Hi Uri,

>I want to pass an LPRECT (long pointer to RECT struct) to an API function. What should I do? How can I fill in the values? How do I know how many bytes are needed for 32-bit LONG or 16-bit WORD data type?

You can do it either the hard way or the easy way. *g*

The hard way would be to convert the numbers to binary strings, concat them and pass the string by reference to the API function. The easy way would be a class that does this all for you. Mark Wilden and I wrote such a class some time ago. It's public domain and I could send you a copy if you want. When I find the time to finish the documentation I'll upload it to the library here.

With this struct component, the RECT struct would be implemented in VFP like this:

DEFINE CLASS RECT AS Struct
  Left = 0
  Top = 0
  Right = 0
  Bottom = 0
  cMembers = "l:Left,l:Top,l:Right,l:Bottom"
ENDDEFINE

And you can use it like this:

 oRect = NEWOBJECT("RECT")
 LPRECT = oRect.GetString()
 APIFunction(@LPRECT)
 oRect.SetString(LPRECT)
 ? oRect.Left, oRect.Top, oRect.Right, oRect.Bottom

Christof