From: Logan Capaldo <logancapaldo@...>
Date: 2006-02-22T04:12:15+09:00
Subject: Re: Question about String.unpack


On Feb 21, 2006, at 9:28 AM, Eric Jacoboni wrote:

> Hi,
>
> Say i've a C struct like that:
>
> typedef struct {
>   char name[30];
>   double size;
>   int age;
>   char stuff;
> } enreg_t;
>
> This record is written in a file that i want to re-read with a Ruby
> script (just a toy example... to understand).
>
> I've not found a "clean" way to unpack such a record...
>
> My C compiler gives me a total sizeof of 48, so i use a
>   fd.sysread(48).unpack(A32dIC) to re-read. But that seems rather
>   'tricky' (i suppose we don't have always such a
>   information). Furthermore, the first element is completed with
>   garbage if the name field have less than 30 "useful" chars ("Doe",
>   for example).
>
> I'm sure i'm missing something but i've not managed to find the right
> way to do that.
>
> Any clue?
> --  
> Eric Jacoboni, ne il y a 1443970729 secondes
>

there isn't really a "clean" way to do this, since you are doing  
something inherently un-clean.
However, to fix the string issue, a possible solution is:

str.gsub!(/\000.*/, '')

assuming of course that name is a c-string.