(help) basic calculator in vb 2008

[jckryan157]

Hello. I am new to visual basic 2008, and i started with simple project-calculator. I made it to the point where "+" sign works, and "=" sign execute the command of "+" sign. Now i try to make "-" sign work: the problem is, idk how to bind it with "=". Here is the code:

Public Class Form1
    Dim total1 As Integer
    Dim total2 As Integer
 
    Private Sub btnOne_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOne.Click
        txtDisplay.Text = txtDisplay.Text & btnOne.Text
    End Sub

    Private Sub btnTwo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTwo.Click
        txtDisplay.Text = txtDisplay.Text & btnTwo.Text
    End Sub

    Private Sub btnThree_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnThree.Click
        txtDisplay.Text = txtDisplay.Text & btnThree.Text
    End Sub

    Private Sub btnFour_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFour.Click
        txtDisplay.Text = txtDisplay.Text & btnFour.Text
    End Sub

    Private Sub btnFive_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFive.Click
        txtDisplay.Text = txtDisplay.Text & btnFive.Text
    End Sub

    Private Sub btnSix_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSix.Click
        txtDisplay.Text = txtDisplay.Text & btnSix.Text
    End Sub

    Private Sub btnSeven_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSeven.Click
        txtDisplay.Text = txtDisplay.Text & btnSeven.Text
    End Sub

    Private Sub btnEight_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEight.Click
        txtDisplay.Text = txtDisplay.Text & btnEight.Text
    End Sub

    Private Sub btnNine_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNine.Click
        txtDisplay.Text = txtDisplay.Text & btnNine.Text
    End Sub

    Private Sub btnZero_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnZero.Click
        txtDisplay.Text = txtDisplay.Text & btnZero.Text
    End Sub

    Private Sub cmdPlus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdPlus.Click
        total1 = total1 + Val(txtDisplay.Text)
        txtDisplay.Clear()
    End Sub

    Private Sub cmdEquals_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdEquals.Click
        total2 = total1 + Val(txtDisplay.Text)
        txtDisplay.Text = total2
        total1 = 0

    End Sub

    Private Sub cmdClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdClear.Click
        txtDisplay.Clear()
    End Sub

   
    Private Sub cmdMinus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdMinus.Click
        total1 = total1 - Val(txtDisplay.Text)
        txtDisplay.Clear()
    End Sub
End Class

Please help. Thank you.

[formlesstree4]

Well, you need to draw out your program first on paper. Plan out what the program is actually going to do.
You say you're going to make a calculator, that's fine and dandy. Saying and Doing are two very different things.

Whenever you press a button, you need to have that value be either tacked into a textbox, or into a global variable right, depending on if you did or did not press the +, -, /, or * key.

If you weren't a beginner, I would explain some more processes on how to differentiate on this, but for simplicity's sake, let's do this:

1. Get a piece of paper.
2. Write out what you want the program to ultimately accomplish, the goal of it.
3. Think of the process the program must follow to accomplish this goal.
4. Slowly write out some form of Psuedo-Code
5. Once you have done ALL of the above steps, then you can start using Google (or us) to answer specific questions about your program.
Your question for 'binding' the = key to the - key just doesn't make any sense. The reason you need to do those 5 steps is to build your logical thinking skills. They are so important in programming that all schools require you to take at least Calculus Level Math to develop your logical thinking skills.

Once you've done those steps, come back and ask a few more questions.

[jckryan157]

Well, you need to draw out your program first on paper. Plan out what the program is actually going to do.
You say you're going to make a calculator, that's fine and dandy. Saying and Doing are two very different things.

Whenever you press a button, you need to have that value be either tacked into a textbox, or into a global variable right, depending on if you did or did not press the +, -, /, or * key.

If you weren't a beginner, I would explain some more processes on how to differentiate on this, but for simplicity's sake, let's do this:

1. Get a piece of paper.
2. Write out what you want the program to ultimately accomplish, the goal of it.
3. Think of the process the program must follow to accomplish this goal.
4. Slowly write out some form of Psuedo-Code
5. Once you have done ALL of the above steps, then you can start using Google (or us) to answer specific questions about your program.
Your question for 'binding' the = key to the - key just doesn't make any sense. The reason you need to do those 5 steps is to build your logical thinking skills. They are so important in programming that all schools require you to take at least Calculus Level Math to develop your logical thinking skills.

Once you've done those steps, come back and ask a few more questions.

My logical thinking skills are above average, i am 10th grader, taking calculus AP. Question is:
how can i use "if" (conditional) statement in this code:

Private Sub cmdEquals_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdEquals.Click
        total2 = total1 + Val(txtDisplay.Text)
        txtDisplay.Text = total2
        total1 = 0

? And do i need to add another value like:

Dim total3 As Integer

and use it as a "-" button:

Private Sub cmdMinus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdMinus.Click
        total3 = total3 - Val(txtDisplay.Text)
        txtDisplay.Clear()
    End Sub

?

Thank you for replying.

[formlesstree4]

Very well, I'm an 11th grader taking AP Calculus as well. If your logic skills were more developed you could see that you can use the button clicks to set a global variable. When you press the 'equal' symbol, you can use a Select Case on that Global variable.

Like I said, write this out on the piece of paper so you know what you're doing.

[Megalith]

best way to do globals is in a module, i use something like this

Module modGlobals
    Friend SomeString As String
    Friend AnotherString As String
    Friend SomeDouble As Double
    Friend content As String = Form1.TextBox1.Text
End Module

add this at the very bottom of the code (under End Class). Also note my globals always start with a Caps Letter, helps me to tell a global from a non global instantly.

@formlesstree4 absolutely right, never underestimate the use of pen and paper.

[dbasnett]

You may want to look at this

Parsing Infix Notation