From: William James <w_a_x_man@...>
Date: 2008-02-12T06:44:56+09:00
Subject: Re: Return number of matches

On Feb 11, 8:41 am, Jano Svitok <jan.svi...@gmail.com> wrote:
> On Feb 11, 2008 3:24 PM, Christopher Causer <chy.cau...@gmail.com> wrote:
>
> > This seems like an easy question but I cannot find any documentation on
> > it anywhere on the web.
>
> > I want to write a script that will count the number of dollars in a
> > string, excluding escaped dollars (ie. "\$".) My first hack was to use
> > split and count the number of elements in the array, but I came unstuck
> > trying to exclude \$. Surely there's a nice simple elegant solution?
>
> Easy solution: count $ and subtract \$ ;-)
>
> string.scan(/\$/).size - string.scan(/\\\$/).size
>
> It's possible to do it in one regex, but it won't be nice and elegant
> and I don't have the time now to try it...

That fails when the backslash preceding a $
is itself escaped.

>> irb --prompt xmp
string = "$\\\\$"
    ==>"$\\\\$"
string.scan(/\$/).size - string.scan(/\\\$/).size
    ==>1

Try this:

p DATA.read.scan(/(\\.|[$])/).flatten.grep(/^.$/).size

__END__
$\\$\$$