How To Programmatically Get VBRUN300.DLL Version Number (129875)

MORE INFORMATION

At address SS:0020 (Hex), Visual Basic will load the address of a function table when a Visual Basic program is running. This address is always fixed, although the address will depend on whether the program is run from the design environment or being run as an executable. VBRUN300.DLL contained in Version 3.0 always loads an address different from the version 4.0 equivalent. The following table details these addresses. The 16-Bit Hexadecimal address found at SS:0020 for a Visual Basic program:

   Mode                    Version 3.0    Version 4.0
   --------------------------------------------------
   Design/Run Mode         142E           39D2
   Run as Executable       01ED           1A90
				

These addresses are always fixed, so you can create a simple DLL to distinguish the versions of Visual Basic.

It is important to note that the addresses listed in this article will probably change in any future releases of Visual Basic. Therefore a control developer should account for the fact that the technique described below may provide incorrect results with any future releases.

Step-by-Step Example

1. Start a new project to make a DLL. In this example, Visual C++ version 1.52 was used as the compiler. First create a DEF file as below:

      LIBRARY              GetVersionVB
      DESCRIPTION          'GetVersion Can be called from Visual Basic'
      EXETYPE              WINDOWS 3.1
      CODE                 PRELOAD MOVEABLE DISCARDABLE
      DATA                 PRELOAD MOVEABLE SINGLE
      HEAPSIZE             4096
      EXPORTS
                           GetVersionVB @1
   
   						

2. Create a new source code file containing the following code. This code retrieves the address at SS:0020 (Hex) and compares it with the predefined values:

      #include <windows.h>
      #include <vbapi.h>
   
      int FAR PASCAL LibMain (HANDLE hInstance, WORD wDataSeg, WORD wHeapSize,
         LPSTR lpszCmdLine)
      {
         if (wHeapSize > 0)
            UnlockData (0);  //Unlocks the data segment of the library.
         return 1;
      }
   
      WORD FAR PASCAL _export GetVersionVB( void )
      {
         unsigned short nVerConst;
         nVerConst=VBGetVersion(); //Call VB API
   
         if (nVerConst==VB100_VERSION)  //Constant VB100_VERSION in vbapi.h
            return 1;
   
         if (nVerConst==VB200_VERSION)
            return 2;
   
         if (nVerConst==VB300_VERSION)
         {
   
            WORD SS20;
   
            _asm  {                 //Retrieve function table address at SS20
                  mov ax, SS:[0x0020];
                  mov SS20, ax;
                  }
   
            if ( (SS20==0x01ED) || (SS20==0x142E) )
            {
               return 3;
            }
   
            if ( (SS20==0x39D2) || (SS20==0x1A90) )
            {
               return 4;
            }
         }
   
         // If we reach this point, none of the addresses were correct
         // possibly indicating a new release of VB - so the code returns 0
   
        return 0;
      }
      int FAR PASCAL _export WEP(int nParam)
      {
         return 1;
      }
   						

3. Add the VBAPI.LIB to the list of libraries to be linked into the project. To accomplish this in Visual C++ version 1.52:
   
   
   1. Choose Project from the Options menu.
   2. Choose the Linker button.
   3. Select the Input category.
   4. Add VBAPI.LIB.
   5. Build the DLL, and name it FINDVER.DLL.
   6. Move FINDVER.DLL into the WINDOWS\SYSTEM directory.
4. Call the .DLL file from a Visual Basic program. To do this:
   
   
   1. Create a new project in Visual Basic. Form1 is created by default.
   2. Place the declaration for the DLL inside the Declarations section for the form:

            Declare Function GetVersionVB Lib "findver.dll" () As Integer
        
      								

   3. Place a command button (Command1) on Form1, and add the following code to the Command1_Click event to call the DLL function:

            MsgBox Str(GetVersionVB())
        
      								

   4. Press the F5 key to run the program, and click the Command1 button to see a message box listing the version of Visual Basic.