文字列を高速に結合する

Imports System.Text

Public Class StringBuilderForm

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        '連結するデータを作成
        Dim arrData As New ArrayList

        For i As Integer = 1 To 10
            arrData.Add(i)
        Next

        '文字列を連結
        Dim sb As New StringBuilder("")

        '①普通に連結
        For Each s As String In arrData

            sb.Append(s)
        Next

        MessageBox.Show(sb.ToString)

        '②行単位で連結
        sb = New StringBuilder("")

        For Each s As String In arrData

            sb.AppendLine(s)
        Next

        MessageBox.Show(sb.ToString)

        '③書式を指定して連結
        sb = New StringBuilder("")

        For Each s As String In arrData
            sb.AppendFormat("No.{0}", s)
            sb.AppendLine()
        Next

        MessageBox.Show(sb.ToString)

        '④カンマ区切り（CSV）を作成
        sb = New StringBuilder("")
        For y As Integer = 0 To arrData.Count - 1
            For x As Integer = 0 To arrData.Count - 1
                sb.Append(y * x)
                sb.Append(",")
            Next

            '最後のカンマを改行文字に置換する
            sb.Replace(",", vbCrLf, sb.Length - 1, 1)
        Next

        MessageBox.Show(sb.ToString)
    End Sub
End Class

ツイート