From: Joe Van Dyk <joe.vandyk@...>
Date: 2004-11-20T06:33:11+09:00
Subject: Re: Extracting ints from a unsigned long

Joel VanderWerf wrote:
> 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]

Ah.... I didn't know that I needed to have the "C*" part.  Thanks.