From: Joseph Paish <jepaish@...>
Date: 2006-04-24T05:55:22+09:00
Subject: Re: how to ensure no blank lines in DATA statements

On Mon, 24 Apr 2006 00:42:15 +0900
dblack@wobblini.net wrote:

> Hi --
> 
> On Mon, 24 Apr 2006, Joseph Paish wrote:
> 
> > On Mon, 24 Apr 2006 00:20:46 +0900
> > dblack@wobblini.net wrote:
> >
> >> Hi --
> >>
> >> On Mon, 24 Apr 2006, Joseph Paish wrote:
> >>
> >>> suppose i have the following piece of code to read some data (input by
> >>> the user) following __END__
> >>>
> >>> while line = DATA.gets
> >>>  one_record = line.chomp!.split
> >>>  # do stuff
> >>>  end
> >>>
> >>>
> >>>
> >>> __END__
> >>>
> >>> bought 2 widgets 17.99
> >>> sold 12 widgets 22.49
> >>>
> >>> bought 11 things 12.99
> >>>
> >>> sold 5 things 10.49
> >>>
> >>>
> >>> as you can see, there is a blank line ahead of the first line of data (i
> >>> don't want that), and there may be one or more blank lines or lines
> >>> containing spaces after the data or even between the lines of data.
> >>>
> >>> i can't control what the user will do here, but i need to take it into
> >>> account.  any suggestions on how to ensure that any line i read contains
> >>> the 4 desired fields and doesn't contain anything else (even 4 blank
> >>> spaces like between the last bought and sold records)?
> >>
> >> Here's a nice way to avoid worrying about the spaces, though it may
> >> run aground if you have lines that have non-spaces and are malformed:
> >>
> >> require 'scanf'
> >>
> >> DATA.scanf("%s%d%s%f") do |action, num, item, price|
> >>    puts "#{action} #{num} #{item} at $#{price}, total $#{price * num}"
> >> end
> >>
> >> Output (with your sample):
> >>
> >> bought 2 widgets at $17.99, total $35.98
> >> sold 12 widgets at $22.49, total $269.88
> >> bought 11 things at $12.99, total $142.89
> >> sold 5 things at $10.49, total $52.45
> >>
> >>
> >> David
> >>
> >
> >
> > this is exactly what i needed.
> >
> > thank you
> >
> > joe
> 
> Do be careful, though, if there's a chance of a malformed line.  scanf
> will just stop.  But if the data are as they should be it will work
> nicely.
> 
> 
> David
> 

ok, thanks for the warning.  malformed lines *shouldn't* be an issue. 

in any event, it looks like it's time for some more reading (raise,
catch, throw, etc.) just to learn how to cover that possibility.

joe