unless elsif else statement in perl-IGI

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In Perl, the unless statement can also be used with multiple elsif clauses and an else clause to create complex conditional statements. The syntax for an unless elsif else statement is as follows:

unless (condition1) {
    # code to be executed if condition1 is false
}
elsif (condition2) {
    # code to be executed if condition1 is false and condition2 is true
}
elsif (condition3) {
    # code to be executed if condition1 and condition2 are false and condition3 is true
}
...
else {
    # code to be executed if all conditions are false
}

Here is an example to demonstrate how unless elsif else statement works:

my $number = 15;

unless ($number == 10) {
    print "The number is not 10.\n";
}
elsif ($number == 20) {
    print "The number is 20.\n";
}
elsif ($number == 15) {
    print "The number is 15.\n";
}
else {
    print "The number is neither 10 nor 20 nor 15.\n";
}

In this example, the output will be:

The number is 15.

Because the first condition $number == 10 is false, the second condition $number == 20 is also false, but the third condition $number == 15 is true, so the code inside the block for the third elsif clause is executed.

If the value of $number were not 15, the output would have been different depending on the value of $number. If $number were 10, the output would have been:

The number is not 10.

If $number were 20, the output would have been:

The number is 20.

If $number were any value other than 10, 15, or 20, the output would have been:

The number is neither 10 nor 20 nor 15.

Note that the unless elsif else statement is similar to the if elsif else statement, but the condition is inverted. The unless statement is used when you want to execute code when a condition is false, and the if statement is used when you want to execute code when a condition is true.

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unless elsif else statement in perl