HOWTO: Determine the Version of a DLL

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b

SUMMARY

It is often necessary to determine the version of a .dll file on a user's system, such as when using the common controls. Determining the version of the Comctl32.dll file allows the developer to know, for instance, what functionality is available at run-time. This article demonstrates how to create and use the GetDllVersion() function to determine the version of a .dll file.

MORE INFORMATION

Visual FoxPro 6.0 offers the _fileversion FoxPro Foundation Class, which provides this functionality. Alternatively, the AGETFILEVERSION(ArrayName, cFileName) function can be used in Visual FoxPro 6.0. Visual FoxPro 5.0 can use the GetFileVersion() function in FoxTools. Users of Visual FoxPro 3.0 can use the following sample code to obtain the version of a .dll file. Note that this function only returns versions in a xx.xx.xxxx format. In other words, the file version in Windows Explorer might return a version of 4.72.2106.4, whereas GetDllVersion() only returns 4.72.2106.

Save the following program code to a .prg file and run the program:

Sample Code

   *-- Code begins here.

   *-- Platform IDs for DLLVERSIONINFO.
   *-- The Win32 defines are listed here, but cannot be used
   *-- with Visual FoxPro 3.0 because of the ten character limit.
   #define DLLVER_PLATFORM_WINDOWS         0x00000001      && Windows 95
   #define DLLVER_PLATFORM_NT              0x00000002      && Windows NT

   *-- For compatibility with VFP Visual FoxPro 3.0.
   #define WINDOWS         1      && Windows 95
   #define NT              2      && Windows NT

   lsReturn = GetDllVersion("comctl32.dll")

   *-- Parse the string.
   liMajorVersion = StrToLong(SUBSTR(lsReturn, 5, 4))
   liMinorVersion = StrToLong(SUBSTR(lsReturn, 9, 4))
   liBuildNumber  = StrToLong(SUBSTR(lsReturn, 13, 4))
   liPlatform     = StrToLong(SUBSTR(lsReturn, 17, 4))

   *-- Determine the platform.
   liOS = StrToLong(SUBSTR(lsReturn, 17, 4))
   IF liOS = WINDOWS
      lsPlatform = "Windows 9x"
   ELSE
      lsPlatform = "Windows NT"
   ENDIF

   lsVersionInfo = "Version: " + ;
     ALLTRIM(STR(liMajorVersion,5,0)) + "." + ;
     ALLTRIM(STR(liMinorVersion,5,0)) + "." + ;
     ALLTRIM(STR(liBuildNumber,5,0)) + CHR(10) + CHR(13) +;
     "Platform: " + lsPlatform

   =MESSAGEBOX(lsVersionInfo)

   *--------------------------------------------------------
   *-- Function:  GetDllVersion()
   *-- Summary:   Returns the version information for a DLL
   *-- Usage:     GetDllVersion(<cDllName>)
   *-- Example:   lsReturn = GetDllVersion("comctl32.dll")
   *--------------------------------------------------------
   FUNCTION GetDllVersion()
   PARAMETERS lsLib

   DECLARE LONG LoadLibrary IN kernel32.DLL STRING @lsLib
   DECLARE LONG GetProcAddress IN kernel32.DLL LONG, STRING lsFunction
   DECLARE LONG FreeLibrary IN kernel32.DLL LONG
   DECLARE LONG DllGetVersion IN (lsLib) STRING @DLLVERSIONINFO

   *-- DLLVERSIONINFO structure is 20 bytes.
   DLLVERSIONINFO = SPACE(20)
   hDll = LoadLibrary(@lsLib)
   IF hDll = 0
      RETURN ""
   ENDIF

   pDllVersion = GetProcAddress(hDll, "DllGetVersion")

   IF pDllVersion = 0
      RETURN ""
   ELSE
      lsSize = LongToStr(20)
      DLLVERSIONINFO = lsSize + SPACE(20 - LEN(lsSize))
      hResult = DllGetVersion(@DLLVERSIONINFO)
   ENDIF
   RETURN DLLVERSIONINFO

   ********************
   FUNCTION LongToStr()
   ********************
   * Passed : 32-bit non-negative numeric value (lnLongval)
   * Returns : ascii character representation of passed value in low-high
   * format (lcRetstr)
   * Example :
   *   m.long = "999999"
   *   m.longstr = long2str(m.long)

   PARAMETERS lnLongval

   PRIVATE i, lcRetstr

   lcRetstr = ""
   FOR i = 24 TO 0 STEP -8
      lcRetstr = CHR(INT(lnLongval/(2^i))) + lcRetstr
      lnLongval = MOD(lnLongval, (2^i))
   NEXT
   RETURN lcRetstr

   ********************
   FUNCTION StrToLong()
   ********************
   * Passed:  4-byte character string (lcLongstr) in low-high ASCII format
   * Returns:  long integer value
   * Example:
   * m.longstr = "1111"
   * m.longval = str2long(m.longstr)

   PARAMETERS lcLongstr

   PRIVATE i, lnRetval

   lnRetval = 0
   FOR i = 0 TO 24 STEP 8
      lnRetval = lnRetval + (ASC(lcLongstr) * (2^i))
      lcLongstr = RIGHT(lcLongstr, LEN(lcLongstr) - 1)
   NEXT

   RETURN lnRetval
   *-- Code ends here. 

REFERENCES

(c) Microsoft Corporation 1998. All Rights Reserved. Contributions by Mike
A. Stewart, Microsoft Corporation. 

Additional query words: kbVFp300b kbVFp500a kbVFp500 kbAPI

Keywords :
Version : WINDOWS:3.0,3.0b
Platform : WINDOWS
Issue type : kbhowto