Creating a list of element IDs and IFC GUIDs

So...I need a list of element IDs matched to their IFC GUIDs, but I'm not having much luck. I've tried piecing together a bit of what I know and what I've found, but I keep getting errors connected to the IDs : I can't get the element ID from an element, and I can't create the GUID to feed into an ifc converter. I imagine I'm making a total rookie mistake, as this is my first attempt to code in C#, but here you have it. The place I'm having problems is Suggestions?

Code:

---

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;

using Autodesk.Revit.DB;
using Autodesk.Revit.DB.Architecture;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;
using Autodesk.Revit.ApplicationServices;
using Autodesk.Revit.Attributes;
using Autodesk.Revit.DB.IFC.ExporterIFCUtils;

[TransactionAttribute(TransactionMode.Manual)]
[RegenerationAttribute(RegenerationOption.Manual)]

public class copyEverything : IExternalCommand
{

    //Set the path for the new text file
    string myPath = @"c:\temp\MyTest.txt";

    public Result Execute(
      ExternalCommandData commandData,
      ref string message,
      ElementSet elements)
    {

       
        //Get application and document objects
        UIApplication uiApp = commandData.Application;
        Document doc = uiApp.ActiveUIDocument.Document;



        var collector = new FilteredElementCollector(doc).WhereElementIsNotElementType()
            ;

        //Create a new text file and fill it with lines of elementIDs and IFC GUIDs, with a space in between
        using (StreamWriter myText = File.CreateText(myPath))
        {

            foreach (Element x in collector)
            {

///// ////////THIS IS WHERE I'M HAVING PROBLEMS///// ////////

                var elemId = GetElementId(x);
                var tempNum = CreateGUID(x);

///// ////////THIS IS WHERE I'M HAVING PROBLEMS///// ////////

                //Convert the GUID to IFC format, and add a new line to the text file
                var tempIfcId = IfcGuid.cv_to_64( tempNum );
                myText.WriteLine(elemId + " " + tempIfcId);
            }
        }
        return Result.Succeeded;
    }

    //Found function to convert GUID's into IFC's 64-bit scheme
    public static class IfcGuid
    {

        private static readonly char[] base64Chars = new char[]
        { '0','1','2','3','4','5','6','7','8','9'
        , 'A','B','C','D','E','F','G','H','I','J'
        , 'K','L','M','N','O','P','Q','R','S','T'
        , 'U','V','W','X','Y','Z','a','b','c','d'
        , 'e','f','g','h','i','j','k','l','m','n'
        , 'o','p','q','r','s','t','u','v','w','x'
        , 'y','z','_','$' };

        public static void cv_to_64(uint number, ref char[] result, int start, int len)
        {
            uint act;
            int iDigit, nDigits;

            Debug.Assert(len <= 4);
            act = number;
            nDigits = len;

            for (iDigit = 0; iDigit < nDigits; iDigit++)
            {
                result[start + len - iDigit - 1] = base64Chars[(int)(act % 64)];
                act /= 64;
            }
            Debug.Assert(act == 0, "Logic failed, act was not null: " + act.ToString());
            return;
        }
    }
}

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Is there any reason that you're not using the GUID that Revit assigns to every element?

You can retrieve the GUID of any element by accessing the element.UniqueId property

To retrieve the Element ID, you need to access the element.Id property. If you just want the numeric value of the ID, access the element.Id.IntegerValue property.