C# 为什么 DateTime.AddHours 似乎不起作用？
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Why DateTime.AddHours doesn't seem to work?
提问by user310291
I have same result 1338161400 when I do
当我这样做时，我得到了相同的结果 1338161400
DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
DateTime date = DateTime.Parse(@"28/05/12 01:30");
TimeSpan diff = date.ToUniversalTime() - origin;
Console.WriteLine( (Math.Floor(diff.TotalSeconds)).ToString());
as well as when I use date.AddHours(-4) :
以及当我使用 date.AddHours(-4) 时：
DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
DateTime date = DateTime.Parse(@"28/05/12 01:30");
date.AddHours(-4);
TimeSpan diff = date.ToUniversalTime() - origin;
Console.WriteLine( (Math.Floor(diff.TotalSeconds)).ToString());
I try to get 1338168600 like http://www.mbari.org/staff/rich/utccalc.htm
我尝试像http://www.mbari.org/staff/rich/utccalc.htm一样获得 1338168600
Update:
更新：
Thanks I changed to
谢谢我改成
DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
DateTime date = DateTime.Parse(@"28/05/2012 01:30");
date = date.AddHours(-4);
date = date.ToUniversalTime();
TimeSpan diff = date - origin;
Console.WriteLine((Math.Floor(diff.TotalSeconds)).ToString());
But I got 1338147000 still not 1338168600
但我得到 1338147000 仍然不是 1338168600
采纳答案by Slugart
Dates are immutable objects, i.e. they cannot be modified after creation. DateTime.AddHours returns a new DateTime instance which is shifted backwards by 4 hours but "date" will not be modified.
日期是不可变的对象，即它们在创建后不能被修改。DateTime.AddHours 返回一个新的 DateTime 实例，该实例向后移动 4 小时，但不会修改“日期”。
Use:
用：
DateTime newDate = date.AddHours(-4);
回答by Rawling
AddHoursreturns a newDateTimeobject which is the result of adding the hours onto the original. The original is left unchanged.
AddHours返回一个新DateTime对象，它是将小时添加到原始对象的结果。原件保持不变。
Thus you want date = date.AddHours(-4);instead of just date.AddHours(-4);
因此你想要date = date.AddHours(-4);而不是仅仅date.AddHours(-4);
回答by Lloyd Powell
AddHourssimply returns the new incremented date, use this :
AddHours简单地返回新的递增日期，使用这个：
date = date.AddHours(-4);
回答by Adam
回答by John Woo
The original date is set 4 hours backward but you didn't set it to new date. try this instead:
原始日期设置为向后 4 小时，但您没有将其设置为新日期。试试这个：
date = date.AddHours(-4);
回答by N73k
DateTime is not immutable. It's just that the DateTime methods don't change the struct, but instead return a new one.
日期时间不是一成不变的。只是 DateTime 方法不会更改结构，而是返回一个新结构。
If you do this:
如果你这样做：
DateTime d1 = DateTime.Now;
DateTime d2 = DateTime.Now;
d1 = d2;
Then, the struct d1 will be overwritten with d2's values.
然后，结构 d1 将被 d2 的值覆盖。
I don't know if it's possible to have an immutable struct.
我不知道是否有可能有一个不可变的结构。
回答by Sameeksha Kumari
Try if this works:
试试这是否有效：
System.DateTime today = System.DateTime.Now;
System.TimeSpan duration = new System.TimeSpan(0, 11, 0, 0);
System.DateTime answer = today.Add(duration);
System.Console.WriteLine("{0:dddd}", answer);
This seems to change the day in the date also on adding hours.
这似乎也会在增加小时数时更改日期中的日期。
