From: Joel VanderWerf <vjoel@...>
Date: 2004-11-19T08:05:21+09:00
Subject: Re: Extracting ints from a unsigned long

Joe Van Dyk wrote:
> I have a bunch of binary data consisting of 4 ints stored inside an unsigned
> long.
> 
> Here's psuedo C code to extract out the ints:
> 
> // data is a FILE pointer to the file
> unsigned long temp;
> fread(temp, sizeof(temp), 1, data);
> int first = temp >> 24;
> int second = temp << 8 >> 24;
> int third = temp << 16 >> 24;
> int fourth = temp << 24 >> 24;
> 
> 
> I'm trying to do the same thing in Ruby, but I'm having difficulties with
> the bitshifting.  Any ideas?  Would it make since to inline C code in Ruby
> for this?

irb(main):003:0> [1,2,3,4].pack "C*"
=> "\001\002\003\004"
irb(main):004:0> [1,2,3,4].pack("C*").unpack("C*")
=> [1, 2, 3, 4]