#!ruby
# -*- mode: ruby; coding: utf-8 -*-
# Last updated: <2022/08/16 23:17:28 +0900>
#
# ffi sample. messagebox.
#
# winapi - What are the Ruby Win32API Parameters | How do I pass a null pointer? - Stack Overflow
# https://stackoverflow.com/q/8099694
#
# * Windows10 x64 21H2
# * Ruby 1.8.7 p330 i386-mswin32, i386-mingw32 + ffi 1.9.14 x86-mingw32
# * Ruby 1.9.3 p551 i386-mingw32 + ffi 1.9.14 x86-mingw32
# * Ruby 2.6.10 p210 i386-mingw32 + ffi 1.15.5 x86-mingw32 

require "rubygems"
require 'ffi'

module Win32
  extend FFI::Library
  ffi_lib "user32"
  attach_function :messageBox, :MessageBoxA, [:pointer, :string, :string, :long], :int
end

rc = Win32.messageBox(nil, "Hello World", "MessageBoxA by FFI", 0x40)
puts rc