use strict ;
use warnings ;
use Data::Dumper ;

my @ar ;
$ar[0] = undef ;
$ar[2] = 3 ;

if ( exists $ar[0] ) {
	print "0 exists\n" ;
}
if ( exists $ar[1] ) {
	print "1 exists\n" ;
}
if ( exists $ar[2] ) {
	print "2 exists\n" ;
}
if ( exists $ar[3] ) {
	print "3 exists\n" ;
}
print Dumper(\@ar) ;