my ($substr) = $var =~ /(pattern)/;
print $substr, "\n"
   if defined $substr;

##</code><code>##

if ($var =~ /(pattern)/) {
   print "$1\n";
}

##</code><code>##

my @substrs = $var =~ /(pattern)/g;
print "$_\n"
   foreach @substrs;

##</code><code>##

while ($var =~ /(pattern)/g) {
   print "$1\n";
}