LINQ To DataSet Samples - Conversion Operators

ToArray

This sample uses ToArray to immediately evaluate a sequence into an array.

Public Sub DataSetLinq54()
    Dim doublesDataTable = TestDS.Tables("Doubles").AsEnumerable()

    Dim doubles = From d In doublesDataTable _
        Select d!double

    Dim doublesArray = doubles.ToArray()

    Console.WriteLine("Every other double from highest to lowest:")
    For d = 0 To doublesArray.Length
        Console.WriteLine(doublesArray(d))
        d += 1
    Next
End Sub

Result:
Every other double from highest to lowest:
2
2
3

ToList

This sample uses ToList to immediately evaluate a sequence into a List(Of T).

Public Sub DataSetLinq55()
    Dim wordsTable = TestDS.Tables("Words").AsEnumerable()

    Dim words = From w In wordsTable _
        Select w!word

    Dim wordList = words.ToList()

    Console.WriteLine("The sorted word list:")
    For Each w In wordList
        Console.WriteLine(w)
    Next
End Sub

Result:
The sorted word list:
aPPLE
BlUeBeRrY
cHeRry

ToDictionary

This sample uses ToDictionary to immediately evaluate a sequence and a related key expression into a dictionary.

Public Sub DataSetLinq56()

    Dim scoreRecords = TestDS.Tables("ScoreRecords").AsEnumerable()

    Dim scoreRecordsDict = scoreRecords.ToDictionary(Function(sr) sr("Name"))
    Console.WriteLine("Bob's score: {0}", scoreRecordsDict("Bob")("Score"))
End Sub

Result:
Bob's score: 40

OfType

This sample uses OfType to return only the rows of the DataTable containing a value of type double.

Public Sub DataSetLinq57()
    Dim numbers = TestDS.Tables("MixedNumbers").AsEnumerable()

    Dim doubles = From n In numbers _
        Where TypeOf n!number Is Double _
        Select n

    Console.WriteLine("Numbers stored as doubles:")
    For Each d In doubles
        Console.WriteLine(d!number)
    Next
End Sub

Result:Numbers stored as doubles: 1 7