Q66247: MENUITEMTEMPLATE Structure Is Documented Incorrectly

Article: Q66247
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.0,3.1
Operating System(s): 
Keyword(s): kbfile kbsample kbdocerr kb16bitonly kbMenu kbGrpDSUser kbOSWin310 kbOSWin300
Last Modified: 09-DEC-1999

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The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1 
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SUMMARY
=======

MenuTemp.exe is a sample program in that demonstrates how to use the
MENUITEMTEMPLATE structure and the LoadMenuIndirect() function.

The MENUITEMTEMPLATE structure is found in WINDOWS.H, which declares the
structure as follows:

     typedef struct
         {
         WORD    mtOption;
         WORD    mtID;
         char    mtString[1];
         } MENUITEMTEMPLATE;

Single-item arrays, such as mtString, provide a named field to use to access
memory. The actual text of the string is stored in the structure, not a pointer
to text stored elsewhere.

MORE INFORMATION
================

The following files are available for download from the Microsoft Download
Center:

MenuTemp.exe

For additional information about how to download Microsoft Support files, click
the article number below to view the article in the Microsoft Knowledge Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft used the most current virus detection software available on the date of
posting to scan this file for viruses. Once posted, the file is housed on secure
servers that prevent any unauthorized changes to the file.


The declaration of MENUITEMTEMPLATE in WINDOWS.H from the Windows SDK version 3.1
is correct. If a program attempts to assign an LPSTR to mtString, the C compiler
generates an error. Listed below is an erroneous code sample:

     MENUITEMTEMPLATE    mit;
     LPSTR               lpch;
     ...
     mit.mtString = lpch;
     ...

The mtString field is a 1-byte placeholder for the array. Because a LPSTR is 4
bytes long, it cannot be assigned to a 1-byte quantity.

The mtString[1] declaration in the structure serves as a placeholder for an
arbitrary number of characters. An application that uses the MENUITEMTEMPLATE
structure must allocate memory both for the template itself and the string that
is copied into mtString.

The following code sample demonstrates how an application might create a
MENUITEMTEMPLATE structure for a checked menu item having an ID value of 100 and
"&Menuitem" as its text:

  HANDLE              hMem;
     LPMENUITEMTEMPLATE  lpmit;
     static char         szMenuItem[] = "&Menuitem";

     ...

     // Note that the single char in the MENUITEMTEMPLATE structure
     // provides space for the null terminator on the string.
     hMem = LocalAlloc(LMEM_MOVEABLE, sizeof(MENUITEMTEMPLATE)
                                         + lstrlen(szMenuItem));

     // LocalLock function returns a near pointer;
     // no problem casting to a far pointer
     lpmit = (LPMENUITEMTEMPLATE)LocalLock(hMem);

     // Set the ID and the checked flag.
     lpmit->mtOption = MF_CHECKED;
     lpmit->mtID = 100;

     // Copy the menu item text.
     lstrcpy(lpmit->mtString, szMenuItem);

     ...

     // Make the following call, when a pointer is no longer needed.
     LocalUnlock(hMem);

     ...

     // Make the following call, when the MENUITEMTEMPLATE
     // is no longer needed.
     LocalFree(hMem);

     ...

Additional query words:

======================================================================
Keywords          : kbfile kbsample kbdocerr kb16bitonly kbMenu kbGrpDSUser kbOSWin310 kbOSWin300 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK300 kbWinSDK310
Version           : WINDOWS:3.0,3.1

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