From: Robert Klemme <shortcutter@...>
Date: 2007-09-17T06:20:03+09:00
Subject: Re: Newbie: what's Ruby idiom for word-by-word input?

On 16.09.2007 21:08, Alex Shulgin wrote:
> Hi,
> 
> What is the Ruby idiom for reading input word-by-word?  In other words
> -- how to process input while skipping all of the whitespace.
> 
> I would use this code in C++:
> 
> //std::istream& stream;
> while (!stream.eof())
> {
>     std::string str;
>     stream >> str;
>     ...
> }
> 
> Or something like this in C:
> 
> char str[100];  // please no flame on fixed buffer size :-)
> while (!feof(file))
> {
>     fscanf("%99s", str);
>     ...
> }
> 
> I have tried to use Ruby's scanf("%s") but found it severely broken
> (as per my task)--it discards the rest of the input up to the
> newline.  I currently use the following approach, which I find ugly:
> 
> while not $stdin.eof? do
>   words = $stdin.gets().scan(/[^\s]+/)
>   words.each do |w|
>      ...
>   end
> end
> 
> It takes me to write an inner loop and reads the entire string into
> memory and then splits it into array of words... Duh!
> 
> My application is not in any case a time- or memory-critical, nor did
> I measured to find the performance bottleneck... however, I desire for
> the enlightenment. :-)
> 
> Please show me the Ruby way!
> 
> 
> Cheers,
> Alex
> PS: Yes, I've searched the web, tutorials, FAQs, cookbooks, etc.
> before posting this.  No luck.

If you do not need to treat every word before it is read from the input 
you could do this:

$stdin.each do |line|
   line.scan /\w+/ do |word|
     puts word
   end
end

If your definition of "word" is different (i.e. non whitespace 
characters) you need a different regexp (for example /\S+/).

If you want to read to word boundaries only it becomes more difficult.

Kind regards

	robert