Microsoft KB Archive/137618

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PRB: CreateDialogIndirect Fails Under Windows 95

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Q137618

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The information in this article applies to:


 * Microsoft Win32 Software Development Kit (SDK), used with:
 * Microsoft Windows 95
 * Microsoft Windows 98
 * the operating system: Microsoft Windows 2000

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SYMPTOMS
Programs that use CreateDialogIndirect to create their dialog boxes at run time in Windows 95 may have trouble if the program has been ported from Windows NT or Windows 3.1.

CAUSE
The dialog resource for Windows 95 is the same as Windows NT; that is, all strings must be in Unicode, and all structures must be DWORD aligned.

Programs ported from Windows NT may find that when they insert strings into the dialog template resource, they used lstrcpyW to force the string to be Unicode or the program itself was called compiled for Unicode. However, lstrcpyW is not implemented in Windows 95, so it returns ERROR_NOT_IMPLEMENTED. To generate Unicode strings in Windows 95, the program must use MultiByteToWideChar.

Programs ported from 16-bit Windows 3.1 will probably have problems with the Unicode strings mentioned above and also with the structure alignment. In 16-bit Windows, dialog box resource structures are aligned on byte boundaries, so there's no work for the programmer to do. However, in Win32, all structures must be aligned on DWORD (four-byte) boundaries. AlignPtr is a simple helper routine that takes a pointer and returns the nearest pointer aligned on a DWORD boundary. The program should call this between all the dialog resource structures.

RESOLUTION
Use MultiByteToWideChar to generate Unicode strings in Windows 95, and call AlignPtr, which takes a pointer and returns the nearest pointer aligned on a DWORD boundary, between all the dialog resource structures to align all structures on DWORD boundries.

STATUS
This behavior is by design.

Sample Code
  // // AlignPtr - Helper routine. Take an input pointer, return closest // pointer that is aligned on a DWORD (4 byte) boundary. //

LPWORD AlignPtr (LPWORD lpIn) {

ULONG ul;

ul = (ULONG) lpIn; ul +=3; ul >>=2; ul <<=2; return (LPWORD) ul;

} Additional query words: porting CreateDialogIndirectParam

Keywords : kbDlg kbOSWin2000 kbResource kbSDKWin32 kbGrpDSUser kbOSWin95 kbOSWin98

Issue type : kbprb

Technology : kbWin32SDKSearch kbAudDeveloper kbSDKSearch kbWin32sSearch