Perl UNLESS...ELSE statement
A Perl
unless statement can be followed by an optional
else
statement, which executes when the boolean expression is true.
Syntax:
The syntax of an
unless...else statement in Perl programming language
is:
unless(boolean_expression){
# statement(s) will execute if the given condition is false
}else{
# statement(s) will execute if the given condition is true
}
If the boolean expression evaluates to
true then the
unless block
of code will be executed otherwise
else block of code will be executed.
Example:
#!/usr/local/bin/perl
$a = 100;
# check the boolean condition using unless statement
unless( $a == 20 ){
# if condition is false then print the following
printf "given condition is false\n";
}else{
# if condition is true then print the following
printf "given condition is true\n";
}
print "value of a is : $a\n";
$a = "";
# check the boolean condition using unless statement
unless( $a ){
# if condition is false then print the following
printf "a has a false value\n";
}else{
# if condition is true then print the following
printf "a has a true value\n";
}
print "value of a is : $a\n";
When the above code is executed, it produces following result:
given condition is false
value of a is : 100
a has a false value
value of a is :
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