用C#中的日期对字符串列表进行排序
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Sort string list with dates in C#
提问by
I have a List<string>with dates.
My list is:
我有一个List<string>日期。
我的清单是：
{"01/01/2013","10/01/2013","20/01/2013"}
I want to sort the list to look like this:
我想对列表进行排序，使其看起来像这样：
{"20/01/2013","10/01/2013","01/01/2013"}
How can I make this?
我怎样才能做到这一点？
采纳答案by mipe34
With linq:
使用 linq：
var list = new List<string> {"01/01/2013", "10/01/2013", "20/01/2013"};
var orderedList = list.OrderByDescending(x => DateTime.Parse(x)).ToList();
UPDATE (according questions in comments):
更新（根据评论中的问题）：
You can treat invalid dates like this (invalid date is there treated as default(DateTime)):
您可以像这样处理无效日期（无效日期被视为default(DateTime)）：
var list = new List<string> { "01/01/2013", "10/01/2013", "N/A" , "20/01/2013" };
var orderedList2 = list.OrderByDescending(x =>
{
DateTime dt;
DateTime.TryParse(x, out dt);
return dt;
});
Or if you want to have invalid datetime as first item in the list:
或者，如果您希望将无效日期时间作为列表中的第一项：
var orderedList3 = list.OrderByDescending(x =>
{
DateTime dt;
if (!DateTime.TryParse(x, out dt)) return DateTime.MaxValue;
return dt;
});
You can also filter the invalid dates out:
您还可以过滤掉无效日期：
var filteredList = list.Where(x =>
{
DateTime dt;
return DateTime.TryParse(x, out dt);
}).Select(DateTime.Parse).OrderByDescending(x => x);
Or even better:
或者甚至更好：
var filteredList = list.Select(x =>
{
DateTime dt;
return new {valid = DateTime.TryParse(x, out dt), date = dt};
}).Where(x => x.valid).Select(x => x.date).OrderByDescending(x => x);
回答by Dmitry Reznik
You shouldn't use string representations of data - we're all living in object-oriented world :)
你不应该使用数据的字符串表示——我们都生活在面向对象的世界:)
Best way would be to convert these strings into actual DateTime objects and sort them in reverse order via linq:
最好的方法是将这些字符串转换为实际的 DateTime 对象，并通过 linq 以相反的顺序对它们进行排序：
var dates = Array.ConvertAll(dateStrings, x => DateTime.Parse(x));
return dates.OrderByDesc(x => x);
Another way would be to implement custom sorting function, see this link. Then you'd just use it in a sort function:
另一种方法是实现自定义排序功能，请参阅此链接。然后你只需在排序函数中使用它：
DateAsStringComparer myComparer = new DateAsStringComparer();
dateStrings.Sort(myComparer);
回答by Simon Whitehead
Because they are the UK/AUS format (Day/Month/Year), you can sort them using OrderByDescending:
因为它们是 UK/AUS 格式（日/月/年），您可以使用OrderByDescending以下方式对它们进行排序：
List<string> dates = new List<string>() { "01/01/2013", "10/01/2013", "20/10/2013" };
foreach (var date in dates.OrderByDescending(x => x))
Console.WriteLine(date);
Personally I would convert them to DateTimeobjects first..
我个人会DateTime先将它们转换为对象..
回答by spajce
Why do you want to use List<string>instead of List<DateTime>?
为什么要使用List<string>而不是List<DateTime>？
List<DateTime> dates = ...
dates.OrderByDescending(c => c).ToList();
回答by Alex Filipovici
Try this:
尝试这个：
List<string> s = new List<string>() { "01/01/2013", "10/01/2013", "20/01/2013" };
var d = s.OrderByDescending(i => DateTime.ParseExact(i, "dd/MM/yyyy", null));
回答by Bravo Yeung
To convert DateTime string of custom format to stringof unified format, you can adopt following simple and safesnippet.
要将自定义格式的 DateTime 字符串转换string为统一格式，您可以采用以下简单和safe代码段。
string formatStr = "yyyyMMddHHmmss";
string result = Convert.ToDateTime(inputStr).ToString(formatStr);
Inside the code, formatStrcan be any possible forms the DateTimeclass can accept, you can set it as the format you need, here you can just use dd/MM/yyyywhich is matched with your target format string such as "20/01/2013".
在代码里面，formatStr可以是DateTime类可以接受的任何可能的形式，您可以将其设置为您需要的格式，在这里您可以使用dd/MM/yyyy与您的目标格式字符串匹配的格式，例如“20/01/2013”。
So for your case, the code can be simple as below:
因此，对于您的情况，代码可以很简单，如下所示：
List<string> list = new List<string> { "01/01/2013", "10/01/2013", "20/01/2013" };
var listAfterSorting = list.OrderByDescending(t =>
Convert.ToDateTime(t).ToString("dd/MM/yyyy")
.ToList());
While in some cases, using ParseExactto parse a data time string, it will throws error/exception String was not recognized as a valid DateTime, in that case if you turn to use TryParseExact, the result is probably default(DateTime)= 1/1/0001 12:00:00 AMbecause of parsing failed. Therefore, I do not recommend ParseExactor TryParseExact.
而在某些情况下，ParseExact用于解析数据时间字符串，它会抛出 error/exception String was not recognized as a valid DateTime，在这种情况下，如果您转向 use TryParseExact，结果可能是default(DateTime)=1/1/0001 12:00:00 AM因为解析失败。因此，我不推荐ParseExact或TryParseExact。
