Inputbox to array in VB.NET

Question

I have a program here that will solve an expression...

First I need to input the expression in a textbox. That will be stored in a CharArray and then substitute the variables to integer by using input boxes...

My problem is: How can I store the integer to an array and also store the operation?

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim arr() As Char = TextBox1.Text.ToCharArray
    Dim aChar As Char
    Dim a As String
    Dim calc() as String

    'Me.Height = Me.Height + 90
    Me.Button1.Enabled = False
    Me.TextBox1.Enabled = False
    For i = 0 To TextBox1.Text.Length() - 1
        aChar = arr.ElementAt(i)
        If Char.IsLetter(aChar) Then
            a = InputBox("Enter value for " & aChar, "Expression")

            'Here what code?
            '    Try
            '        calc(i) = a

            '    Catch ex As Exception
            '        MsgBox("eee")
            '    End Try
            'Else
        End If
    Next i
End Sub

Answer 1

I generally prefer to work with generic Lists, they make adding and removing items much easier. The code below should do what you need:

    Dim arr() As Char = TextBox1.Text.ToCharArray
    Dim aChar As Char
    Dim a As String
    Dim calc As New List(Of String)

    Me.Button1.Enabled = False
    Me.TextBox1.Enabled = False
    For i = 0 To TextBox1.Text.Length() - 1
        aChar = arr.ElementAt(i)
        If Char.IsLetter(aChar) Then
            a = InputBox("Enter value for " & aChar, "Expression")
            ''//Add the result to the list
            calc.Add(a)
        Else
            ''//Add the operator to the list
            calc.Add(aChar)
        End If
    Next i

    ''//If you want to convert to list to an array you can use this
    Dim CalcArray = calc.ToArray()

Answer 2

I haven't tested this or anything, but I think refactoring this a tad to use the For Each loop and either scoping or get rid of the a and aChar variables would be a little nicer approach:

    Dim arr() As Char = TextBox1.Text.ToCharArray
    Dim calc As New List(Of String)

    Me.Button1.Enabled = False
    Me.TextBox1.Enabled = False

    For Each aChar As Char In arr
        If Char.IsLetter(aChar) Then
            ''//Add the result to the list
            calc.Add(InputBox(String.Format("Enter value for {0} Expression", aChar.ToString)))
        Else
            ''//Add the operator to the list
            calc.Add(aChar.ToString)
        End If
    Next

    ''//If you want to convert to list to an array you can use this
    Dim CalcArray = calc.ToArray()