Validating a text box

hi! i want to make validation on a text box so that the first character is only A, B, C, or X..

Code:

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sCustomerAccountNumber = txtCustomerAccountNumber.text

If sCustomerAccountNumber.Chars(0) <> Chr(65) Then
            sErrorMessage = sErrorMessage & "Customer Account Number should start with a letter!" & vbCrLf & "e.g. A, B, C or X" & vbCrLf & "e.g. A1234567" & vbCrLf
            bErrorOccurred = True
        ElseIf sCustomerAccountNumber.Chars(0) <> Chr(66) Then
            sErrorMessage = sErrorMessage & "Customer Account Number should start with a letter!" & vbCrLf & "e.g. A, B, C or X" & vbCrLf & "e.g. A1234567" & vbCrLf
            bErrorOccurred = True
        ElseIf sCustomerAccountNumber.Chars(0) <> Chr(67) Then
            sErrorMessage = sErrorMessage & "Customer Account Number should start with a letter!" & vbCrLf & "e.g. A, B, C or X" & vbCrLf & "e.g. A1234567" & vbCrLf
            bErrorOccurred = True
        ElseIf sCustomerAccountNumber.Chars(0) <> Chr(88) Then
            sErrorMessage = sErrorMessage & "Customer Account Number should start with a letter!" & vbCrLf & "e.g. A, B, C or X" & vbCrLf & "e.g. A1234567" & vbCrLf
            bErrorOccurred = True
End If

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what happens with these code is whenever i try to put in A, B, C, or X.. i get the error message.. should i convert this into a loop..??

can someone close this..?? already found out how to do it..

Click on Thread Tools, and then Mark as RESOLVED. Only you can close it out.

Also, it'd help the next person to post the answer to any question.

Thanks

You should also look at Regular Expressions. You will have to write less code and it will be easier to maintain and understand.

what's Regular Expressions..??

this is what i did:

Code:

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sChar1 = Mid(txtCustomerAccountNumber.text, 1, 1)

If sChar1 <> "A" And sChar1 <> "B" And sChar1 <> "C" And sChar1 <> "X" Then
            sErrorMessage = sErrorMessage & "Customer Acount Number should start with A, B, C, or X" & vbCrLf & "e.g. A, B, C or X" & vbCrLf & "e.g. A1234567" & vbCrLf
            bErrorOccurred = True

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but it didn't work properly... any suggestions..??

Use a regular expression such as Shuja Ali suggests to make the validation logic.

You can take a look at it here:
http://msdn.microsoft.com/en-us/library/hs600312.aspx

It is a powerful tool and well worth the time to get introduced to.

Normally I just use an instr statement for such checks.

Code:

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Dim ValidChars as String="ABCX"
 
if instr(ValidChars,Mid(txtCustomerAccountNumber.text, 1, 1))=0 then
 
' do error stuff here
end if

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Quote:

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Originally Posted by manil

hi! i want to make validation on a text box so that the first character is only A, B, C, or X..
...

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Code:

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                Select Case sCustomerAccountNumber.Chars(0)
                        Case "A", "B", "C", "X"
                                'Is ok
                        Case Else
                                'Is Wrong
                                sErrorMessage &= "Customer Account Number should start with a letter!" & vbCrLf & _
                                                                "e.g. A, B, C or X" & vbCrLf & _
                                                                "e.g. A1234567" & vbCrLf
                                bErrorOccurred = True
                End Select

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How about a custom user control that takes a regular expression as a property and an isvalid property that gets set when valid - you could include an error provider in the control.