Here's a very trivial BF interpreter. Its written in as few lines as possible while trying to keep it readable. It expects BF code on standard input.
#!/usr/bin/perl

$cd .= $_ while (<STDIN>);

sub get_char {
    exit if ($ch_ptr == length($cd));
    return substr($cd, $ch_ptr++, 1);
}

while (1) {
    $ch = get_char;
    $cell[$cl_ptr]++ if ($ch eq '+');
    $cell[$cl_ptr]-- if ($ch eq '-');
    (($_ = chr($cell[$cl_ptr])) && print) if ($ch eq '.');
    $cl_ptr++ if ($ch eq '>');
    $cl_ptr-- if ($ch eq '<');
    if ($ch eq ',') {
        $inp_ch = getc(STDIN);
        $cell[$cl_ptr] = ord($inp_ch);
    } elsif ($ch eq '[') {
        ($ch_ptr = index($cd, ']', $ch_ptr)) if ($cell[$cl_ptr] == 0);
    } elsif ($ch eq ']') {
        ($ch_ptr = rindex($cd, '[', $ch_ptr)) if ($cell[$cl_ptr] != 0)
+;
    }
}

[download]

Replies are listed 'Best First'.
Re: BF Interpreter
by jdporter (Paladin) on Mar 08, 2006 at 22:38 UTC

    Not bad, not bad... 

    {
    my $cd = join '', <>;
    my $ch_ptr = 0;

    sub get_char
    {
        exit if $ch_ptr == length $cd;
        substr $cd, $ch_ptr++, 1;
    }
    sub jump_ahead
    {
        $ch_ptr = index $cd, ']', $ch_ptr
    }
    sub jump_behind
    {
        $ch_ptr = rindex $cd, '[', $ch_ptr
    }
}

my @cell;
my $cl_ptr = 0;

my %disp = (
    '+' => sub { $cell[$cl_ptr]++ },
    '-' => sub { $cell[$cl_ptr]-- },
    '.' => sub { print chr($cell[$cl_ptr]) },
    '>' => sub { $cl_ptr++ },
    '<' => sub { $cl_ptr-- },
    ',' => sub { $cell[$cl_ptr] = ord( getc() ) },
    '[' => sub { jump_ahead() if $cell[$cl_ptr] == 0 },
    ']' => sub { jump_behind() if $cell[$cl_ptr] != 0 },
);

($disp{get_char()} or sub{})->() while 1;

    [download]
    We're building the house of the future together.
[reply]
[d/l]
      Another varation: 
      $cd .= $_ while <STDIN>;

sub jump_ahead {
        (($ch_ptr = index($cd, ']', $ch_ptr))) if (!$cell[$cl_ptr]);
}

sub jump_behind {
        (($ch_ptr = rindex($cd, '[', $ch_ptr))) if ($cell[$cl_ptr]);
}

while (1) {
        exit if ($ch_ptr == length($cd));
        $ch = substr($cd, $ch_ptr++, 1);

        ($ch eq '>') && $cl_ptr++;
        ($ch eq '<') && $cl_ptr--;
        ($ch eq '+') && $cell[$cl_ptr]++;
        ($ch eq '-') && $cell[$cl_ptr]--;
        ($ch eq '.') && (($_ = chr($cell[$cl_ptr])) && print);
        ($ch eq ',') && ($cell[$cl_ptr] = ord(getc));
        ($ch eq '[') && jump_head;
        ($ch eq ']') && jump_behind;
}

      [download]
      Although I prefer your version :)
[reply]
[d/l]
        Typo. s/jump_head/jump_ahead/
[reply]
Re: BF Interpreter
by locked_user mtve (Deacon) on Mar 09, 2006 at 09:33 UTC

    Dropping readable part, you may check results here, or this thread

    Also, does your interpreter support nested []?

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