Sometimes people assume that the default web browser is the program that is registered in the Windows registry to open files with an .html extension. However, it’s possible to set a default program to open .html files and another to open URL links that use the HTTP protocol.

The code below determines the default web browser for the HTTP protocol:

DWORD size = 256; HKEY hKey; int i, pos, len;TCHAR browserProgram[512], TCHAR buf[256];TCHAR *exeExtension = ".exe"; RegOpenKeyEx(HKEY_CLASSES_ROOT, _TEXT("http\shell\open\command"),  0, KEY_QUERY_VALUE, &hKey);RegQueryValueEx(hKey, NULL, NULL, NULL, (LPBYTE)buf, &size);RegCloseKey(hKey); if (buf[0] == _TEXT('"')) lstrcpy(browserProgram, &buf[1]);else lstrcpy(browserProgram, buf);len = lstrlen(browserProgram);pos = len - 4;for (i = 0; i < len - 3; i++) if (!strnicmp(&browserProgram[i], exeExtension, 4)) {  pos = i; break; }browserProgram[pos + 4] = _TEXT('');std::cout << browserProgram << std::endl;