Building Postfix Calculator

xsurvivor1fanx · #1 11-Feb-2008, 16:03

Hi, I'm building a "postfix" calculator for a comp. programming class, and I'm terrible stuck. I have the basic calculator put together, but some of the instructions for the code I am not able to understand. I was wondering if someone could help me. These are the instructions I'm having trouble with:

1. Update txtDisplay to show the current value of the Operand.
2. Modify the event handlers that handle Click events for btnEnter, btnAdd, btnSubtract, btnMultiply, btnDivide so that they update the new TextBox whenever the accumulator is updated.
3. Bring the focus back to txtDisplay using txtDisplay.focus()
4. Select all text in txtDisplay by using txtDisplay.SelectAll()
5. Whenever a button is clicked, the detail of the operation should be recorded in the ListBox. To implement these changes, review how to add a line into a ListBox and how to concatenate strings????

As you can see, I'm terrible confused, so help with any of all of these would be much, much appreciated. Thanks!

xsurvivor1fanx · #2 11-Feb-2008, 18:22

This is the code I have, btw.

VB / Visual Basic Code:

Public Class frmCalc

    Dim accumulator As Double = 0.0
    Dim operand As Double = 0.0

    Private Sub txtDisplay_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtDisplay.Leave
        operand = CDbl(txtDisplay.Text)
    End Sub

    Private Sub btnEnter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEnter.Click
        accumulator = operand
    End Sub

    Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        accumulator += operand
        operand = accumulator
        txtDisplay.Text = operand
    End Sub

    Private Sub btnSubtract_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSubtract.Click
        accumulator -= operand
        operand = accumulator
        txtDisplay.Text = operand
    End Sub

    Private Sub btnMultiply_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMultiply.Click
        accumulator *= operand
        operand = accumulator
        txtDisplay.Text = operand
    End Sub

    Private Sub btnDivide_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDivide.Click
        accumulator /= operand
        operand = accumulator
        txtDisplay.Text = operand
    End Sub

    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        Dim accumulator = 0.0
        Dim operand = 0.0
    End Sub
End Class

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Building Postfix Calculator

Re: Building Postfix Calculator Help