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Accessing the windows registry.

Posted on 2000-04-09
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Last Modified: 2010-04-02
How can I delete a key (directory) from the windows registry? I mean, not a value, but a whole key. Please give the code and an example, if possible.

Thanks in advance.

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Question by:fcogilgo
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nietod earned 100 total points
ID: 2698038
RegDeleteKey().

There's not much to it.  You specify a handle to a parent key in the first parameter, and a strign that specifies the sub-key (of this parent key) that is to be deleted.

continues
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by:nietod
ID: 2698047
In windows NT the function will delete a key only if it does not have children.  The following example from the VC help shows how to write a recusive function that will delete a key with children   (I.e. it recusively deletes the children before deleting the parent.)
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LVL 22

Expert Comment

by:nietod
ID: 2698050
  // The sample code makes no attempt to check or recover from partial
   // deletions.
   //
   // A registry key that is opened by an application can be deleted
   // without error by another application in both Windows 95 and
   // Windows NT. This is by design.

   DWORD RegDeleteKeyNT(HKEY hStartKey , LPTSTR pKeyName )
   {
      DWORD   dwRtn, dwSubKeyLength;
      LPTSTR  pSubKey = NULL;
      TCHAR   szSubKey[MAX_KEY_LENGTH]; // (256) this should be dynamic.
      HKEY    hKey;

      // Do not allow NULL or empty key name
      if ( pKeyName &&  lstrlen(pKeyName))
      {
         if( (dwRtn=RegOpenKeyEx(hStartKey,pKeyName,
            0, KEY_ENUMERATE_SUB_KEYS | DELETE, &hKey )) == ERROR_SUCCESS)
         {
            while (dwRtn == ERROR_SUCCESS )
            {
               dwSubKeyLength = MAX_KEY_LENGTH;
               dwRtn=RegEnumKeyEx(
                              hKey,
                              0,       // always index zero
                              szSubKey,
                              &dwSubKeyLength,
                              NULL,
                              NULL,
                              NULL,
                              NULL
                            );

               if(dwRtn == ERROR_NO_MORE_ITEMS)
               {
                  dwRtn = RegDeleteKey(hStartKey, pKeyName);
                  break;
               }
               else if(dwRtn == ERROR_SUCCESS)
                  dwRtn=RegDeleteKeyNT(hKey, szSubKey);
            }
            RegCloseKey(hKey);
            // Do not save return code because error
            // has already occurred
         }
      }
      else
         dwRtn = ERROR_BADKEY;

      return dwRtn;
   }

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