Perl Conditional Statements

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

You can briefly understand the execution process of conditional statements through the following diagram:

Note that the number0, the string'0' 、 "", emptylist(), andundefisfalse, all other values aretrue. Before true, use!ornotthen it returns false.

Perl provides the following conditional statements:

Statement	Description
if statement	Aif statementconsists of a boolean expression followed by one or more statements.
if...else statement	Aif statementcan be followed by an optionalelse statement, the else statement is executed when the boolean expression is false.
if...elsif...else statement	You can after aifstatement can be followed by an optionalelsif statement, and then follow with anotherelse statement。
unless statement	Aunless statementconsists of a boolean expression followed by one or more statements.
unless...else statement.	Aunless statementcan be followed by an optionalelse statement。
unless...elsif..else statement	Aunless statementcan be followed by an optionalelsif statement, and then follow with anotherelse statement。
switch statement	In the latest version of Perl, we can useswitchstatement. It executes the corresponding code block based on different values.

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Ternary operator ? :

We can useconditional operator ? :to simplifyif...elsethe operation of the statement. The usual format is:

Exp1 ? Exp2 : Exp3;

If the Exp1 expression is true, return the result of the Exp2 expression; otherwise, return Exp3.

The example is as follows:

Executing the above program, the output result is:

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