Mismatch problem with textbox and label! vb6 - validation

Question

I have tried to change the code but it didnt works.
Here is my code:
Private Sub CTcash_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
bill = Val(CTcash.Text - CLtotaloutput.Caption)
If Val(bill) > 0 Then
Change.CLchange.Caption = Val(bill)
Change.CLchange.Caption = Format(bill, "Rp\. ###,###,###.-")
Change.Show
End If
If Val(bill) < 0 Then
MsgBox "Not Enough Money", vbOKOnly, "Invalid"
End If
End If
End Sub
The highlighted code
bill = Val(CTcash.Text - CLtotaloutput.Caption)

Answer 1

Both CTcash.Text and CLTotaloutput.Caption are text strings so you can't subtract them directly. Try:
bill = Val(CTcash.text) - Val(CLtotaloutput.Caption)
You really should ensure that both strings are numerical first though!

Answer 2

#John Eason is correct. You also do not have to use Val on bill since it is already an integer. And you are not doing anything if bill is 0 but this could be fine based on your requirements.
Private Sub CTcash_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
bill = Val(CTcash.Text) - Val(CLtotaloutput.Caption)
If bill > 0 Then ' Note that when bill is 0 nothing happens but that might be fine
'Change.CLchange.Caption = bill 'Not sure why this is needed but it may be
Change.CLchange.Caption = Format(bill, "Rp\. ###,###,###.-")
Change.Show
End If
If bill < 0 Then
MsgBox "Not Enough Money", vbOKOnly, "Invalid"
End If
End If
End Sub
I think a better approach would be to use a Select Case statement.
Private Sub CTcash_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
bill = Val(CTcash.Text) - Val(CLtotaloutput.Caption)
Select Case True
Case bill > 0
Change.CLchange.Caption = Format(bill, "Rp\. ###,###,###.-")
Change.Show
Case bill < 0
MsgBox "Not Enough Money", vbOKOnly, "Invalid"
Case Else
' Do nothing - this documents that this is done on purpose
End Select
End If
End Sub
You can use IsNumeric function to check if the inputs are numeric and parse accordingly. Use the Right function to remove any non-numbers from the left side. For example, Right("$123", Len("$123") - 1) will remove the leading $.
To strip all non-numerical values from a string:
Dim ResultString As String
myString = "aaa34BB12,000xcv9.9zz"
Dim i As Integer
For i = 1 To Len(myString)
myChar = Mid(myString, i, 1)
If IsNumeric(myChar) = True Then
ResultString = ResultString + myChar
End If
Next
MsgBox ResultString
Note that this may cause an issue with decimal amounts since 1.23 will before 123. Not something you want. Try using the CCur function. I have never used it myself but it might be exactly what you want.
Source: https://www.vbforums.com/showthread.php?437526-RESOLVED-Removing-non-numeric-chars-from-a-string&p=2686411&viewfull=1#post2686411

Answer 3

At first I miss the const, i put it in the other sub:
Private Sub CTcash_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
bill = Val(CTcash.Text) - totalsum
Select Case True
Case bill > 0
Change.CLchange.Caption = Format(bill, "Rp\. ###,###,###.-")
Change.Show
Case bill < 0
MsgBox "Not Enough Money", vbOKOnly, "Invalid"
Case Else
End Select
End If
End Sub
Private Sub CTbarcode_KeyUp(KeyCode As Integer, Shift As Integer)
Select Case KeyCode
Case Is = vbKeyF6
totaldiscount = 200
totalsum = Val(CLsuboutput.Caption) - totaldiscount
CLtotaloutput.Caption = Format(totalsum, "Rp\. ###,###,###. ,-")
CLdiscoutput.Caption = Format(totaldiscount, "Rp\. ###,###,###. ,-")
CTcash.Enabled = True
CTcash.SetFocus
End Select
End Sub
Here is it after i edit it:
Private Sub CTcash_KeyPress(KeyAscii As Integer)
If KeyAscii = 13 Then
totaldiscount = 200
totalsum = Val(CLsuboutput.Caption) - totaldiscount
bill = Val(CTcash.Text) - totalsum
Select Case True
Case bill > 0
Change.CLchange.Caption = Format(bill, "Rp\. ###,###,###.-")
Change.Show
Case bill < 0
MsgBox "Not Enough Money", vbOKOnly, "Invalid"
Case Else
End Select
End If
End Sub