Perfoming multiple calculations in Calculator

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HI Everyone,

I've built this (very rudimentary) calculator and can't to do more than one operation at a time (5 +5 =10, 5+5+5=10) as it's only holding the last two numbers entered. I've tried using

VB

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
       ' Get the number, display the number, retun the focus
       Number1 = Number1 + Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "+"

   End Sub

But doesn't help, also tried quite a few other things. I haven't been able to find an answer and was hoping that someone could throw me a hint on this.

Here's most of the code:

VB

Dim Number1 As Double
   Dim Number2 As Double
   Dim Numberx As Double
   Dim conversion As Double
   Dim User As String
   Dim hasDecimal As Boolean
   Dim tmpValue As Double

   Private Sub frmCalculator_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load


   End Sub

   Private Sub buttons(sender As Object, e As EventArgs) Handles btn0.Click, btn1.Click, btn2.Click, btn3.Click, btn4.Click, btn5.Click, btn6.Click, btn7.Click, btn8.Click, btn9.Click
       If txtDisplay.Text = "" Then txtDisplay.Text = sender.text Else txtDisplay.Text = txtDisplay.Text & sender.text
       txtDisplay.Focus()
   End Sub

   Private Sub btnCE_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCE.Click
       ' Remove last entered number
       txtDisplay.Text = ""
       txtDisplay.Focus()
   End Sub

   Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
       ' Clear all numbers entered and held
       txtDisplay.Text = String.Empty : Number1 = 0.0 : Number2 = 0.0
       txtDisplay.Focus()
   End Sub

   Private Sub btnDecimal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDecimal.Click
       ' Add decimal point at point of insertion
       If InStr(txtDisplay.Text, ".") > 0 Then
           Exit Sub
       Else
           txtDisplay.Text = txtDisplay.Text & "."
       End If
   End Sub

   Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
       ' Get the number, display the number, retun the focus
       Number1 = Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "+"

   End Sub

   Private Sub btnSubtract_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubtract.Click
       ' Get the number, display the number, retun the focus
       Number1 = Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "-"
   End Sub

   Private Sub btnMultiply_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMultiply.Click
       ' Get the number, display the number, retun the focus
       Number1 = Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "*"
   End Sub

   Private Sub btnDivide_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDivide.Click
       ' Get the number, display the number, retun the focus
       Number1 = Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "/"

   End Sub


   Private Sub btnEquals_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEquals.Click
       Dim Result As Double
       Number2 = txtDisplay.Text

       ' Select math operatons
       Select Case User
           Case "+"
               Result = Number1 + Number2
               txtDisplay.Text = Result.ToString()
           Case "-"
               Result = Number1 - Number2
               txtDisplay.Text = Result.ToString()
           Case "/"
               Result = Number1 / Number2
               txtDisplay.Text = Result.ToString()
           Case "*"
               Result = Number1 * Number2
               txtDisplay.Text = Result.ToString()
           Case "x^"
               Result = Number1 ^ Number2
               txtDisplay.Text = Result.ToString()
           Case "1/x"
               Result = Number1 * 1 / 100
               txtDisplay.Text = Result.ToString()
           Case "PosNeg"
               Result = Number1 * -1
               txtDisplay.Text = Result.ToString()



       End Select

       txtDisplay.Text = Result.ToString()

   End Sub

I know that it's pretty Frankensteined up, but it's what I was able to come up with that works, Well, except for the fact that it won't perform more than one op at a time.

___________________________________________________________

Actually, using:

VB

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
       Number1 = Number1 + Val(txtDisplay.Text)
       txtDisplay.Text = ""
       txtDisplay.Focus()
       User = "+"

Works for the addition (5+6+9+4=24), but I can't figure out to handle the subtraction. I've put in many different types of

VB

 Private Sub btnSubtract_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubtract.Click
num1 - Val(txtDisplay.Text)

( +, -, +-, etc.) all give me a wrong result. Any help at all would be much appreciated!!

Posted 13-Dec-14 11:33am

Member 11139267

Updated 14-Dec-14 5:01am

v6

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Yvan Rodrigues · Answer 1 · 2014-12-13T12:39:00

From looking at your code it looks like it is running the way it was designed.

When I press 5 it is output to the TextBox.
When I press +, Number1 is set to 5; the TextBox is cleared.
I press 5 again and it is output to the TextBox.
When I press +, Number1 is set to 5; the TextBox is cleared. (again)
I press 5 again and it is output to the TextBox.
When I press =, Number2 is set to 5; The arithmetic addition operation is performed on Result = Number1 + Number2 = 10

Each time an operator button is pressed, you need to evaluate and update Result. Lets says there are 3 variables, Result, Number, and Operator.

Result = 0
(5 pressed) 
Number = 5

(+ pressed) 
Operator = +
Result = {Result==0} {Operator==+} {Number==5} = 5

(5 pressed) 
Number = 5

(+ pressed) 
Operator = +
Result = {Result==5} {Operator==+} {Number==5} = 10

(5 pressed) 
Number = 5

(= pressed) 
Operator = + (unchanged)
Result = {Result==10} {Operator==+} {Number==5} = 15

Yes, the way you have approached this problem is... interesting.

Instead of telling you what you did "wrong", I'll let you work on rethinking the problem and how it can be simplified and streamlined. :) It's part of becoming a better programmer. You should be able to reduce all of this to maybe 20 lines of code. Tip: Use Button.Tag to your advantage.