如何在命令解析器中检查空输入

在我的程序中，我必须解析用户的命令，然后执行适当的功能。但是，我想知道如何检查用户输入是否为空。如果为空，我会给他一条消息以正确输入命令。以下部分是我的命令解析器，它与scanf一起使用strcmp。

void CommandParser(const char* arg_computer_name)
{
    PrintColorful(2, "%s%s\n\n", "You are currently at c:\\", g_c_SystemModifiablePath);
    PrintColorful(0, "%s [%s%s] %s ", arg_computer_name, g_c_RootDrive, g_c_SystemModifiablePath, FM_CMD);

    while (scanf_s("%s", g_c_Commands, MAX_PATH - 1))
    {
        if (!strcmp(g_c_Commands, "help") || !strcmp(g_c_Commands, "?"))
        {
            FmShowHelpMessage();
        }

        else if (!strcmp(g_c_Commands, "version"))
        {
            FmShowProgramVersion();
        }

        else if (!strcmp(g_c_Commands, "cd"))
        {
            FmCommandChangeDirectory(arg_computer_name);
        }

        ...

        else
        {
            ErrorMessage("%s\n", "The command isn't supported.");
        }

        PrintColorful(0, "%s [%s%s] %s ", arg_computer_name, g_c_RootDrive, g_c_SystemModifiablePath, FM_CMD);
    }
}