For each loop to reverse a string (VB.net) : For Each « Language Basics « ASP.Net






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For each loop to reverse a string (VB.net)

<%@ Page Language="VB" %>
<script runat="server">
    Function ValidateCard(cardNumber As String) As Boolean
      Dim reverseNumber As String
      Dim ch As Char
    
      For Each ch in cardNumber
        reverseNumber = ch & reverseNumber
      Next
    
      Dim doubledAlternates As String
      Dim thisDigit, index As Integer
    
      For index = 1 to reverseNumber.Length
        thisDigit = CInt(reverseNumber.SubString(index - 1, 1))
        If index mod 2 = 0 Then
          thisDigit = thisDigit * 2
        End If
        doubledAlternates = doubledAlternates & thisDigit
      Next
    
      Dim sum As Integer
      For index = 1 to doubledAlternates.Length
        sum = sum + CInt(doubledAlternates.SubString(index - 1, 1))
      Next
    
      ValidateCard = sum <> 0 AND sum mod 10 = 0
    
    End Function
    
    Sub Button1_Click(sender As Object, e As EventArgs)
      If ValidateCard(TextBox1.Text) Then
        Label1.Text = "That'll do nicely sir!"
      Else
        Label1.Text = "There's nothing for you here!"
      End If
    End Sub

</script>
<html>
<head>
</head>
<body>
    <form runat="server">
        <p>
            Enter the number: 
            <asp:TextBox id="TextBox1" runat="server"></asp:TextBox>
        </p>
        <p>
            <asp:Button id="Button1" onclick="Button1_Click" runat="server" Text="Check Card Number"></asp:Button>
        </p>
        <p>
            <asp:Label id="Label1" runat="server"></asp:Label>
        </p>
    </form>
</body>
</html>








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