Argument Data Types
The data types used in C and C++, and the notation used to describe them, differ from those used in Microsoft® Visual Basic® for Applications (VBA). The following table describes some of the common data types used in DLL functions and their VBA equivalents:
| C/C++ data type | Hungarian prefix | Description | VBA equivalent |
|---|---|---|---|
| BOOL | b | 8-bit Boolean value. Zero indicates False; nonzero indicates True. | Boolean or Long |
| BYTE | ch | 8-bit unsigned integer. | Byte |
| HANDLE | h | 32-bit unsigned integer that represents a handle to a Microsoft® Windows® object. | Long |
| int | n | 16-bit signed integer. | Integer |
| long | l | 32-bit signed integer. | Long |
| LP | lp | 32-bit long pointer to a C or C++ structure, string, function, or other data in memory. | Long |
| LPZSTR | lpsz | 32-bit long pointer to a C-type null-terminated string. | Long |
Although you should be familiar with these data types and their prefixes, the Win32API.txt file mentioned earlier contains Declare statements ready for use in VBA. If you use these Declare statements in your code, the function arguments are defined already with the correct VBA data types.
For the most part, as long as you have defined and passed the correct data types, calling DLL functions works the same way as calling VBA functions. The exceptions are discussed in the following sections.
See Also
Calling DLL Functions | Returning Strings from DLL Functions | Passing User-Defined Types | Using the Any Data Type | Retrieving Error Information Following DLL Function Calls