vb.net - multi-dimension array list

Question

I've managed to make some single dimension array lists but I can't figure out a multi dimension arraylist.

Here's what I'm trying to do:

I have a database (mdb) with 5 columns that I want each row to be in an array list.

In PHP what I'd typically do is:

$array[$field1] = array($field2,$field3,$field4,$field5);

How I do the same in vb.net so anytime I need to fetch an item for a specific for the row1 I could call it?

For a single dimension I could do the following, but I can't figure out how to add more fields to a single array row:

    Dim tmpArrayX As New ArrayList
    tmpArrayX.Add(field(0))
    tmpArrayX.Add(field(1))
    etc...

Hans Olsson · Accepted Answer · 2010-09-08 09:50:21Z

18

If you want to use ArrayList, just make it's items contain other ArrayLists.

Or you could use normal arrays as:

Dim multiArray(2, 2) As String
multiArray(0, 0) = "item1InRow1"
multiArray(0, 1) = "item2InRow1"
multiArray(1, 0) = "item1InRow2"
multiArray(1, 1) = "item2InRow2"

Though my personal preference would be to use List as:

Dim multiList As New List(Of List(Of String))
multiList.Add(New List(Of String))
multiList.Add(New List(Of String))

multiList(0).Add("item1InRow1")
multiList(0).Add("item2InRow1")
multiList(1).Add("item1InRow2")
multiList(1).Add("item2InRow2")

Edit: How to find row:

Dim listIWant As List(Of String) = Nothing
For Each l As List(Of String) In multiList
    If l.Contains("item1InRow2") Then
        listIWant = l
        Exit For
    End If
Next

edited Sep 8, 2010 at 9:50

answered Sep 7, 2010 at 14:35

Hans Olsson

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8 Comments

Joe Over a year ago

That works, however how do I search for an item and return the index? Say I do: multiList(0).Add("item1InRow1") multiList(0).Add("item2InRow1") multiList(1).Add("item1InRow2") multiList(1).Add("item2InRow2") how do I search for "item1InRow2" and return the index # "1" so I can query the other columns in the array?

Hans Olsson Over a year ago

@Joe: Could just loop through it, I've added a simple sample to my answer above. Might be some neat Linq way as well, but I've not used that too much yet.

Behzad Over a year ago

What about a (2, 3) list? I can't implement it! Could you give an example about it? Thanks in advance.

Hans Olsson Over a year ago

@Behzad: Should just be to add another line as 'multiList(0).Add("item3InRow1")' under the other 2. Not sure if I understand your question though, would probably be better if you create a new question describing your exact problem (you could always link to this question to show the context).

Hans Olsson Over a year ago

@Behzad: Yes, within reason. There are some limitations so if you're going to store many millions of items it might be useful to read this question: stackoverflow.com/questions/7885294/…

|

JoeBob · Accepted Answer · 2017-03-20 15:52:34Z

4

' This allows adding rows on the fly....Tested and it works!

Dim multiList As New List(Of List(Of String))
Dim ListRow As Integer = 0

For each record in some_source 
  dim Country as string = record.country 'from some source 
  dim Date as Date = record.Date 'from some source 
  dim Venue as string = record.Venue 'from some source 
  dim Attendance as string = record.Attendance 'from some source 

  multiList.Add(New List(Of String))
  multiList(ListRow).Add(Country)
  multiList(ListRow).Add(Date)
  multiList(ListRow).Add(Venue)
  multiList(ListRow).Add(Rating)
  multiList(ListRow).Add(Attendance)
  ListRow = ListRow + 1
next

answered Mar 20, 2017 at 15:52

JoeBob

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