C / C++ / MFC

#define MAX_VALUE_NAME 255

// QueryKey - enumerates the subkeys of a given key and the associated 
//    values and then copies the information about the keys and values 
//    into a pair of edit controls and list boxes. 
// hDlg - dialog box that contains the edit controls and list boxes 
// hKey - key whose subkeys and values are to be enumerated 
 
VOID QueryKey(HWND hDlg, HKEY hKey) 
{ 
    CHAR     achKey[MAX_PATH]; 
    CHAR     achClass[MAX_PATH] = "";  // buffer for class name 
    DWORD    cchClassName = MAX_PATH;  // length of class string 
    DWORD    cSubKeys;                 // number of subkeys 
    DWORD    cbMaxSubKey;              // longest subkey size 
    DWORD    cchMaxClass;              // longest class string 
    DWORD    cValues;              // number of values for key 
    DWORD    cchMaxValue;          // longest value name 
    DWORD    cbMaxValueData;       // longest value data 
    DWORD    cbSecurityDescriptor; // size of security descriptor 
    FILETIME ftLastWriteTime;      // last write time 
 
    DWORD i, j; 
    DWORD retCode, retValue; 
 
    CHAR  achValue[MAX_VALUE_NAME]; 
    DWORD cchValue = MAX_VALUE_NAME; 
    CHAR  achBuff[80]; 
 
    // Get the class name and the value count. 
    RegQueryInfoKey(hKey,        // key handle 
        achClass,                // buffer for class name 
        &cchClassName,           // length of class string 
        NULL,                    // reserved 
        &cSubKeys,               // number of subkeys 
        &cbMaxSubKey,            // longest subkey size 
        &cchMaxClass,            // longest class string 
        &cValues,                // number of values for this key 
        &cchMaxValue,            // longest value name 
        &cbMaxValueData,         // longest value data 
        &cbSecurityDescriptor,   // security descriptor 
        &ftLastWriteTime);       // last write time 
 
//    SetDlgItemText(hDlg, IDE_CLASS, achClass); 
//    SetDlgItemInt(hDlg, IDE_CVALUES, cValues, FALSE); 
 
    SendMessage(GetDlgItem(hDlg, IDL_LISTBOX), 
        LB_ADDSTRING, 0, (LONG) ".."); 

	DWORD dwLength = MAX_PATH;
	
    // Enumerate the child keys, until RegEnumKeyEx fails. Then 
    // get the name of each child key and copy it into the list box. 

    SetCursor(LoadCursor(NULL, IDC_WAIT)); 
    for (i = 0, retCode = ERROR_SUCCESS; 
            retCode != ERROR_NO_MORE_ITEMS; i++) 
    { 
        retCode = RegEnumKeyEx(hKey, 
                     i, 
                     achKey, 
                     &dwLength, 
                     NULL, 
                     NULL, 
                     NULL, 
                     &ftLastWriteTime); 
        if (retCode != (DWORD)ERROR_NO_MORE_ITEMS) 
        {
            SendMessage(GetDlgItem(hDlg, IDL_LISTBOX), 
                LB_ADDSTRING, 0, (LONG) achKey); 
        }

		dwLength = MAX_PATH;
    } 
    SetCursor(LoadCursor (NULL, IDC_ARROW)); 
 
    // Enumerate the key values. 
    SetCursor(LoadCursor(NULL, IDC_WAIT)); 
 
    if (cValues) 
    {
        for (j = 0, retValue = ERROR_SUCCESS; 
                j < cValues; j++) 
        { 
            cchValue = MAX_VALUE_NAME; 
            achValue[0] = '\0'; 
            retValue = RegEnumValue(hKey, j, achValue, 
                &cchValue, 
                NULL, 
                NULL,    // &dwType, 
                NULL,    // &bData, 
                NULL);   // &bcData 
 
            if (retValue != (DWORD) ERROR_SUCCESS && 
                    retValue != ERROR_INSUFFICIENT_BUFFER) 
            { 
                wsprintf (achBuff, 
                    "Line:%d 0 based index = %d, retValue = %d, " 
                     "ValueLen = %d", 
                     __LINE__, j, retValue, cchValue); 
                MessageBox (hDlg, achBuff, "Debug", MB_OK); 
            } 
 
            achBuff[0] = '\0'; 
 
            // Add each value to a list box. 
            if (!lstrlen(achValue)) 
                lstrcpy(achValue, "<NO NAME>"); 
            wsprintf(achBuff, "%d) %s ", j, achValue); 
            SendMessage(GetDlgItem(hDlg,IDL_LISTBOX2), 
                LB_ADDSTRING, 0, (LONG) achBuff); 
        } 
	}
	SetCursor(LoadCursor(NULL, IDC_ARROW)); 
} 

CDialog::OnPaint();
HKEY key;
DWORD result;
RegCreateKeyEx(HKEY_CURRENT_USER, _T("Software"), NULL,
	NULL, REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, NULL, &key, &result);

ASSERT(REG_OPENED_EXISTING_KEY == result);

QueryKey(m_hWnd, key);
RegCloseKey(key);