C#中怎么计算两时间相差多少

label1.Text = "2004-1-1 15:36:05";
label2.Text = "2004-3-1 20:16:35";
DateTime d1 =new DateTime(2004,1,1,15,36,05);
DateTime d2 =new DateTime(2004,3,1,20,16,35);

TimeSpan d3 = d2.Subtract(d1);

label3.Text = "相差:"
+d3.Days.ToString()+"天"
+d3.Hours.ToString()+"小时"
+d3.Minutes.ToString()+"分钟"
+d3.Seconds.ToString()+"秒";