5.13. Perl IF…ELSIF statement

One if statement can be followed by an optional elsif statement, and then follow another else statement.

This conditional judgment statement is very useful in the case of multiple conditions.

When using the if , elsif , and else statements, you need to pay attention to the following points.

• if statement can be followed by 0 or 1 else statement, but elsif must be in the back else statement.

• if statement can be followed by 0 or 1 elsif statements, but they must be written in the else before the statement.

• If one of them elsif successful execution, others elsif and else will no longer be executed.

if(boolean_expression 1){ # In the Boolean expression boolean_ Expression 1 is executed as true } elsif( boolean_expression 2){ # In the Boolean expression boolean_ Expression 2 is executed as true } elsif( boolean_expression 3){ # In the Boolean expression boolean_ Expression 3 is executed as true } else{ # Executed when all conditions of a Boolean expression are false } 

#/ Usr/bin/perl $a=100# Use==to determine whether two numbers are equal if ($a==20) {# condition is When true, execute printf "a with a value of 20 n";} Elsif ($a==30) {# Condition is true When executing printf "a, the value is 30 n";} Else {# All of the above conditions are false When executing printf 'a', the value is $a n ';} 

The value of a is 100