Sorting an array of dates

Question

I have created an array from a CSV of date values and now need to be able to sort them so that I can then get the latest date from the array.

I have tried:

Array.Sort()

but this doesn't sort correctly, I suppose because the array values are strings, any body got any ideas??

Thanks for any help.

CODE USED TO CREATE ARRAY

'array string exampel: "19/07/2012,23/07/2012,23/07/2012,19/07/2012,25/07/2012"
Dim ArrDates As Array = ArrDates .Split(",")

SOLUTION

Dim ArrAgentsReportCheck As Array = AgentsReportCheck.Split(",")

Dim ArrDates As New List(Of Date)
For i As Integer = 0 To ArrAgentsReportCheck.Length - 1
    ArrDates.Add(ArrAgentsReportCheck(i))
Next

ArrDates.Sort()
Dim LatestDate As Date = ArrDates.Max()

Create a List (not Array) of DateTime objects (not strings). You can use DateTime.TryParse/TryParseExact to convert the strings to DateTimes, and then use the Sort Method. — Adriaan Stander
– Adriaan Stander, Commented Aug 7, 2013 at 11:55
Show us an exemplary string that you want to convert to date. — Tim Schmelter
– Tim Schmelter, Commented Aug 7, 2013 at 11:55
Code used to load the array and the format of the strings (to be interpreted as dates) should be very helpful here — Steve
– Steve, Commented Aug 7, 2013 at 11:56
thanks for replies, added in example of dates string and how its converted to array. — Jammer
– Jammer, Commented Aug 7, 2013 at 12:09
As others have said make a List(of DateTime) instead and then you can use Max() on it to get the largest value (ie latest date). If getting the latest date is all you want then you don't need to sort the whole list so Max will be quicker. — Chris
– Chris, Commented Aug 7, 2013 at 12:21

Tim Schmelter · Accepted Answer · 2013-08-07 13:36:12Z

3

ArrDates = ArrDates.OrderBy(Function(d) DateTime.ParseExact(d, "dd/MM/yyyy", System.Globalization.CultureInfo.InvariantCulture)).ToArray()

Alternately, you can use OrderByDescending() depending upon your needs.

edited Aug 7, 2013 at 13:36

Tim Schmelter

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answered Aug 7, 2013 at 12:16

dotNET

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Comments

Shaikh Farooque · Accepted Answer · 2013-08-07 12:09:18Z

2

As astander said, It is very complicated to sort a array having datetime values. Instead just convert the array to List or ArrayList and make your life easy.

For ArrayList you can use the following syntax:

List<DateTime> dates = ... // init and fill
dates.Sort();
dates.Reverse();

answered Aug 7, 2013 at 12:09

Shaikh Farooque

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Comments

garf1eld · Accepted Answer · 2013-08-07 11:57:24Z

1

One way would be to convert strings to DateTime using DateTime.ParseExact

Another way just to write your own IComparer and pass to Array.Sort

answered Aug 7, 2013 at 11:57

garf1eld

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