Create a calculator Options

[sam_benne]

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.