使用TimeSpan对象，它是date减法的结果:

DateTime d1;
DateTime d2;
return (d1 - d2).TotalDays;

假设StartDate和EndDate是DateTime类型:

(EndDate - StartDate).TotalDays

如果有人想要作为双精度的天数(a, b类型的DateTime):

 (a.Date - b.Date).TotalDays

DateTime xmas = new DateTime(2009, 12, 25);
double daysUntilChristmas = xmas.Subtract(DateTime.Today).TotalDays;

对于a和b作为两个DateTime类型:

DateTime d = DateTime.Now;
DateTime c = DateTime.Now;
c = d.AddDays(145);
string cc;
Console.WriteLine(d);
Console.WriteLine(c);
var t = (c - d).Days;
Console.WriteLine(t);
cc = Console.ReadLine();

你可以试试这个

EndDate.Date.Subtract(DateTime.Now.Date).Days