Comments on: Octal, Hexadecimal, And Decimal Conversion

By: William Ward

William Ward — Tue, 08 Jul 2008 19:47:01 +0000

I think (s)printf is probably a lot more readable than using pack and unpack, though I suspect yours may be faster.

By: makjander

makjander — Tue, 08 Jul 2008 17:42:54 +0000

oops… hehe… i’ve run it now and see what you say it outputs, i’ve didn’t tested before
but you can change it using a workaround:

$number=5;
print unpack “B8″, (pack “J”, $number);

By: William Ward

William Ward — Tue, 08 Jul 2008 16:28:25 +0000

That doesn’t work the way you say. Did you run it?

When I run your program I get “00110101″ instead. Pack and unpack work on character strings, so 5 is really the string “5″ and 00110101 is the ASCII code for the “5″ character.

By: makjander

makjander — Tue, 08 Jul 2008 07:45:21 +0000

to convert a decimal number into binary it’s just even more easy: use UNPACK!!

for example:

$number=5;
print unpack “B8″, $number;

will output:
00000101

By: saurabh

saurabh — Mon, 14 Apr 2008 16:41:37 +0000

Oh sorry, never mind. oct converts from octal, i thought it was the string representation in octal of its arg.

By: saurabh

saurabh — Mon, 14 Apr 2008 16:39:26 +0000

> But there’s no bin() function in Perl. You have to use oct() with a “0b” prefix:
> $num = oct(“0b” . $bin);

And how exactly does that replace “bin()” (you know it’s converting binary to octal right)?

By: bharat

bharat — Thu, 27 Dec 2007 00:02:13 +0000

Thanks a lot to William Ward & Umut Topkara
This conversion had helped me a lot…

By: Praneel

Praneel — Tue, 03 Oct 2006 02:15:37 +0000

Nice piece of work. Exactly what I wanted.

By: William Ward

William Ward — Mon, 30 Jan 2006 06:26:32 +0000

Yes, I mentioned that above (the “%04o” example) but you explained it better. Thanks!

By: Umut Topkara

Umut Topkara — Mon, 30 Jan 2006 02:39:20 +0000

Hello,

Thank you for the helpful page. I’d like to contribute my 0.2 cents.

Sometimes you to format with leading 0s, e.g. when encoding URLs,
you need x0A rather than xA. For those cases you can use “%0numberx”
instead of “%0x” as the format string, and the sprintf will fill in
the necessary number of zeroes to make sure that the resulting string
is the specified number of characters.

Here’s how we could use this to encode strings for URLs:
perl -pe ‘s/([^a-zA-z])/”\%” . sprintf(“%02x”,ord($1))/eg’

You could use it to send files as thunderbird emails from command line:

cat email.txt | perl -pe ‘s/([^a-zA-z])/”\%” . sprintf(“%02x”,ord($1))/eg’ | xargs -iX thunderbird -compose ‘mailto:somebody@nowhere.net?subject=PerlHack&body=X’

Hope this would be helpful to someone.

-umut