5.10. Perl conditional statement

Perl conditional statement is the result of the execution of one or more statements True or False to determine the block of code to execute

You can use the following figure to briefly understand the execution of conditional statements:

/media/sphinx_tuto/img/Q1hUjVgberLytG0p.png

Note that the number 0, string '0' 、 "" , empty list() , and undef for false all other values are true . true previous use ! or not then return to false .

Perl provide the following conditional statements are provided:

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, and the else statement is executed when the Boolean expression is false.
If…elsif…else statement	You can follow an if statement with an optional elsif statement, followed byanother else statement.
Unless statement	A 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, followedby another else statement.
Switch statement	In the latest version of Perl, we can use the switch statement. It executes the corresponding block of code according to different values.

5.10.1. Ternary operator?: #

We can use conditional operations ? : to simplify if...else operation statement. The usual format is:

Exp1 ? Exp2 : Exp3;

If Exp1 the expression is true , then return Exp2 expression evaluates the result, otherwise returns Exp3 .

The example is as follows:

Example #

#/ Usr/local/bin/perl $name="Rookie Tutorial"$ Favorite=10#
Number of likes $status=($favorite>60)? Popular website ":"
Not a popular website "; Print "$name - $status n";

Execute the above program, and the output is as follows:

Novice Tutorial - Not a Popular Website