5.12. Perl IF…ELSE statement

One if statement can be followed by an optional else statement else statement in a Boolean expression false when it is executed.

5.12.1. Grammar #

The syntax format is as follows:

if(boolean_expression){
   # In the Boolean expression boolean_ Execute when expression is true
}else{
   # In the Boolean expression boolean_ Expression executed with false
}

If a Boolean expression boolean_expression for true , then execute``if`` the code within the block. If the Boolean expression is false , then execute else the code within the block.

5.12.2. Flow chart #

|C If... else statement|

Example #

#/ Usr/bin/perl $a=100# Use the if statement to determine the Boolean expression if ($a<20){#
When the Boolean expression is true, execute printf "a is less than 20 n";} Else{#
When the Boolean expression is false, execute printf "a is greater than 20 n";} The value of print 'a' is
: $a n "; $a=" "; # Use the if statement to determine the Boolean expression if ($a){#
Execute printf when Boolean expression is true "a condition is true n";} Else{#
When the Boolean expression is false, execute printf 'a condition is false n';} The value of print 'a' is
: $a n ";

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

A greater than 20
The value of a is: 100
Condition a is false
The value of a is: