From: "yermej@..." <yermej@...>
Date: 2007-10-26T01:17:11+09:00
Subject: Re: read write integer in binary into a file

On Oct 25, 9:36 am, Vianney Lecroart <ace...@gmail.com> wrote:
> Hello,
>
> I have some big files with lot of "unsigned int" (4 bytes) numbers and I
> want to read and write on these files.
>
> Currently, I found this to write:
>
> myfile << [mynum].pack("i")
>
> and to read:
>
> mynum = myfile.read(4).unpack("i").first
>
> I wonder if there's not something faster/simpler to do that without the
> need to convert the number into an array into a string to finally
> serialize it.
>
> Thank you.
> --
> Posted viahttp://www.ruby-forum.com/.

Do you have to deal with each number individually? Maybe you could
build up an array of numbers and then pack them all at once:

arr = []
while work_to_do do
  mynum = generate_next_number
  arr << mynum
end
myfile.write arr.pack('i*')

That way you aren't creating a new array for each number.

Similarly, for reading the file:
data = file.read
num_array = data.unpack('i*')

The '*' in (un)pack means to process the rest of the data in the same
way.