How to upload text and excel files in dot net

[divyagiridhar]

How do i specify the file type as text and excel when i want to upload a file using dotnet

My code is as follows:

<script language="C#" runat="Server">
//Event Handler for the upload button
void UploadFile(object Sender,EventArgs E)
{
if (File1.PostedFile !=null) //Checking for valid file
{
// Since the PostedFile.FileNameFileName gives the entire path we use Substring function to rip of the filename alone.
string StrFileName = File1.PostedFile.FileName.Substring(File1.PostedFi le.FileName.LastIndexOf("\\") + 1) ;
string StrFileType = File1.PostedFile.ContentType;

// string StrFileType = File1.PostedFile.ContentType("video/mpeg") ;

int IntFileSize =File1.PostedFile.ContentLength;
//Checking for the length of the file. If length is 0 then file is not uploaded.
if (IntFileSize <=0)
Response.Write(" <font color='Red' size='4'>Uploading of file " + StrFileName + " failed </font>");
else
{
if (File1.PostedFile.ContentType == "text/txt")
{
File1.PostedFile.SaveAs(Server.MapPath(".\\" + StrFileName));
}
Response.Write( "<font color='blue' size='4'>Your file " + StrFileName + " of type " + StrFileType + " and size " + IntFileSize.ToString() + " bytes was uploaded successfully</font>");
}
}
}
</script>