HKEY hKey;
    char szPath[0x100];
    GetModuleFileName(NULL, szPath, sizeof(szPath));
    RegCreateKeyEx(HKEY_LOCAL_MACHINE,
        "Software\Microsoft\Windows\CurrentVersion\Run",
        NULL,
        "C:\test.exe",
        REG_OPTION_NON_VOLATILE,
        KEY_SET_VALUE,
        NULL,
        &hKey,
        NULL);
if (hKey)
{
    RegSetValueEx(hKey, "Test", NULL, REG_SZ, (LPBYTE)szPath, strlen(szPath));
    RegCloseKey(hKey);
}