Variable issues in managed code (c#)?

[denimchicken]

I have a bit of managed code (c#) I'm working with to grab sim object data. It was working fine until I added a couple of more variables to my struct (it worked fine without the airline and flight number).

I'm pretty inexperienced when it comes to low level languages, so I'm having trouble seeing where I'm going wrong in this code. It's pretty apparent that I'm having issues with variable size or type due to some of the results I've been getting. I checked the variable formats against the documentation - the two I added are supposed to be string types. The marshal appears to be set properly to me - it matches my data types in the initDataRequest function.

Any ideas? Thanks.

my structure:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
struct Struct1
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public String atc_id;
public String atc_airline;
public String atc_fltnum;
public int squawk;
public double latitude;
public double longitude;
public double altitude;
public double groundv;
}

from the initDataRequest function:

simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "ATC ID", null, SIMCONNECT_DATATYPE.STRING256, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "ATC Airline", null, SIMCONNECT_DATATYPE.STRING256, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "ATC Flight Number", null, SIMCONNECT_DATATYPE.STRING256, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "Transponder Code:1", "BCO16", SIMCONNECT_DATATYPE.INT32, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "Plane Latitude", "degrees", SIMCONNECT_DATATYPE.FLOAT64, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "Plane Longitude", "degrees", SIMCONNECT_DATATYPE.FLOAT64, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "Plane Altitude", "feet", SIMCONNECT_DATATYPE.FLOAT64, 0.0f, SimConnect.SIMCONNECT_UNUSED);
simconnect.AddToDataDefinition(DEFINITIONS.Struct1, "Ground Velocity", "knots", SIMCONNECT_DATATYPE.FLOAT64, 0.0f, SimConnect.SIMCONNECT_UNUSED);

 

[WarpD]

The string variables don't just "return". Read up on SimConnect_RetrieveString.

 

[DragonflightDesign]

Now, Ed will probably tell me I'm wrong but I've found you need to MarshalAs on a per string basis

        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)>
        Public adf_ident As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)>
        Public adf_name As String
        <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=256)>
        Public nav_ident As String
(etc..)

and then .ToString the result

(...)
   frmMain.dgData(1, i).Value = avionics.adf_ident.ToString
  frmMain.dgData(1, i).Value = avionics.adf_name.ToString
  frmMain.dgData(1, i).Value = avionics.nav_ident.ToString
(...)

In this case the struct was called 'avionics' and I am writing the result to a datagrid.

Yes Ed, it's vb.Net


[Edit] If you can stand vb.Net, this is my test code based on the original Prepar3D example:

Dropbox - Error - Simplify your life

www.dropbox.com

I'm not guaranteeing it will make a lot of sense in places but it does grab the data you're after. It's very modularised, so it may take you ashort time to figure out what's going on.

 

[denimchicken]

Ah, thanks DragonflightDesign. I thought that the MarshalAs method would work for all strings in the structure. Didn't even think about that. Looking at the MarshalAs c# docs now, that very well could be it, and I'll report back when I get a chance to try it.

WarpD, I'm trying to follow the code, as it's a lot, especially without any real C++ experience. I'll keep reading. Thanks.

 

[WarpD]

Ah... sorry... didn't see it was C#... never use the stuff. Dai is correct... you have to define the MarshalAs for each string. I would think that should solve your issue.