From: Robert Klemme <shortcutter@...>
Date: 2007-12-22T05:10:03+09:00
Subject: Re: Binary file reading in Ruby

On 21.12.2007 15:34, rohit2000s@yahoo.com wrote:
> On Dec 21, 5:37 pm, Robert Klemme <shortcut...@googlemail.com> wrote:
>> 2007/12/21, rohit20...@yahoo.com <rohit20...@yahoo.com>:
>>
>>
>>
>>> Hi All,
>>> I am trying to read in a binary file of size 'n' using:
>>> mem_buf = IO.read(file_name, n, 0)
>>> Where file_name is an argument to the script.
>>> But after the read I observed that the size of the mem_buf is less
>>> than 'n' (It should be equal to 'n').
>>> (mem_buf.size != n).
>>> This script fails on the above read check.
>>> Any ideas what I might be doing wrong here. Any help will be
>>> appreciated.
>> Either, the file is smaller than n or you have an issue with
>> conversion (typically on Windows).  For binary files I'd do this which
>> is more portable:
>>
>> mem_buf = File.open(file_name,"rb") {|io| io.read}
>>
>> Also, it helps documenting things. Bw, you do not need the offset and
>> size arguments.
>>
>> Kind regards
>>
>> robert
>>
>> --
>> use.inject do |as, often| as.you_can - without end
> 
> Thanks a lot ! That was the exact problem I had - getting that part of
> code to work on windows.

You probably should have mentioned this. :-)

> Could you please take time to detail a bit on:
> 
> "{|io| io.read}" part of the code.

It's the block form of File.open and the return value of File.open in 
this case is the result of the block.

> Also is there a way to add the offset and size arguments to the read
> method that you suggested ?

http://ruby-doc.org/core/classes/IO.html#M002295

Cheers

	robert