How To Read a DWORD From the Registry (258161)

MORE INFORMATION

1. From Visual FoxPro, create a program file (.prg) with the following code:

   #DEFINE HKEY_CLASSES_ROOT           -2147483648
   #DEFINE HKEY_CURRENT_USER           -2147483647
   #DEFINE HKEY_LOCAL_MACHINE          -2147483646
   #DEFINE HKEY_USERS                  -2147483645
   
   LOCAL nKey, cSubKey, cValue, nValueRead, lSuccess
   nKey = HKEY_CURRENT_USER
   cSubKey = "Software\Microsoft\Windows\CurrentVersion\Applets\Paint\Colors"
   cValue = "NumberOfColors"
   
   lSuccess = ReadRegDWORD(nKey, cSubKey, cValue, @nValueRead)
   
   IF (lSuccess) THEN
      =MESSAGEBOX("Function Successful. Value is: " + ALLTRIM(STR(nValueRead)))
   ELSE
      =MESSAGEBOX("Function Not Successful. Value is: " + ALLTRIM(STR(nValueRead)))
   ENDIF
   
   FUNCTION ReadRegDWORD
   * This function reads a REG_DWORD from the registry. It will return .T.
   * if successful and store the value in nValueRead. If not successful, it
   * will return .F. and nValueRead will contain -1.
      PARAMETERS  nKey, cSubKey, cValue,  nValueRead
      * nKey The root key to open. It can be any of the constants defined below.
      *#DEFINE HKEY_CLASSES_ROOT           -2147483648
      *#DEFINE HKEY_CURRENT_USER           -2147483647
      *#DEFINE HKEY_LOCAL_MACHINE          -2147483646
      *#DEFINE HKEY_USERS                  -2147483645
      *cSubKey The SubKey to open.
      *cValue The value that is going to be read.
      *nValueRead What was read from the registry
   
      * Constants that are needed for Registry functions
      #DEFINE REG_DWORD  4  && A 32-bit number.
   
      * WIN 32 API functions that are used
      DECLARE Integer RegOpenKey IN Win32API ;
         Integer nHKey, String @cSubKey, Integer @nResult
      DECLARE Integer RegQueryValueEx IN Win32API ;
         Integer nHKey, String lpszValueName, Integer dwReserved,;
         Integer @lpdwType, String @lpbData, Integer @lpcbData
      DECLARE Integer RegCloseKey IN Win32API Integer nHKey
   
      * Local variables used
      LOCAL nErrCode          && Error Code returned from Registry functions
      LOCAL nKeyHandle        && Handle to Key that is opened in the Registry
      LOCAL lpdwValueType     && Type of Value that we are looking for.
      LOCAL lpbValue          && The data stored in the value
      LOCAL lpcbValueSize     && Size of the variable
      LOCAL lpdwReserved      && Reserved Must be 0
   
      * Initialize the variables
      nKeyHandle = 0
      lpdwReserved = 0           
      lpdwValueType = REG_DWORD
      lpcbValueSize = 4          && DWORD is 4 bytes
      nValueRead = -1
      lpbValue = SPACE(4)
   
      nErrCode = RegOpenKey(nKey, cSubKey, @nKeyHandle)
      * If the error code isn't 0, then the key doesn't exist or can't be opened.
      IF (nErrCode # 0) THEN
         RETURN .F.
      ENDIF
   
      nErrCode=RegQueryValueEx(nKeyHandle, cValue, lpdwReserved, @lpdwValueType, @lpbValue, @lpcbValueSize)
      =RegCloseKey(nKeyHandle)
      IF (nErrCode # 0) THEN
         RETURN .F.
      ENDIF
   
      nValueRead = StrToLong(lpbValue)
   RETURN .T.
   
   FUNCTION StrToLong
      * This function converts a String to a Long
         PARAMETERS cLongStr
         LOCAL nLoopVar, nRetval
   
         nRetval = 0
         FOR nLoopVar = 0 TO 24 STEP 8
            nRetval = nRetval + (ASC(cLongStr) * (2^nLoopVar))
            cLongStr = RIGHT(cLongStr, LEN(cLongStr) - 1)
         NEXT
   RETURN nRetVal
   * End of Code
   					

2. Run the code created in step 1. A message box appears telling if the function was successful and what the value is.
3. You can replace nKey, cSubKey, and cValue with your information to be read from the registry.