#!/usr/bin/perl -w

use strict;
use warnings;

my $d = "This is a double-quote string\n";
my $s = 'This is a single-quote (apostrophe) string' . "\n";

print $d;
print $s;

# Results ...

BEGIN { $^W = 1; }
use warnings;
use strict 'refs';
my $d = "This is a double-quote string\n";
my $s = "This is a single-quote (apostrophe) string\n";
print $d;
print $s;
quotes.pl syntax OK