VB3 Diagnosing "Error in loading DLL" with LoadLibrary

- Standard and Professional Editions of Microsoft Visual Basic for

  Windows, versions 2.0 and 3.0

SUMMARY

The error "Error in loading DLL" (code 48) occurs when you call a dynamic-link library (DLL) procedure and the file specified in the procedure's Declare statement cannot be loaded. You can use the Microsoft Windows API function LoadLibrary to find out more specific information about why a DLL fails to load.

MORE INFORMATION

The API function LoadLibrary loads a DLL and returns either a handle or an error code. If the return value is less than 32, it indicates one of the errors listed below. A return value greater than or equal to 32 indicates success and you should call the FreeLibrary function to unload the library.

LoadLibrary Error Codes

 0 System was out of memory, executable file was corrupt, or
   relocations were invalid.

 2 File was not found.

 3 Path was not found.

 5 Attempt was made to dynamically link to a task, or there was a
   sharing or network-protection error.

 6 Library required separate data segments for each task.

 8 There was insufficient memory to start the application.

11 Executable file was invalid. Either it was not a Windows

   application or there was an error in the .EXE image.

13 Application was designed for MS-DOS 4.0.

14 Type of executable file was unknown.

15 Attempt was made to load a real-mode application (developed for

   an earlier version of Windows).

   containing multiple data segments that were not marked read-only.

   must be decompressed before it can be loaded.

   required to run this application was corrupt.

Steps to Create Example Program

The following program demonstrates how to call LoadLibrary to load a library and display a resulting error code.

1. Run Visual Basic for Windows, or from the File menu, choose New Project (press ALT, F, N) if Visual Basic for Windows is already running. Form1 is created by default.

2. Enter the following code into the general declarations section:

      Declare Function LoadLibrary Lib "kernel" (ByVal f$) As Integer
      Declare Sub FreeLibrary Lib "Kernel" (ByVal h As Integer)
   
   

3. Enter the following code into the Form Click event handler:

      Sub Form_Click ()
         Dim hInst As Integer
         ' Enter the name of your DLL file inside the quotes below.
         ' The file WIN.COM is not a valid DLL and demonstrates an error.
         hInst = LoadLibrary("win.com")
         If hInst > 32 Then
            MsgBox "LoadLibrary success"
            FreeLibrary (hInst)
         Else
            MsgBox "LoadLibrary error " + Format$(hInst)
         End If
      End Sub
   
   

4. Press the F5 key to run the program. Then click Form1. The program displays the error code returned from LoadLibrary. Look up this error code in the list of errors above to find an explanation.