From: "Johnson, Tracy" <[log in to unmask]>
>Does anyone know of or have a program that
>can print all upper and lowercase permutations
>of a string?
#!perl -w

listall(join " ", @ARGV);

sub listone {
  print $_[0], "\n";
}

sub listall {
  enumerall(\&listone, "", $_[0])
}

sub enumerall  {
  my ($sub, $sofar, $rest) = @_;
  if (length($rest) == 0) {
    &$sub($sofar);
  } else {
    my $nextchar = substr($rest, 0, 1);
    $rest = substr($rest, 1);
    if (uc($nextchar) eq lc($nextchar)) {
      enumerall($sub, $sofar . $nextchar, $rest);
    } else {
      enumerall($sub, $sofar . uc($nextchar), $rest);
      enumerall($sub, $sofar . lc($nextchar), $rest);
    }
  }
}

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