
if...else statement An if statement can be followed by an optional else statement, which executes when the Boolean expression is false.
if...elsif...else statement You can have an if statement followed by an optional elsif statement, and then another else statement.
unless statement An unless statement consists of a Boolean expression followed by one or more statements.
unless...else statement An unless statement can be followed by an optional else statement.
unless...elsif...else statement An unless statement can be followed by an optional elsif statement, and then another else statement.
switch statement In the latest version of Perl, we can use the switch statement, which executes corresponding code blocks based on different values.

Ternary Operator ? :

We can use the conditional operator ? : to simplify the if...else statement. The general format is:

Exp1 ? Exp2 : Exp3;

If Exp1 is true, it returns the result of Exp2, otherwise it returns Exp3.

Here is an example:

Example

#!/usr/local/bin/perl

$name = "tutorialpro.org";
$favorite = 10;     # Number of likes

$status = ($favorite > 60 )? "Popular Site" : "Not a Popular Site";

print "$name - $status\n";

Executing the above program will output:

tutorialpro.org - Not a Popular Site
❮ Perl Regular Expressions Perl Process Management ❯