不计算小时，我怎么得到天差呢?

如何在不计算小时累积的情况下获得天数差异?下面是我尝试过的代码:

TimeSpan timeDifferenceLogin = (DateTime.Now).Subtract(lastTime);    
int dTimeDifferenceLogin = timeDifferenceLogin.Days;  
if (dTimeDifferenceLogin > 1)
{
    //MessageBox.Show("checkin_dayout");
    Out_Time.Text = "--:--";
    In_Time.Text = "--:--";
    btn_checkIn.Visibility = Visibility.Visible;
    btn_checkOut.Visibility = Visibility.Hidden;
    txtMessage.Text = "";
}
else if (dTimeDifferenceLogin < 1 && lastType == "out")
{
    //MessageBox.Show("checkout");
    DateTime lastInTime = absenList[lastData - 2].Time;
    In_Time.Text = lastInTime.ToString("HH:mm");
    Out_Time.Text = lastTime.ToString("HH:mm");
    btn_checkIn.Visibility = Visibility.Hidden;
    btn_checkOut.Visibility = Visibility.Hidden;
    txtMessage.Text = "See u tomorrow :D";
}

的例子:从星期二09:23:37开始，我想得到的结果是星期三00:00:00是新的一天，而不是我必须等待24小时，即星期三09:23:37。

我该怎么办?

var lastTime = new DateTime(2014,3,25);
var daydifference =  DateTime.Now.Date - lastTime.Date;