Question

I’m trying to consume a DLL-located method in C#, which returns a dynamic array of structs. What ever I do, I receive the well-know “Object reference not set to an instance of an object” error, Here is my last code and it still tells that error:

string v_user = "kish";

        string v_pass = "u";

        string v_number = "p";

        string v_address = "url has been replaced with this string";

        string v_cid = "abc";

        Cls_SMS.SMSReceive.STC_SMSReceive[] xts;

        Cls_SMS.SMSReceive px = new Cls_SMS.SMSReceive();

   // *** is the below line

        xts = px.ExtendReceiveSMS(v_user, v_pass, v_number, v_address, v_cid);

        int upper_bound = xts.GetUpperBound(0);

        for (int counter = 0; counter < upper_bound; counter++)

        {

            Response.Write(xts[counter].Message.ToString());

            Response.Write("<br>");

        }

please note that my main problem is about receiving a dynamic array of structs with struct type name (Cls_SMS.SMSReceive.STC_SMSReceive) and other aspects such as connecting to the remote server is not my problem. I just want to allocate a dynamic array of vendor-defined structs to the left side of the assignment opeator in * line.

Please help me.
Thank you very much.

Answer 1

It is not clear how the px.ExtendReceiveSMS(v_user, v_pass, v_number, v_address, v_cid); method assigns the array, it probably doesn’t assign it at all because of the exception. Here’s how you could assign a dynamic array and return it:

public STC_SMSReceive[] ExtendReceiveSMS()
{
    STC_SMSReceive[] result = new STC_SMSReceive[2];
    result[0] = new STC_SMSReceive();
    result[1] = new STC_SMSReceive();
    return result;
}

Also if it is dynamic you might also take a look at List<T>:

public IList<STC_SMSReceive> ExtendReceiveSMS()
{
    IList<STC_SMSReceive> result = new List<STC_SMSReceive>();
    list.Add(new STC_SMSReceive());
    list.Add(new STC_SMSReceive());
    return result;
}