CODEWITHSUNDEEP
vb.netdatatable
bluebox
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Reputation: 555

VB.NET DataTable - Getting the first "n" items of a column without using a loop

I have a DataTable dtand need to store the first n items of a certain column in an integer array. I know it's easy to do this with a loop like this: 

Dim array(n-1) As Integer
For i As Integer = 0 To n-1
    array(i) = dt.Rows(i).Item("columName")
Next

Nonetheless, is there a more convenient way to store these items in the array?

Upvotes: 0

Views: 2640

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460138

"Without using a loop" is impossible since there is no magic way to retrieve items from a collection without looping it. However, maybe you think that LINQ does not use loops:

Dim columNameValues = From row In dt
                      Select row.Field(Of Int32)("columName")
Dim array As Int32() = columNameValues.ToArray()

Gets all values from all rows, if you want to get n values use Enumerable.Take:

Dim array As Int32() = columNameValues.Take(n).ToArray()

In VB.NET you can even use Take in a LINQ query:

Dim first10Values = From row In dt
                    Select row.Field(Of Int32)("columName")
                    Take 10

For what it's worth, as Barry has mentioned it is technically possible to get n items from a collection without using a loop, but see yourself:

Dim value1 As Int32 = dt.Rows(0).Field(Of Int32)("columName")
Dim value2 As Int32 = dt.Rows(1).Field(Of Int32)("columName")
Dim value3 As Int32 = dt.Rows(2).Field(Of Int32)("columName")
' ..... '
Dim value10 As Int32 = dt.Rows(9).Field(Of Int32)("columName")

You could add them to a List(Of Int32), but that's just for demonstration purposes anyway.

Upvotes: 4

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