Let us start with a sample demo. Open Visual Studio. Create one empty web application. Add a web form. Write the following HTML mark up in the page.
- <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Index.aspx.cs" Inherits="GetFileExtension.Index" %>
- <!DOCTYPE html>
- <html xmlns="http://www.w3.org/1999/xhtml">
-
- <head runat="server">
- <title></title>
- </head>
-
- <body>
- <form id="form1" runat="server">
- <div>
- <asp:FileUpload ID="FileUp" runat="server" /><br /><br />
- <asp:Button ID="BtnGetExtension" runat="server" Text="Get Extension" /><br />
- <asp:Label ID="LblExtension" runat="server" style="color:red"></asp:Label>
- </div>
- </form>
- </body>
-
- </html>
- using System;
- usingSystem.Collections.Generic;
- usingSystem.Linq;
- usingSystem.Web;
- usingSystem.Web.UI;
- usingSystem.Web.UI.WebControls;
- namespaceGetFileExtension
- {
- public partial class Index: System.Web.UI.Page
- {
- protected void Page_Load(object sender, EventArgs e)
- {
- }
- protected void BtnGetExtension_Click(object sender, EventArgs e)
- {
- if (FileUp.HasFile)
- {
- stringInputFile = string.Empty;
- InputFile = System.IO.Path.GetExtension(FileUp.FileName);
- LblExtension.Text = "The extension of the file is: " + InputFile;
- }
- else
- {
- LblExtension.Text = "Please upload a file!!";
- }
- }
- }
- }
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We got the correct extension of the file uploaded previously. In case the user directly clicks the button without uploading the file then the below error should appear.
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