In this blog Iíll show you how to use Windows API functions in Visual Report Writer.
We are using the function [B]PathFileExists[/B] exposed by the library Ď[B]Shlwapi.dll[/B] Ď
Visual Report Writer uses the [B]VARIANT[/B] type to communicate with the External Library Functions (ELF). Because of this Windows APIís canít be called directly, doing so will stop the rendering of the reports as Visual Report Writer expects a variant type to return and direct calling might even crash
In this blog, i'll show you how to make a function number2words for use in Visual Report Writer. We are creating a dynamic link library (DLL) containing useful routines that can be used by Visual Report Writer. Using External Library Functions (ELF) is a great way to extend the functionality of Visual Report Writer.
This walkthrough uses C and assumes you understand the fundamentals of the C language and Microsoft Visual Studio 2008.
[B]This blog covers the following:[/B]
We're continuing the back to the basics theme for advanced VDF developers by visiting the other side of [I]External_Function[/I]. If you haven't done so already, you should [URL="http://support.dataaccess.com/forums/blog.php?b=84"]read the first part[/URL], it's a prerequisite for understanding what I'm about to talk about here.
Let's start with a simple DLL written in C++, exporting only one silly function [I]SayHello()[/I], which we'll call from our VDF program. The finished
Let's take a closer look at [I]External_Function[/I]. But first, there are currently two generic and well established technologies you can use from VDF to interact with external components, DLL functions and COM objects. Actually, there are several other techniques available as well, the obsolete and defunct DDE technology, and the more modern SOAP technology for example, and various other IPC mechanisms. But we'll ignore those for now.
DLL and COM are the two fundamental technologies