From: "Berger, Daniel" <djberge@...>
Date: 2004-01-16T01:28:23+09:00
Subject: NULL pointer given, Win32API

Hi all,

Windows XP
Ruby 1.8.1

How do I pass a straight-up string to a function in the Win32API?  I
understand how to pad a buffer store a value in a buffer, but not how to
convert a Ruby string to an LPCTSTR, for example.  I'm guessing that I
pack'd it wrong.

require "Win32API"
module Win32
	CloseEventLog = Win32API.new("advapi32","CloseEventLog","p","i")

	OpenEventLog  = Win32API.new("advapi32","OpenEventLog","pp","p")
	class EventLog
		def initialize(source,machine=0)
			lpSource = [source].pack("p")
			unless 0 == machine
				lpMachine = [machine].pack("p")
			end
			@h = OpenEventLog.call(source,machine)
			return @h
		end
		
		def close
			CloseEventLog.call(@h)
		end
	end
end

if $0 == __FILE__
   e = EventLog.new("Application") # results in "NULL pointer given"
   e.close
end

This is part of an effort to provide pure-ruby versions of the
win32utils code.  Please help.

Regards,

Dan