my $test = 'illegal\\\\characters*example?';
my @illegal = qw(\ * ?);
my @legal = qw(bs a q);
my $c = 0;
foreach my $val (@illegal) {
    $test =~ s/\Q$val\E/[$legal[$c]]/g;
    $c++;
}
print $test."\n";

##</code><code>##

           A single-quoted, literal string.  A backslash
           represents a backslash unless followed by the
           delimiter or another backslash, in which case the
           delimiter or backslash is interpolated.

##</code><code>##

my $test = 'illegal\\\\characters*example?';
my @illegal = qw(\ * ?);
my @legal = qw(bs a q);
my $c = 0;
foreach my $val (@illegal) {
    $test =~ s/\Q$val\E/[$legal[$c]]/g;
    $c++;
}
print $test."\n";