Sorting a String list

Question

So i have created a program ,that takes a certain list of lines and reads the first 21 letters[Date - Time(01.02.2015 - 18:30:25)] from every line and split them. Now i want to check every line and and sort it depending on date (Newer to older).

What I have tried: I created a number from all date and time giving priority to Year>Month>Day>Hour>Minute>Second (Example: "01.02.2015 - 18:30:25" = 20150201183025) and then for every line that the program reads it reads also the previous(starting from the second line).

My sorting algorithm is:

Dim temp As String = ""
For i As Integer = 1 To Lines1.length
    If fNumber >= sNumber Then
        temp = Lines1(i - 1)
        Lines1(i - 1) = Lines1(i)
        Lines1(i) = temp
    End If
Next i

Lines1() is the array of strings that I want the program to check

fNumber is the Number from the Lines(i-1)

and sNumber is the Number from the Lines(i)

But my result is the exact same list with no changes.

Can anyone help?

Use DateTime.ParseExact to convert it to a date and then sort it — The One
– The One, Commented Jan 27, 2015 at 13:06
that is an array, not a List. there is not enough code to help. What is the declaration and where did fNumber come from. Probably ought to turn on Option Strict — Ňɏssa Pøngjǣrdenlarp
– Ňɏssa Pøngjǣrdenlarp, Commented Jan 27, 2015 at 13:07
If your goal is not to implement a sorting function but just get the sorting done, you would be better served using LINQ or learning how to use the built in Sort function. — crashmstr
– crashmstr, Commented Jan 27, 2015 at 13:32

sloth · Accepted Answer · 2015-01-27 13:18:43Z

3

Why do you try to sort the list by your own algorithm?

Let the framework handle that for you. Just convert the date information into a sane datatype (DateTime) and order it using OrderByDescending.

Example:

Dim Lines1 = {"01.02.2015 - 18:30:25",
              "01.06.2011 - 18:30:25",
              "11.02.2012 - 11:34:25",
              "01.07.2010 - 18:30:25",
              "01.01.2010 - 12:30:25"}

Dim c = System.Globalization.CultureInfo.InvariantCulture
Dim ordered = From s in Lines1
              Let dt = DateTime.ParseExact(s, "dd.MM.yyyy - HH:mm:ss", c)
              Order By dt Descending
              Select dt

ordered is now

enter image description here

answered Jan 27, 2015 at 13:18

sloth

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Comments

rory.ap · Accepted Answer · 2015-01-27 13:25:08Z

Here's an approach:

Function ParseSort(fromLines As String()) As List(Of String)
    ParseSort = New List(Of String)
    Dim sortingList = New List(Of KeyValuePair(Of Date, String))

    For Each line In fromLines
        Dim toParse = line.Substring(0, 21)
        Dim dateValue = Date.ParseExact(toParse, "MM.dd.yyyy - HH:mm:ss", Nothing)
        sortingList.Add(New KeyValuePair(Of Date, String)(dateValue, line))
    Next

    sortingList.Sort(New Comparison(Of KeyValuePair(Of Date, String))(Function(x As KeyValuePair(Of Date, String),
                                                                               y As KeyValuePair(Of Date, String)) Date.Compare(x.Key, y.Key)))

    For Each pair In sortingList
        ParseSort.Add(pair.Value)
    Next
End Function

This actually sorts using dates rather than treating your date string from each line as some number.

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