แจกโปรแกรม แม่สูตรคูณ VB2005 สาเหตุที่ทำเพราะอาจาราย์สั่งให้ทำ ทำนานมากเลย(สำหรับผม)

Public Class Form1
    Dim i, j, k, first, last, sum, numint As Integer
    Dim linelimit As Integer = 8
    Dim maxvalue As Integer = 25
    Dim strname, strint, strsum As String
    Dim check As Boolean
    Dim bypass As Boolean = False

    Sub warning()
        If bypass Then
            bypass = False
        Else
            MsgBox("โปรแกรมไม่สามารถคำนวณค่าที่ระบุได้")
            bypass = True
        End If
        btnSingle.Text = "แสดง"
        btnMulti.Text = "แสดง"
        txtint.Clear()
        txtShow.Clear()
    End Sub
    Sub conStruct()
        check = False
        Try
            numint = CInt(txtint.Text)
            check = True
        Catch ex As Exception
            warning()
        End Try

    End Sub

    Sub addZero()
        If i.ToString.Length = 1 Then
            strint = "0" & i
        Else
            strint = i
        End If
    End Sub

    Sub addZero2()
        If sum.ToString.Length = 1 Then
            strsum = "00" & sum
        ElseIf sum.ToString.Length = 2 Then
            strsum = "0" & sum
        Else
            strsum = sum
        End If
    End Sub

    Private Sub btnSingle_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSingle.Click

        conStruct()

        If check Then
            txtShow.Clear()
            For i = 1 To 12
                Try
                    sum = numint * i
                    addZero()
                    addZero2()
                    txtShow.Text &= numint & " x " & strint & " = " & strsum & vbCrLf
                Catch ex As Exception
                    i = 12
                    warning()
                End Try
            Next
        End If

    End Sub

    Private Sub btnMulti_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMulti.Click

        conStruct()

        If check Then
            check = False

            Select Case numint
                Case 2 To maxvalue
                    first = 2
                    last = numint
                    txtShow.Clear()
                    check = True
                Case maxvalue + 1 To 83
                    first = numint - (maxvalue - 2)
                    last = numint
                    txtShow.Clear()
                    check = True
                Case Else
                    warning()
            End Select

            If check Then
                For k = first To last Step linelimit
                    last = k + linelimit - 1
                    For i = 1 To 12
                        addZero()
                        If numint <= last Then
                            last = numint
                        End If

                        For j = k To last
                            Try
                                sum = i * j
                                addZero2()
                                txtShow.Text &= j & " x " & strint & " = " & strsum & "   "
                            Catch ex As Exception
                                j = last
                                warning()
                            End Try
                        Next
                        txtShow.Text &= vbCrLf
                    Next
                    txtShow.Text &= vbCrLf
                Next
            End If
        End If
    End Sub

    Private Sub txtint_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtint.TextChanged
        Try
            numint = CInt(txtint.Text)
            Select Case numint
                Case 2 To maxvalue
                    first = numint
                    btnMulti.Text = "แม่ 2 - " & numint
                Case maxvalue + 1 To 83
                    first = numint - (maxvalue - 2)
                    btnMulti.Text = "แม่ " & first & " - " & numint
                Case Else
                    btnMulti.Text = "Not Work"
            End Select
            btnSingle.Text = "แม่ " & numint
        Catch ex As Exception
            warning()
        End Try
    End Sub

    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Me.Close()
    End Sub
End Class

int[][] mul = new int[12][];
            string strOut = "";
             
            for (int i = 0; i <mul.Length;i++ )
            {
                mul[i] = new int[12];
                for (int j = 0; j < mul[i].Length; j++)
                {
                    mul[i][j] = (i + 1) * (j + 1);
                }
            }

            strOut += "ตารางสูตรคูณ"+"\n"+"\n";
            for (int i = 0; i < mul.Length; i++)
            {
                for (int j = 0; j < mul[i].Length; j++)
                {
                    strOut += mul[i][j].ToString();
                    if (mul[i][j] < 10) strOut += "      ";
                    else if (mul[i][j]<100) strOut += "    ";
                    else strOut += "  ";  
                }
                strOut += "\n";
            }
            MessageBox.Show(strOut);