CODEWITHSUNDEEP
regexvb.net
eidsonator
eidsonator

Reputation: 1325

Visual Basic RegularExpression Digits only

I should preface this by stating that Visual Basic is not my native language, but I am maintaining a legacy program until which time it can be ported to a different language.

We have a Textbox that is used to enter a quantity. This quantity should be whole numbers only, and this was not being validated. A decimal sneaked into the database and I've been asked to add validation of input. I have tried a Regular Expression. 

Function validate_qty(qty As String)
    Dim objRegExp As New System.Text.RegularExpressions.Regex("^\d+$")
    Dim match As System.Text.RegularExpressions.Match = objRegExp.Match(qty)
    If match.Success Then
        Return True
    End If
    Return False
End Function

This is working as far as decimal points is concerned: .1 and 1.0 return false; however, alphanumeric strings such as a1212 or 433498e return True

Any insight? It would be greatly appreciated.

Upvotes: 0

Views: 14053

Answers (4)

Monwabisi
Monwabisi

Reputation: 3

I also do not see where your error might be on your regex

but try.

btnSave/formload()
dim num as new regex("^\d+$")

if num.Ismatch(yourtextbox1.text) then    
    yourtextbox1.text="num" 

else 
    yourtextbox.text="invalid num"
    exit sub

end if

after this you accept if its correct or terminate by "exit sub " if its incorrect.

Upvotes: 0

freefaller
freefaller

Reputation: 19953

Other than shortening the function, I can't see a problem with your RegEx...

Private Function validate_qty(Byval qty As String) As Boolean
   Dim objRegExp As New System.Text.RegularExpressions.Regex("^\d+$")
   Return objRegExp.Match(qty).Success
End Function

Another option would be to use the static Integer.TryParse...

Private Function validate_qty(Byval qty As String) As Boolean
   Return Integer.TryParse(qty, Nothing)
End Function

Upvotes: 2

keyboardP
keyboardP

Reputation: 69372

You could create a function which returns a "cleaned" string (i.e. one that has any non-digits removed)

Public Function KeepNumbers(input As String) As String
    Dim sb As New StringBuilder()
    For Each c As Char In input
        If [Char].IsDigit(c) Then
            sb.Append(c)
        End If
    Next
    Return sb.ToString()
End Function

Upvotes: 0

matzone
matzone

Reputation: 5719

I dont think you need regex yet ..

Function validate_qty(qty As String) As Boolean
    if qty.Contains(".") then Return False
    Return IsNumeric(qty)
End Function

Upvotes: 1

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