You can call Pointer#null? to check if it is null
e.g.
if snapshot.null?
  return false
end


2009/9/8 Brett Blackham <brett.blackham@gmail.com>:

>
> I have the following code:
>
>  DWORD     = FFI::Type::UINT32
>  ...
>  ffi_lib 'kernel32'
>  attach_function :CreateToolhelp32Snapshot, [DWORD, DWORD], :pointer
>
>
>  snapshot = KERNEL32.CreateToolhelp32Snapshot
> ( Win32DebuggerDefines::TH32CS_SNAPTHREAD, @pid
>  if snapshot == nil
>    return false
>  end
>
>
>  However, this code fails at "if snapshot == nil". It appears that
> CreateToolhelp32Snapshot will always return a pointer. Even if @pid is
> not a valid process ID. Additionally, FFI pointers don't like to be
> compared to nil. Any thoughts on how I could test the results to
> ensure the CreateToolhelp32Snapshot call worked?
>
> Thanks
>
>
>
>
>
>
>