wym
asked on
Calling a C dll function with VB
I have written a C dll that exports functions that return LPXXX variables.
Eg:
LPMAPISESSION __stdcall GetSession();
void __stdcall CloseSession(LPMAPISESSION
I want to be able to call these functions from VB, so I declared them like this:
Private Declare Function GetSession Lib "lgkmapi.dll" () As Long
Private Declare Function CloseSession Lib "lgkmapi.dll" (ByVal lpSession As Long)
Private Sub Command1_Click()
Dim lpSession As Long
lpSession = GetSession()
MsgBox lpSession
CloseSession (lpSession)
End Sub
My problem is that I'm crashing on the CloseSession function.
I debug it through VC and I see that the value of lpSession returned from GetSession is 0x0168f108. From VB, the message box shows 23654664 was returned, which is the equivalent of 168f108 in hex.
When I debug the CloseSession function in VC, I see that I'm actually passing in 0x0063f3e8 for lpSession. How'd this happen? I have tried passing lpSession ByRef and ByVal in CloseSession but neither works.
Can anyone help solve this?
Eg:
LPMAPISESSION __stdcall GetSession();
void __stdcall CloseSession(LPMAPISESSION
I want to be able to call these functions from VB, so I declared them like this:
Private Declare Function GetSession Lib "lgkmapi.dll" () As Long
Private Declare Function CloseSession Lib "lgkmapi.dll" (ByVal lpSession As Long)
Private Sub Command1_Click()
Dim lpSession As Long
lpSession = GetSession()
MsgBox lpSession
CloseSession (lpSession)
End Sub
My problem is that I'm crashing on the CloseSession function.
I debug it through VC and I see that the value of lpSession returned from GetSession is 0x0168f108. From VB, the message box shows 23654664 was returned, which is the equivalent of 168f108 in hex.
When I debug the CloseSession function in VC, I see that I'm actually passing in 0x0063f3e8 for lpSession. How'd this happen? I have tried passing lpSession ByRef and ByVal in CloseSession but neither works.
Can anyone help solve this?
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Ark
What is typedef for LPMAPISESSION?
ASKER
Well, I found my problem was the fact that I was using an older version of my dll (in the same folder as my VB exe) and I should have given it an absolute path of my debug folder in my VC project when I stepped through in VC. (DOH!) But, I'm giving you the points because I learned something new about the dos prompt dumpbin which was neat.