wxWidgets iterate through registry entries - c++

Question

I am making a simple Application to collect and represent data over bluetooth serial COM port and I don't want to hard-code the COM ports. So I want to enumerate the COM ports by looking up HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM. However I'm fairly new to both wxWidgets and win32 registry terminology(I still don't understand what's supposed to be the "name" and "value" in wxWidgets documentation, they don't work as expected). What I want is to iterate through all the COMM ports and add them to a drop down list. This doesn't work:
wxRegKey regKey(wxRegKey::HKLM,"HARDWARE\\DEVICEMAP\\SERIALCOMM");
size_t subkeys;
long k = 1;
regKey.Open(wxRegKey::Read);
regKey.GetKeyInfo(&subkeys, NULL, NULL, NULL);
wxString key_name;
regKey.GetFirstValue(key_name, k);
m_drop_down->Append(key_name);
for (int i = 0; i < subkeys; i++) {
regKey.GetNextValue(key_name, k);
m_drop_down->Append(key_name);
}
regKey.Close();
It only appends one \Device\BthModem2 to the dropdown list. I would be grateful if someone cleared the terminologies up and tell me how I should go about making it work. For reference, here's what that registry entry looks to me, I want COM3, COM4, COM5, COM6 appended to the drop down list:

Answer 1

If you want to get the "value" (the thing in the right column), you can declare a function like this:
wxString GetStringData(const wxRegKey& regKey, const wxString& valueName)
{
wxRegKey::ValueType vtype = regKey.GetValueType(valueName);
wxString data;
if ( vtype == wxRegKey::Type_String )
{
regKey.QueryValue(valueName, data, true);
}
return data;
}
To get the complete list of them from the registry entry, you can iterate over the values in the registry entry like this:
while(regKey.GetNextValue(key_name, k)) {
wxString data = GetStringData(regKey,valueName);
if ( !data.IsEmpty() )
{
m_drop_down->Append(key_name);
}
}
GetNextValue will return false when there are no more values to be fetched breaking out of the loop.
This isn't really complete since this won't distinguish between a registry value whose type isn't string and a registy value whose type is a string but with empty data, but it should be clear how to modify the function and/or the iteration if it's necessary to make that distinction.

Answer 2

According to MSDN:Enumerating Registry Subkeys and RegGetValue, RegGetValue retrieves the type and data for the specified registry value.
Code:
int main()
{
long ret;
unsigned long reg_index = 0;
DWORD dwValSize = MAX_VALUE_NAME;
DWORD dwDataSize = MAX_VALUE_NAME;
LPTSTR lpValname = new TCHAR[MAX_VALUE_NAME]{};
LPTSTR lpDataname = new TCHAR[MAX_VALUE_NAME]{};
HKEY hkey;
int result = RegOpenKeyEx(HKEY_CURRENT_USER, TEXT("SOFTWARE\\Microsoft"), 0, KEY_READ, &hkey);
if (result == ERROR_SUCCESS) {
while ((ret = RegEnumValue(hkey, reg_index++, lpValname, &dwValSize, NULL, NULL, NULL, NULL)) != ERROR_NO_MORE_ITEMS)
{
if ((ret == ERROR_SUCCESS) || (ret == ERROR_MORE_DATA)) {
_tprintf(TEXT("(%d) %s"), reg_index, lpValname);
DWORD type = 0;
if (RegGetValue(hkey, 0,lpValname, RRF_RT_ANY, &type, lpDataname, &dwDataSize) == ERROR_SUCCESS)
{
_tprintf(TEXT("(Value data %s)\n"), lpDataname);
}
}
dwValSize = MAX_VALUE_NAME;
dwDataSize = MAX_VALUE_NAME;
ZeroMemory(lpDataname,sizeof(TCHAR)* dwDataSize);
ZeroMemory(lpValname,sizeof(TCHAR)* dwValSize);
}
RegCloseKey(hkey);
}
return TRUE;
}