Null True False in Perl

In Perl, you can check if a value is null/true/false by using a conditional statement or a Perl function. Here are some examples:

1. Checking if a value is null:
You can use the defined function to check if a variable is defined or not. If a variable is not defined, it is considered null. For example,

my $var;
if(!defined $var){
  print "The value is null\n";
}

2. Checking if a value is true:
In Perl, most scalar values evaluate to true except for the value undef, 0, '0', "", and the string 'false'. You can use a simple conditional statement to check if a value is true, For example,

my $value = "Hello World";
if($value){
  print "The value is true\n";
}

3. Checking if a value is false:
To check if a value is false, you can use a negation operator ! to negate the value and then check if the result is true. For example,

my $num = 0;
if(!$num){
  print "The value is false\n";
}

Alternatively, you can use the Perl function defined to check if a value is defined or not. If a variable is defined, it is evaluated as true. For example,

my $var;
if(!defined $var){
  print "The value is false\n";
}

These are some ways to check if a value is null/true/false in Perl.