CRegKey::QueryValue

Call this method to retrieve the data for the specified value field of m_hKey. Earlier versions of this method are no longer supported and are marked as ATL_DEPRECATED.

LONG QueryValue( 
   LPCTSTR pszValueName, 
   DWORD* pdwType, 
   void* pData, 
   ULONG* pnBytes 
) throw( ); 
ATL_DEPRECATED LONG QueryValue( 
   DWORD& dwValue, 
   LPCTSTR lpszValueName  
); 
ATL_DEPRECATED LONG QueryValue( 
   LPTSTR szValue, 
   LPCTSTR lpszValueName, 
   DWORD* pdwCount  
);

Parameters

• pszValueName
  Pointer to a null-terminated string containing the name of the value to query. If pszValueName is NULL or an empty string, "", the method retrieves the type and data for the key's unnamed or default value, if any.

• pdwType
  Pointer to a variable that receives a code indicating the type of data stored in the specified value. The pdwType parameter can be NULL if the type code is not required.

• pData
  Pointer to a buffer that receives the value's data. This parameter can be NULL if the data is not required.

• pnBytes
  Pointer to a variable that specifies the size, in bytes, of the buffer pointed to by the pData parameter. When the method returns, this variable contains the size of the data copied to pData.

• dwValue
  The value field's numerical data.

• lpszValueName
  Specifies the value field to be queried.

• szValue
  The value field's string data.

• pdwCount
  The size of the string data. Its value is initially set to the size of the szValue buffer.

Return Value

If successful, returns ERROR_SUCCESS; otherwise, a nonzero error code defined in WINERROR.H.

Remarks

The two original versions of QueryValue are no longer supported and are marked as ATL_DEPRECATED. The compiler will issue a warning if these forms are used.

The remaining method calls RegQueryValueEx.

Security Note
This method allows the caller to specify any registry location, potentially reading data which cannot be trusted. Also, the RegQueryValueEx function used by this method does not explicitly handle strings which are NULL terminated. Both conditions should be checked for by the calling code.

Requirements

Header: atlbase.h

See Also

Reference

CRegKey Class

CRegKey::SetValue

Registry Value Types