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Old January 9th, 2008, 07:32 PM
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Default Go from 2d Array to 1d array without defining type

Hi,

I want to do something very easy, but I can't find a build in function
and i'm stuck with writing my own.

I'm trying to get a 1D array of column x out of a 2D array...
and that works for any type in the array.
example
Dim arr(0, 1) As Array ' Store Id + some sentence
Dim retArr(1) as array ' Get Ids only

arr(0,0) = 1
arr(0,1) = "rw1"

arr(1,0) = 2
arr(1,1) = "rw2"

retArr=getColumnFromArray(arr,1)

Code:
    Private Function getColumnFromArray(ByVal arr(,) As object, ByVal column As Byte) As Array
        Dim arrReturn() As VariantType
        Dim myType As Type = arr(0, 0).GetType()
        Dim i As Integer
        Dim len As Integer = UBound(arr, 0)

        ReDim arrReturn(len)

        For i = 0 To len
            arrReturn(i) = CType(arr(i, 0), myType)
        Next

        Return arrReturn
    End Function


and I get an error on the line
arrReturn(i) = CType(arr(i, 0), myType)

myType is not defined.

and why do I need an array of the Ids because:

The function that i'm writing loops through a filtered dataview
and get's all the ids. BUT I also want to store how many duplicate ids have been found!

So I ended up using a 2D array BUT I used the function 1Darray.BinarySearch to search for duplicate ids and that function only works for 1D arrays...

The problems came after I was reformatting my code so I could have the IdCount returned as well.
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Old January 10th, 2008, 11:13 AM
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Default

Which framework are you using? If you're using 2.0+ then this is a solution perfectly suited for Generics. You can build the method to require a type parameter such that the input and output is type specific. I haven't worked with generics in VB so I can't provide an immediate example.

-Peter
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