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Create a calculator

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Create a calculator

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sam_benne

30 Apr, 2008 - 07:50 AM

Post #1

Here I will shoe you how to create a simple calculator that can add, subtract, divide, multiply and change sign state. Most of the code is commented so it is easy to learn.

For this you will need 19 buttons and one text box (txtNUMBER). Have a look at the picture that is at the bottom on how I have made mine.

first we will declare the variables:

CODE

'Declare the global variables to be used throughout the form
Dim mfirst As Single
Dim msecond As Single
Dim manswer As Single
' Declare the global variables for the operators: Add,Sub,Mul and DIV
Dim mbutton As Integer
'Change the sign of the number from + or - or vice versa
' Depending on its state now they show in txtNUMBER text box
Dim Signstate As Boolean

Second we will make it so that the number buttons actually do something so add the code into the your form:

CODE

Private Sub cmd0_Click()
'Put the value 0 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "0"
End Sub

Private Sub cmd1_Click()
'Put the value 1 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "1"
End Sub

Private Sub cmd2_Click()
'Put the value 2 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "2"
End Sub

Private Sub cmd3_Click()
'Put the value 3 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "3"
End Sub

Private Sub cmd4_Click()
'Put the value 4 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "4"
End Sub

Private Sub cmd5_Click()
'Put the value 5 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "5"
End Sub

Private Sub cmd6_Click()
'Put the value 6 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "6"
End Sub

Private Sub cmd7_Click()
'Put the value 7 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "7"
End Sub

Private Sub cmd8_Click()
'Put the value 8 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "8"
End Sub

Private Sub cmd9_Click()
'Put the value 9 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "9"
End Sub

Noticing that all the number buttons are called cmd# (# is the number) as your buttons need to have these names.

Now we will make the math buttons. The first is the add button:

CODE

Private Sub cmdADD_Click()
'User slected the add button
mbutton = 1
'Convert into a number and transfer the value from
'The text box on the form into the first number
mfirst = Val(txtNUMBER)

txtNUMBER = ""
End Sub

Subtract:

CODE

Private Sub cmdSUBTRACT_Click()
'User slected the minus button
mbutton = 2
'Convert into a number and transfer the value from
'The text box on the form into the first number
mfirst = Val(txtNUMBER)

txtNUMBER = ""
End Sub

Multiply:

CODE

Private Sub cmdMULTIPLY_Click()
'User slected the multiply button
mbutton = 3
'Convert into a number and transfer the value from
'The text box on the form into the first number
mfirst = Val(txtNUMBER)

txtNUMBER = ""
End Sub

Divide:

CODE

Private Sub cmdDIVIDE_Click()
'User slected the Divide button
mbutton = 4
'Convert into a number and transfer the value from
'The text box on the form into the first number
mfirst = Val(txtNUMBER)

txtNUMBER = ""
End Sub

Now we will make the equals button work otherwise theres no point to all this.

CODE

Private Sub cmdEQUALS_Click()
msecond = Val(txtNUMBER)

Select Case mbutton
Case Is = 1
manswer = mfirst + msecond
Case Is = 2
manswer = mfirst - msecond
Case Is = 3
manswer = mfirst * msecond
Case Is = 4
manswer = mfirst / msecond
End Select
txtNUMBER = manswer
End Sub

Now you can test your calculator to see it work. Once you have test we have just a few more bits to add such as the decimal point:

CODE

Private Sub cmdDOT_Click()
txtNUMBER = txtNUMBER + "."
End Sub

The next bit of code is to change the sign state:

CODE

Private Sub cmdSIGN_Click()
'Sign state = false on load of form
If txtNUMBER = "-" + txtNUMBER Then
MsgBox "error start again"
End If
If Signstate = False Then
txtNUMBER = "-" + txtNUMBER
Signstate = True
Else
'SignState = True

minusvalue = Val(txtNUMBER)
'Value now positive
minusvalue = Val("-1" * minusvalue)
txtNUMBER = minusvalue
Signstate = False

End If
End Sub

The next two bits are to cancel meaning empty the textbox and to end the program.

CODE

Private Sub cmdEXIT_Click()
Unload frmCALCULATOR
End Sub

Private Sub cmdCANCEL_Click()
'Remove the values in the txtNUMBER text box
txtNUMBER = " "
End Sub

Now your calculator is complete all you have to do is test it. Since this has a lot of code I have added a text file with the code in it. If you do have any problems then just comment me and I will do what I can to help.

Attached File(s)

code.txt ( 3.27k ) Number of downloads: 389

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Amadeus

7 May, 2008 - 09:37 AM

Post #2

I would suggest it may be prudent to implement some error checking on your divide case - division by zero is never desirable.

sam_benne

7 May, 2008 - 10:24 AM

Post #3

Will update it now so that it does an error check on it.

sam_benne

7 May, 2008 - 10:42 AM

Post #4

Put this:

CODE

    If Val(mfirst) > 0 And Val(msecond) > 0 Then
        manswer = Val(mfirst) / Val(msecond)

    ElseIf Val(Text1.Text) = 0 And Val(msecond) > 0 Then
        manswer = Val(mfirst) / Val(msecond)

    ElseIf Val(Text1.Text) > 0 And Val(msecond) = 0 Then
        manswer = Val(mfirst) / Val(msecond)

    ElseIf Val(Text1.Text) = 0 And Val(msecond) = 0 Then
        manswer = Val(mfirst) / Val(msecond + 1)

    End If

After:

CODE

Select Case mbutton
Case Is = 1
manswer = mfirst + msecond
Case Is = 2
manswer = mfirst - msecond
Case Is = 3
manswer = mfirst * msecond
Case Is = 4
manswer = mfirst / msecond
End Select

As this is an error check for if your dividing 0 by 0.

tthompson1114

22 Jun, 2008 - 05:32 PM

Post #5

When I am writing the code for each button to add the number i press to the text box it gives me an error that says "Operator '+' is not defined for types 'System.Windows.Forms.TextBox' and 'String'. I'm pretty new to Visual Basic 2008 and I have no clue what to do. Any suggestions to this problem?

sam_benne

22 Jun, 2008 - 06:29 PM

Post #6

This is Visual Basic 6 not 2008 sorry

kEsiah

26 Jun, 2008 - 12:26 AM

Post #7

hmm hi der! can i ask u a question? this codes is for standard calculator?

can you help me to my project? my project is to make a standard calculator that has a clear,backspace,and 0.?

sam_benne

26 Jun, 2008 - 06:12 AM

Post #8

It does have a "0" but yes I can help you if you send me what you already have then I will see what I can do.

Reverand Dave
Group Icon

14 Aug, 2008 - 08:46 PM

Post #9

QUOTE(tthompson1114 @ 22 Jun, 2008 - 06:32 PM)

Instead of using the "+" you could use the "&" operator. That way it will include the text in the text box and the int from the button press. so instead of

CODE

Private Sub cmd1_Click()
'Put the value 1 into the txtNUMBER text box
txtNUMBER = txtNUMBER + "1"
End Sub

you would have

CODE

Private Sub cmd1_Click()
'Put the value 1 into the txtNUMBER text box
txtNUMBER = txtNUMBER & "1"
End Sub

This post has been edited by Reverand Dave: 14 Aug, 2008 - 08:48 PM

halogod32

18 Sep, 2008 - 01:46 PM

Post #10

If Any One Is Interested I Remade The Whole Code In VB2008 or VB.NET As Its Become Known. I Will Post It Below. It Works Perfectly And I Used All The Same Names As Sam For The Buttons And Variables, cmd0, cmd1 etc.

CODE

Public Class Form1
    'Declare the global variables to be used throughout the form
    Dim mfirst As Single
    Dim msecond As Single
    Dim manswer As Single
    ' Declare the global variables for the operators: Add,Sub,Mul and DIV
    Dim mbutton As Integer
    'Change the sign of the number from + or - or vice versa
    ' Depending on its state now they show in txtNUMBER text box
    Dim Signstate As Boolean
    Private Sub cmdCLEAR_Click()
        'Remove the values in the txtNUMBER text box
    End Sub
    Private Sub cmdEXIT_Click()
        Me.Close()
    End Sub

    Private Sub cmd0_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd0.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "0"
    End Sub

    Private Sub cmd1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd1.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "1"
    End Sub

    Private Sub cmd2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd2.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "2"
    End Sub

    Private Sub cmd3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd3.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "3"
    End Sub

    Private Sub cmd4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd4.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "4"
    End Sub

    Private Sub cmd5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd5.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "5"
    End Sub

    Private Sub cmd6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd6.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "6"
    End Sub

    Private Sub cmd7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd7.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "7"
    End Sub

    Private Sub cmd8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd8.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "8"
    End Sub

    Private Sub cmd9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd9.Click
        'Put the value 0 into the txtNUMBER text box
        txtNUMBER.Text = txtNUMBER.Text & "9"
    End Sub

    Private Sub cmdSIGN_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSIGN.Click
        Dim MINUSVALUE
        'Sign state = false on load of form
        If txtNUMBER.Text = "-" & txtNUMBER.Text Then
            MsgBox("error start again")
        End If
        If Signstate = False Then
            txtNUMBER.Text = "-" & txtNUMBER.Text
            Signstate = True
        Else
            'SignState = True

            MINUSVALUE = Val(txtNUMBER.Text)
            'Value now positive
            MINUSVALUE = Val("-1" * MINUSVALUE)
            txtNUMBER.Text = MINUSVALUE
            Signstate = False
        End If
    End Sub

    Private Sub cmdSUBTRACT_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSUBTRACT.Click
        'User slected the minus button
        mbutton = 2
        'Convert into a number and transfer the value from
        'The text box on the form into the first number
        mfirst = Val(txtNUMBER.Text)

        txtNUMBER.Text = ""
    End Sub

    Private Sub cmdDOT_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdDOT.Click
        txtNUMBER.Text = txtNUMBER.Text & "."
    End Sub

    Private Sub cmdADD_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdADD.Click
        'User slected the add button
        mbutton = 1
        'Convert into a number and transfer the value from
        'The text box on the form into the first number
        mfirst = Val(txtNUMBER.Text)

        txtNUMBER.Text = ""
    End Sub

    Private Sub cmdDIVIDE_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdDIVIDE.Click
        'User slected the Divide button
        mbutton = 4
        'Convert into a number and transfer the value from
        'The text box on the form into the first number
        mfirst = Val(txtNUMBER.Text)

        txtNUMBER.Text = ""
    End Sub

    Private Sub cmdEQUALS_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdEQUALS.Click
        msecond = Val(txtNUMBER.Text)

        Select Case mbutton
            Case Is = 1
                manswer = mfirst + msecond
            Case Is = 2
                manswer = mfirst - msecond
            Case Is = 3
                manswer = mfirst * msecond
            Case Is = 4
                manswer = mfirst / msecond
        End Select
        txtNUMBER.Text = manswer
    End Sub

    Private Sub cmdMULTIPLY_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdMULTIPLY.Click
        'User slected the multiply button
        mbutton = 3
        'Convert into a number and transfer the value from
        'The text box on the form into the first number
        mfirst = Val(txtNUMBER.Text)

        txtNUMBER.Text = ""
    End Sub

    Private Sub cmdCLEAR_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCLEAR.Click
        mbutton = 0
        txtNUMBER.Text = ""
        manswer = Nothing
    End Sub

    Private Sub cmdCE_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCE.Click
        txtNUMBER.Text = ""
    End Sub
End Class

This post has been edited by halogod32: 18 Sep, 2008 - 01:51 PM

halogod32

18 Sep, 2008 - 01:54 PM

Post #11

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Gmail: {REMOVED}
Yahoo: {REMOVED}
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akhileshbc
Group Icon

27 Sep, 2008 - 09:07 PM

Post #12

Hi, why can't you create a control array for this..???
Create a button and give its name as cmd, then copy it and paste it. It will ask you, whether you want to create a control array. Click Yes. Continue pasting till you reached 10 buttons. Then do the below coding:

CODE

Private Sub cmd_Click(Index As Integer)
txtNUMBER = txtNUMBER & CStr(Index)
End Sub

Instead of the long code:

CODE