VB.NET: IsNumeric using RegEX

[Shuja Ali]

To check if a string is a valid number we either have to use the Try..Catch..Finally with Integer.Parse or try Double.TryParse.

I just saw a method using regular expressions sometime back

Public Function IsNumeric(ByVal inputString As String) As Boolean
        Dim _isNumber As System.Text.RegularExpressions.Regex = New _
System.Text.RegularExpressions.Regex("(^[-+]?\d+(,?\d*)*\.?\d*([Ee][-+]\d*)?$)|(^[-+]?\d?(,?\d*)*\.\d+([Ee][-+]\d*)?$)")
        Return _isNumber.Match(inputString).Success
    End Function

We can call this function like this

If isNumeric("1234") Then
   MessageBox.Show("String is Numeric")
Else
   MessageBox.Show("String is not Numeric")
End If

Edit--
I have got this RegEx from Internet which checks almost all the possibilities.

[|2eM!x]

Thought I might post this bit of code in the same type thread

Private Function IsNumeric(ByVal Str As String) As Boolean
        Const Upper As Int32 = 57
        Const Lower As Int32 = 48
        For Each a As Char In Str
            Dim Base As Int16 = Convert.ToInt16(a)
            If (Base <= Upper And Base >= Lower) = False Then
                Return False
            End If
        Next
        Return True
    End Function