Suppressing "Cannot Find MYDLL.DLL" Error Box

The information is this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows versions 3.0 and 3.1

SUMMARY

When explicitly loading a dynamic-link library (DLL) using LoadLibrary(), Windows will display a "file error" message box with the error

   Cannot find MYDLL.DLL

It is possible to suppress this error message so that a custom error message or other error handling may be implemented without this system error box. To do so, call SetErrorMode() with SEM_NOOPENFILEERRORBOX before the call to LoadLibrary(). LoadLibrary() will return error code 2 meaning "File was not found."

MORE INFORMATION

SetErrorMode() only affects the error mode of the current task and does not affect the entire system. The return value may be used to toggle the error mode in different portions of an application.

For an implicitly loaded DLL that may be missing, the system will display the aforementioned error box if the application is run from Program Manager. After clicking the OK button, the following message appears:

   Cannot find file d:\path\myexe.exe (or one of its components).
   Check to ensure the path and filename are correct and that
   all required libraries are available.

   File manager cannot find the specified file (or one of its
   components).

   Make sure the path and filename are correct and that all required
   libraries are available.

Sample Code

 {
 HINSTANCE hDLL;
 UINT uOldErrorMode;

 uOldErrorMode = SetErrorMode(SEM_NOOPENFILEERRORBOX);

 // Try to load DLL.
 hDLL = LoadLibrary("MYDLL.DLL");

 if (hDLL == 2)
    MessageBox(NULL, "MYDLL.DLL does not exist", "ERROR", MB_OK);
 else if (hDLL <= HINSTANCE_ERROR)
    MessageBox(NULL, "Other problems loading MYDLL.DLL, "ERROR", MB_OK);
 else
 {
    MessageBox(NULL, "MYDLL.DLL exists", "SUCCESS", MB_OK);
    FreeLibrary(hDLL);
 }

 SetErrorMode(uOldErrorMode);  // Can restore error mode if desired.
 }