How To difference betwwen two dates

i enter date in text box choose by calander. but now i want to subract one text box date to other text box date value. my column name date data type is varchar. using code asp.net c#

I am giving a brief idea not actual code(check syntax)

DateTime dt1 = Convert.ToDateTime(TextBox1.Text);
DateTime dt2 = Convert.ToDateTime(TextBox2.Text);

you can use (dt1-dt2) or dt1.Subtract(dt2)

Thanks.....

if you are using vb.net then use can use datediff() function
datediff("d",date1,date2)