Get a List of all SAP users

static ArrayList getUserList(string sign, string option, string low, string high)
    { 

        // Set your ERPConnect license
        LIC.SetLic("xxxx");

        // Open the connection to SAP
        using var connection = new R3Connection(
            host: "server.acme.org",
            systemNumber: 00,
            userName: "user",
            password: "passwd",
            language: "EN",
            client: "001")
        {
            Protocol = ClientProtocol.NWRFC,
        };

        connection.Open();    

        RFCFunction func = connection.CreateFunction("BAPI_HELPVALUES_GET");

        func.Exports["OBJTYPE"].ParamValue = "USER";
        func.Exports["METHOD"].ParamValue = "GETDETAIL";
        func.Exports["PARAMETER"].ParamValue = "USERNAME";

        RFCStructure shlp = func.Exports["EXPLICIT_SHLP"].ToStructure();
        shlp["SHLPNAME"] = "USER_ADDR";
        shlp["SHLPTYPE"] = "SH";

        RFCStructure sfh = func.Tables["SELECTION_FOR_HELPVALUES"].AddRow(); ;
        sfh["SELECT_FLD"] = "MC_NAMELAS";
        sfh["SIGN"] = sign;
        sfh["OPTION"] = option;
        sfh["LOW"] = low;
        sfh["HIGH"] = high;

        func.Execute();

        connection.Close();

        ArrayList user = new ArrayList();
        for (int i = 0; i < func.Tables["HELPVALUES"].RowCount; i++)
            {
                user.Add(func.Tables["HELPVALUES"].Rows[i, 0]);
            }
        if (user.Count == 0)
            {
                user.Add("No results matching criteria");
            }               

        return user;                           
    }

static void Main(string[] args)
    {
        ArrayList users = getUserList("I","CP","M*","");
        foreach (object userdetail in users)
            {
                Console.WriteLine(userdetail);
            }
        Console.ReadLine();
    }