Check out example codes for "dxf read c#". It will help you in understanding the concepts better.

Code Example 1

private void ReadDxfFile (string DxfFile)
{
    string Layer = "";

    string[] D = DxfFile.Split(new[] { Environment.NewLine }, StringSplitOptions.None);

    int iEntities = 0; for(int i = 0; i < D.Length; i++) { if (D[i] == "ENTITIES") {iEntities = i; break; } }
    for (int i = iEntities; i < D.Length; i++)
    {
        if (D[i] == "POINT" || D[i] == "AcDbPoint")
        {
            int iEntity = i; if (D[i].StartsWith("AcDb")) { for (iEntity = i; D[iEntity] != "AcDbEntity"; iEntity--) ; }
            Layer = ""; for (int iLayer = iEntity; iLayer < i + 10 && Layer == ""; iLayer++) { if (D[iLayer] == "  8") { Layer = D[iLayer + 1]; }; }
            for (int iWaarden = i; iWaarden < i + 8; iWaarden++)
            {
                if (D[iWaarden] == " 10" && D[iWaarden + 2] == " 20")
                {
                    //Here you can store the following data in a list for later use
                    //LayerName = Layer
                    //X = D[iWaarden + 1]
                    //Y = D[iWaarden + 3]
                    //Z = D[iWaarden + 5]
                }
            }
        }

        if (D[i] == "LINE" || D[i] == "AcDbLine")
        {
            int iEntity = i; if (D[i].StartsWith("AcDb")) { for (iEntity = i; D[iEntity] != "AcDbEntity"; iEntity--) ; }
            Layer = ""; for (int iLayer = iEntity; iLayer < i + 10 && Layer == ""; iLayer++) { if (D[iLayer] == "  8") { Layer = D[iLayer + 1]; }; }
            for (int iWaarden = i; iWaarden < i + 10; iWaarden++)
            {
                if (D[iWaarden] == " 10" && D[iWaarden + 2] == " 20")
                {
                    //Here you can store the following data in a list for later use
                    //LayerName = Layer
                    //Xbegin = D[iWaarden + 1]
                    //Ybegin = D[iWaarden + 3]
                    //Zbegin = D[iWaarden + 5]
                    //Xend = D[iWaarden + 7]
                    //Yend = D[iWaarden + 9]
                    //Zend = D[iWaarden + 11]
                }
            }
        }

        if (D[i] == "ARC" || D[i] == "AcDbArc" || D[i] == "AcDbCircle")
        {
            int iEntity = i; if (D[i].StartsWith("AcDb")) { for (iEntity = i; D[iEntity] != "AcDbEntity"; iEntity--) ; }
            Layer = ""; for (int iLayer = iEntity; iLayer < i + 10 && Layer == ""; iLayer++) { if (D[iLayer] == "  8") { Layer = D[iLayer + 1]; }; }
            for (int iWaarden = i; iWaarden < i + 10; iWaarden++)
            {
                if (D[iWaarden] == " 10" && D[iWaarden + 2] == " 20" && D[iWaarden + 10] == " 51")
                {
                    //Here you can store the following data in a list for later use
                    //LayerName = Layer
                    //Xmid = D[iWaarden + 1]
                    //Ymid = D[iWaarden + 3]
                    //Zmid = D[iWaarden + 5]
                    //Radius = D[iWaarden + 7]
                    //StartAngle = D[iWaarden + 9]
                    //StartAngle = D[iWaarden + 11]
                }
                if (D[iWaarden] == " 10" && D[iWaarden + 2] == " 20" && D[iWaarden + 12] == " 51")
                {
                    //Here you can store the following data in a list for later use
                    //LayerName = Layer
                    //Xmid = D[iWaarden + 1]
                    //Ymid = D[iWaarden + 3]
                    //Zmid = D[iWaarden + 5]
                    //Radius = D[iWaarden + 7]
                    //StartAngle = D[iWaarden + 11]
                    //StartAngle = D[iWaarden + 13]
                }
            }
        }

    }
}

Learn ReactJs, React Native from akashmittal.com