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Hex dump

by kschwab (Priest)
on Sep 10, 2001 at 19:08 UTC ( #111481=snippet: print w/ replies, xml ) Need Help??

Description: subroutine to print a hexdump of a string. I saw some discussion in the CB about needing such a thing.

Update: Also see HexView by OeufMayo.

sub hdump {
    my $offset = 0;
    foreach my $data (unpack("a16"x(length($_[0])/16)."a*",$_[0])) {
        if ($len == 16) {
            @array = unpack('N4', $data);
            $format="0x%08x (%05d)   %08x %08x %08x %08x   %s\n";
        } else {
            @array = unpack('C*', $data);
            $_ = sprintf "%2.2x", $_ for @array;
            push(@array, '  ') while $len++ < 16;
            $format="0x%08x (%05d)" .
               "   %s%s%s%s %s%s%s%s %s%s%s%s %s%s%s%s   %s\n";
        $data =~ tr/\0-\37\177-\377/./;
        printf $format,$offset,$offset,@array,$data;
        $offset += 16;

Update: Fixed the map() in a void context problem. Thanks merlyn. For the curious, it sort of evolved into a void context as I cleaned up the subroutine before posting it to perlmonks.
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Re: Hex dump
by merlyn (Sage) on Sep 11, 2001 at 02:01 UTC
    I really dislike the "void map" there, for things like:
    map {$_ = sprintf('%2.2x',$_)} @array;
    What's wrong with simply:
    $_ = sprintf "%2.2x", $_ for @array;
    It even comes in at fewer characters, as well as running faster!

    -- Randal L. Schwartz, Perl hacker

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