Regular Expression to validate 14 digit number using C# and VB.Net in ASP.Net

Last Reply 10 months ago By dharmendr

Posted 10 months ago

I have textbox where user enters date and time.

Reading date and time : 20190704(invalid) ----> Wrong Format

Reading date and time: 20190704000000(valid) ----> Correct Format

(Format-: 20190704000000, Maximum 14 charater without space).

The entered characters length should be 14. If legth is 14 then valid otherwise invalid


Posted 10 months ago

Hi chetan,

Check this example. Now please take its reference and correct your code.


<asp:TextBox runat="server" ID="txtValue" />
<asp:Button Text="Validate" runat="server" OnClick="ValidateText" />


protected void ValidateText(object sender, EventArgs e)
    System.Text.RegularExpressions.Regex regex = new System.Text.RegularExpressions.Regex("^[0-9]{14}$");
    if (regex.IsMatch(txtValue.Text.Trim()))
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Valid')", true);
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Invalid')", true);


Protected Sub ValidateText(ByVal sender As Object, ByVal e As EventArgs)
    Dim regex As System.Text.RegularExpressions.Regex = New System.Text.RegularExpressions.Regex("^[0-9]{14}$")
    If regex.IsMatch(txtValue.Text.Trim()) Then
        ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('Valid')", True)
        ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('Invalid')", True)
    End If
End Sub