Is there a way to query a registry key-name (not a value) from within a batch file?

Is there a way to query a registry key-name (not a value) from within a batch file?

I didn't know a way so here's a little C program to do it for you.

PROGRAM: RegKeyExists
PURPOSE: Allows one to determine if a registry key exists from a batch file.
The return value indicates if the key exists.
Return values
  1 - The key exists.
  0 - The key does not exist.
 -1 - The parameter was not valid.

USAGE:
  RegKeyExists 
   - The complete key to query. Do NOT surround parameters
               with spaces with quotes. Just type the key in as it
               appears in the registry editor.

Example Keys:
  HKCUSoftwareMicrosoftSourcesafeDatabases
  HKCR.act
  HKLMSoftwareMicrosoftWindows NTCurrentVersionAeDebug

  The first four characters of the argument indicate the section of
  the registry to look in:

  HKCR = HKEY_CLASSES_ROOT
  HKCC = HKEY_CURRENT_CONFIG
  HKCU = HKEY_CURRENT_USER
  HKLM = HKEY_LOCAL_MACHINE
  HKUR = HKEY_USERS
  HKPD = HKEY_PERFORMANCE_DATA
  HKDD = HKEY_DYN_DATA

  Any other values will cause a return of -1.

HISTORY:
  1.0 - August 6, 2001 - John Robbins (john@wintellect.com)

#include "stdafx.h"

HKEY ConvertPredefinedPart (TCHAR * szParam);

int _tmain (int argc, _TCHAR* argv[])
{ 
  // Do the simple check.
  if (argc < 2)
  {
      return (-1);
  }

  // Allocate a big buffer to hold all the command line parameters.
  // I need to concatinate them all together to account for spaces
  // in the list.
  TCHAR * szParam = new TCHAR [2048];
  szParam [0] = _T ('0');

  for (int i = 1; i < argc; i++)
  {
      _tcscat (szParam , argv[i]);
      if (i != (argc - 1))
      {
          // Plop a space between them.
          _tcscat (szParam , _T (" "));
      }
  }

  // Slide past the first five characters.
  TCHAR * szKey = _tcschr (szParam , _T ('\'));

  // No slash is a problem.
  if (NULL == szKey)
  {
      delete [] szParam;
      return (-1);
  }
  // Set the slash to NULL.
  *szKey = _T ('0');
  // Bump one past the slash.
  szKey++;

  // szParam points to the predefined key and szKey points to the
  // dynamic key.

  // The value I'll return.
  int iRet = -1;

  // Determine the predefined value.
  HKEY hPredefinedKey = ConvertPredefinedPart (szParam);
  if (0 != hPredefinedKey)
  {
      HKEY hKeyOpened = 0;

      // Try to open the key with the KEY_READ access, which is
      // the minimum read access necessary to check if the key
      // exists.
      LONG lRet = RegOpenKeyEx (hPredefinedKey, szKey, 0, KEY_READ, &hKeyOpened);

      if (ERROR_SUCCESS == lRet)
      {
          // Cool!  It opened, so it exists.

          // Always close anything you open/create.
          RegCloseKey (hKeyOpened);

          // Set the return value.
          iRet = 1;
      }
      else
      {
          // The key does not exist.
          iRet = 0;
      }
  }
   else
  {
      iRet = -1;
  }

  // Delete the memory.
  delete [] szParam;

  return (iRet);
}

HKEY ConvertPredefinedPart (TCHAR * szParam)
{
  HKEY hKey = 0;
  if (0 == _tcsicmp (szParam , _T ("HKCR")))
  {
      hKey = HKEY_CLASSES_ROOT;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKCC")))
  {
      hKey = HKEY_CURRENT_CONFIG;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKCU")))
  {
      hKey = HKEY_CURRENT_USER;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKLM")))
  {
      hKey  = HKEY_LOCAL_MACHINE;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKUR")))
  {
      hKey = HKEY_USERS;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKPD")))
  {
      hKey = HKEY_PERFORMANCE_DATA;
  }
  else if (0 == _tcsicmp (szParam , _T ("HKDD")))
  {
      hKey = HKEY_DYN_DATA;
  }
  return (hKey);
}

This was first published in August 2001

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