计算两个时间相差的天数

private void button1_Click(object sender, EventArgs e)
        {
            string dateDiff = "";
            DateTime time2 =Convert.ToDateTime( "2014-01-15 00:00:00.000"); 
            TimeSpan ts1 = new TimeSpan(DateTime.Now.Ticks);
            TimeSpan ts2 = new TimeSpan(time2.Ticks);
            TimeSpan ts = ts1.Subtract(ts2).Duration();
            dateDiff = ts.Days.ToString();
            MessageBox.Show("日期之差是"+dateDiff);
        }