Extending the DBF Utility

User defined function DLL
To provide a way for the additional functions to be used such as any functions of your own, the DBF Utility can be extended by the use of a DLL. When it starts the utility looks for a DLL called VOPPDBFUDF.DLL, and if it finds it, loads it. (The name of this DLL can be changed in VOPP Plus!)

Initialising the DLL
This User Defined Function (UDF) DLL is a normal VO DLL, but needs to contain an initialisation function called _VOPPDLLRegister(). This function does not have to include any code, it is just need for VO to load the information from the DLL:

FUNCTION _VOPPDLLRegister

Functions in the DLL
Any functions you place in the DLL are accessible by the utility. If you use a user defined function in any of your index expressions you should also include the function in this DLL.

Sample UDF code
The DBF Utility and the calculator share the same format for the extension DLL. Sample code is provided in the file VOPP UDF.AEF in the VOPP3 directory.