[RESOLVED] Collection help[VB 2003.net]

[heeroyu16]

Hi guys/gals,

Hope you guys can help me on this
I'm trying to remove items from a collection if it has a duplicate from another collection
Do anyone knows how to do this?
I can use arraylist to replace it too
I have a code here which gives me error and i'm stuck on this

Collection A = getSno
Collection B = getnew

I want to check if getSno.item = getnew.items
remove

here's my current code

For b = getNew.Count - 1 To 0 Step -1
                        If getSno.Item(b) = getNew.Item(b) Then
                            getSno.Remove(getNew.Item(b))
                        End If
 
                        msg = Boxno & "," & getSno.Item(b)
                        olddate.Add(msg)
                        pretest codes")
              Next
                    dg1.DataSource = olddate
                    dg1.DataBind()

Thanks for your help guys/gals

[JAKSupport]

Here you go:

Dim a As ArrayList
        Dim b As ArrayList
 
        a = New ArrayList()
        'add some data
        a.Add("test")
        a.Add("test2")
 
        b = New ArrayList
        'add more data
        b.Add("foo")
        b.Add("test2")
 
        'loop using a
        'compare one item in a
        'to EVERY item in b
        'if a[i]=b[j] remove b[j]
        For i As Integer = 0 To a.Count - 1
            For j As Integer = 0 To b.Count - 1
                If a(i).ToString = b(j).ToString Then
                    'a[i] = b[j] in this case remove item from b
                    b.Remove(a(i).ToString)
                End If
            Next
        Next
 
        'what's left in b
        'you're left with the intersection of b
        'that is all elements in b that are not in a
        For k As Integer = 0 To b.Count - 1
            MsgBox(b(k).ToString())
        Next

[jmcilhinney]

If you get an error then you get an error message. What is it?

[JAKSupport]

I just can't understand why people who post dont understand we are not mind readers.
"My program errors out can you help"....ok how do we help if there is no error posted in the first place. This happens way too much in this forum.

<yoda> post the error you will, resolve the solution you shall </yoda>
<yoda> post the entire procedure you will, hand me your paycheck you shall </yoda>

How about a <yoda> tag ?

[heeroyu16]

Opps
I always thought you guys are jedi :P
Well JakSupport your codes do help out..

Oh the the error codes are Index out of range

I know my codes will have this error cause i'm not coding correctly which is why I posted to get help no?
I've just started learning scripting and not very good in it.And it is hard for me to describe what I don't know.

Anyway thanks alot

[jmcilhinney]

This bit removes the item at index 'b' (although in a rather peculiar way):

If getSno.Item(b) = getNew.Item(b) Then
    getSno.Remove(getNew.Item(b))
End If

then this bit tries to access the item at index 'b':

msg = Boxno & "," & getSno.Item(b)

which is the very item you just removed. Having said that, If you want to remove all items from a collection that also exist in another collection then you shouldn't be comparing items at the same index. This will work if there are no dulpicate entries in the first collection:

For Each item As String In clctn2
    If clctn1.Contains(item) Then
        clctn1.Remove(item)
    End If
Next item

This will work regardless:

For i As Integer = clctn1.Count - 1 To 0 Step -1
    If clctn2.Contains(clctn1(i)) Then
        clctn1.RemoveAt(i)
    End If
Next i

Both methods assume that the collections contain strings. If they don't then they would need some modification.

[heeroyu16]

Wow, u guys rock.
Both method work equally well.

Thanks again for your help.