HELP !!! WIth VB & DLL connection

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3 total messages Started by iti Wed, 27 Mar 1996 19:54

#67

Author: iti
Date: Wed, 27 Mar 1996 19:54

15 lines
1105 bytes

I have a DLL written in Visual C++ and am trying to write a Visual Basic (Ver. 
3) application to use it.  I am new to VB so I have two questions.

	1.  How can I access the message que (in order to do my own message 
processing) in a VB application?

	2.  I have a C DLL function declaired as 
"char far*   WINAPI    _export    MyFunct(void)  ".  How do I declare it in VB.

I would appreceate it if you can also answer me directly.  My E-Mail address is
iti@net.netvision.il

Thanks alot for all your help
Yaakov

Re: HELP !!! WIth VB & DLL connection

#72

Author: Helge Süß
Date: Tue, 09 Apr 1996 09:13

43 lines
2167 bytes

iti@Jerusalem.netvision.net.il wrote:
>
>I have a DLL written in Visual C++ and am trying to write a Visual Basic (Ver. >3) application to use it.  I am new to VB so I have two questions.
>
>	1.  How can I access the message que (in order to do my own message >processing) in a VB application?
>
>	2.  I have a C DLL function declaired as 
>"char far*   WINAPI    _export    MyFunct(void)  ".  How do I declare it in VB.
>

Declare Function MyFunct Lib "MyDll.DLL" As Long

You won't be happy with the char* though because VB Strings are handled
in a VERY different way. If you want to return a string result pass a
pointer to the function and a pre-initialized string at runtime.

e.g. int WINAPI _export MyFunct(char* result);

Declare Function MyFunct Lib "MyDll.DLL" (ByVal result As String) As Integer

(if you want to return a negative error code as function result in the int
or the length of the string if successful)

Then call it like this:

Dim ok As Integer
Dim resultstring As String

resultstring = "lotsofspacesuptothemaxyou'llexpect" & chr$(0)
ok = MyFunct(resultstring)
If ok >= 0 Then
    resultstring = Left$(resultstring, ok)
Else
   ' got some error to report
End If

Helge ;-)=)

----------------------------------------------------------
      (c) All Thoughts are Mine -- Genuine Genius
----------------------------------------------------------
helge@siemens.co.at        -----         VIENNA -- AUSTRIA
----------------------------------------------------------

Re: HELP !!! WIth VB & DLL connection

#73

Author: Helge Süß
Date: Tue, 09 Apr 1996 09:13

43 lines
2141 bytes

iti@Jerusalem.netvision.net.il wrote:
>
>I have a DLL written in Visual C++ and am trying to write a Visual Basic (Ver. >3) application to use it.  I am new to VB so I have two questions.
>
>	1.  How can I access the message que (in order to do my own message >processing) in a VB application?
>
>	2.  I have a C DLL function declaired as 
>"char far*   WINAPI    _export    MyFunct(void)  ".  How do I declare it in VB.
>

Declare Function MyFunct Lib "MyDll.DLL" As Long

You won't be happy with the char* though because VB Strings are handled
in a VERY different way. If you want to return a string result pass a
pointer to the function and a pre-initialized string at runtime.

e.g. int WINAPI _export MyFunct(char* result);

Declare Function MyFunct Lib "MyDll.DLL" (ByVal result As String) As Integer

(if you want to return a negative error code as function result in the int
or the length of the string if successful)

Then call it like this:

Dim ok As Integer
Dim resultstring As String

resultstring = "lotsofspacesuptothemaxyou'llexpect" & chr$(0)
ok = MyFunct(resultstring)
If ok >= 0 Then
    resultstring = Left$(resultstring, ok)
Else
   ' got some error to report
End If

Helge ;-)=)

----------------------------------------------------------
      (c) All Thoughts are Mine -- Genuine Genius
----------------------------------------------------------
helge@siemens.co.at        -----         VIENNA -- AUSTRIA
----------------------------------------------------------

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