Use DLL in excel-vba

Question

i would love to know how to declare and use a dll in vba. I have a code written in C and i would like to use some data from an excel sheet to test my c-code. How is it possible? Many thanks in advance

Answer 1

You have to declare the function in your VBA Module: For a Command:

[Public | Private] Declare Sub name Lib "libname" [Alias "aliasname"] [([arglist])]

For a Function Call:

[Public | Private] Declare Function name Lib "libname" [Alias "aliasname"] [([arglist])] [As type]

A few examples form one of my Apps:

Public Declare Function apiGetUserName Lib "advapi32.dll" Alias _
    "GetUserNameA" (ByVal lpBuffer As String, nSize As Long) As Long
Public Declare Function WM_apiGetDeviceCaps Lib "gdi32" Alias _
    "GetDeviceCaps" (ByVal hdc As Long, ByVal nIndex As Long) As Long
Declare Function WM_apiGetDesktopWindow Lib "user32" Alias _
    "GetDesktopWindow" () As Long
Declare Function WM_apiGetDC Lib "user32" Alias _
    "GetDC" (ByVal hwnd As Long) As Long
Declare Function WM_apiReleaseDC Lib "user32" Alias _
    "ReleaseDC" (ByVal hwnd As Long, ByVal hdc As Long) As Long
Declare Function WM_apiGetSystemMetrics Lib "user32" Alias _
    "GetSystemMetrics" (ByVal nIndex As Long) As Long
Declare Function GetComputerName Lib "kernel32" Alias "GetComputerNameA" _
    (ByVal lpBuffer As String, nSize As Long) As Long

Edited to Add PtrSafe information: See MSDN PtrSafe Language Reference

When running in 64-bit versions of Office Declare statements must include the PtrSafe keyword. The PtrSafe keyword asserts that a Declare statement is safe to run in 64-bit development environments. Adding the PtrSafe keyword to a Declare statement only signifies the Declare statement explicitly targets 64-bits, all data types within the statement that need to store 64-bits (including return values and parameters) must still be modified to hold 64-bit quantities using eitherLongLong for 64-bit integrals orLongPtr for pointers and handles.