Function Checklength(S As String) As Boolean
        Dim c As Integer = 0
        Dim i As Integer = 0
        Dim L As Integer = S.Length
        Dim Yes As String
        Do While i < L
            If S.Substring(i, 1) < Asc("0") Or S.Substring(i, 1) > Asc("9") Then
                Yes = True

            Else
                i += 1

            End If

        Loop

        Return Yes

    End Function

    Private Sub Checkbutt_Click(sender As Object, e As EventArgs) Handles Checkbutt.Click
        Dim S As String

        S = InputTexttxt.Text

        Checklength(S)

        MessageBox.Show(S)

    End Sub
End Class


The Assignment Question-
Write a function that checks whether a string has a number based.  Use what we learned about Asc to complete the following:

Function CheckLength  (S As String) As Boolean
‘add a do loop to start at first character
‘if Ascii current character is between Asc  (“0”) and Asc (“9”)
 ‘then we have a hit  Return True
 ‘else check the next character
 ‘if loop is over, that means no hit was found Return False
End Function

Use this function in an application that allows the user to enter the string/text that should be tested by your CheckLength  function.

The problem i am having. Not usre how i can convert from string to double here.

System.InvalidCastException
  HResult=0x80004002
  Message=Conversion from string "o" to type 'Double' is not valid.
  Source=Microsoft.VisualBasic