string strA;
double dB;
//string轉換為double
string strA = t1.get_Parameter(BuiltInParameter.RBS_DUCT_BOTTOM_ELEVATION).AsValueString();
double dB = double.Parse(strA);
//double 轉換為string
dB = 234.345;
strA = dB.ToString();
//更多時候建議使用Decimal
string angle = Math.Abs(q.AsDouble() * 180 / Math.PI).ToString();
decimal needCheck = Decimal.Parse(angle);