From: Kim Pedersen <kimersen@...>
Date: 2006-08-02T05:46:57+09:00
Subject: Binary numbers

Hi,

I have some data with binary numbers.
e.g. a 3 byte string could be 0x01216f which is 74095 decimal.
To do this conversion in ruby I've come up with:

def binum(bs)
    n = e = 0
    bs.reverse.each_byte do |c|
        n += c * 256 ** e
        e += 1
    end
    n
end

bs = ''
bs << 0x01 << 0x21 << 0x6f

puts binum(bs)  => 74095

Now some data are signed binary numbers stored as two's complement.
e.g. 0xfede91 which is -74095 decimal.

How can I do this conversion in ruby?

Best regards,
Kim