Making a string that adapts itself to the text inside it - vb.net

Question

I'm making a program to solve second grade equations (e.g. 2x²+2x+2) and I was trying to have the user input the whole equation in a single text box. The computer then stores what has been typed into the text box in a string, and then it parses the string to find the coefficents. For an equation like 2x²+2x+2, the coeficients are 2, 2 and 2 and they are stored in the string at locations 0, 4 and 7. The big problem is, what if it's a bigger equation like 32x²+32x+45 or 123x²+45x+6? My logic won't work in that case. Does anyone know how to do it?
Here's my code that only works for the small equations:
Public Class Form1
Dim i1 As Double
Dim i2 As Double
Dim i3 As Double
Dim delta As Double
Dim x1 As Double
Dim x2 As Double
Dim leters As String
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
i1 = T1.Text
i2 = T2.Text
i3 = T3.Text
delta = (i2 * i2) - 4 * (i1 * i3)
If (delta < 0) Then
Ld.Text = delta
L1.Text = "Impossível"
L2.Text = "Impossível"
Else
x1 = (-i2 + Math.Sqrt(delta)) / (2 * i1)
x2 = (-i2 - Math.Sqrt(delta)) / (2 * i1)
Ld.Text = delta
L1.Text = x1
L2.Text = x2
End If
End Sub
Private Sub RadioButton1_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles RadioButton1.CheckedChanged
GroupBox1.Text = "Equação"
GroupBox1.Width = 200
GroupBox1.Height = 58
T1.Width = 188
T3.Hide()
T2.Hide()
Label1.Hide()
Button1.Hide()
Button2.Show()
End Sub
Private Sub RadioButton2_CheckedChanged(sender As System.Object, e As System.EventArgs) Handles RadioButton2.CheckedChanged
GroupBox1.Text = "Coeficientes"
GroupBox1.Width = 200
GroupBox1.Height = 143
T1.Width = 119
T3.Show()
T2.Show()
Label1.Show()
Button1.Show()
Button2.Hide()
End Sub
Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
leters = T1.Text
leters.ToString()
End Sub
End Class

Answer 1

You could use RegEx to parse the string, which would be nice because you could change the RegEx expression as a setting without rebuilding your assembly. However, if the equation string format is always going to be the same, as appears to be the case here (because the rest of the code would fail if it weren't), then you could simply use String.Split to parse the string. For instance:
Dim equation As String = "32x²+32x+45"
Dim parts() As String = equation.Split(New Char() {"+"c, "x"c}, StringSplitOptions.RemoveEmptyEntries)
Dim coefficient1 As Integer = Integer.Parse(parts(0))
Dim coefficient2 As Integer = Integer.Parse(parts(2))
Dim coefficient3 As Integer = Integer.Parse(parts(3))