by Ross Garner, Independent Developer

...That can be Used by C, VB or other Applications.

I have been programming in VB for a number of years and have been tempted to write some of my code using C into a DLL for a couple of reasons:

• It should be faster
• It hides the source code, and therefore my intellectual property, from others if the code is to be incorporated into other projects

Unfortunately C seemed to be too hard and I never had the time, or courage, to try. When Delphi came along I thought this could be a solution to my dilemma. However the only Pascal I did was 15 years ago, so I had to go back to basics. Over the next 2 issues of the AVDF I will show the things I have learnt in making DLLs in Delphi and the interface code required for VB. I am sure there are Pascal gurus who could improve my code and I encourage you to participate in this discussion.

	The Different Ways of Passing Information
	Setting up the Delphi Environment
	A DLL Example for Numbers
	What Happens if it does not Work?
	Major Problems with Functions
	Adding Version Information to the DLL

In the next issue of Visual Developers Forum this topic will continue and show the way to transfer:

• pointers
• strings
• types arrays

If you have any comments or improvements please contact the editor via e-mail rgarner@vtrlmel1.oz.au, or phone 61-03 9818 6344.

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