how to upload only particular formate file in asp.net

if you want to validate from the client side use the following:

function ValidatePDFupload(Source, flag)
{
var pathTextBox = document.getElementById('txtBoxFilePath');
var FileUploadPath = pathTextBox.value;


var FileExtension = FileUploadPath.substring(FileUploadPath.lastIndexOf('.') + 1).toLowerCase();


if (FileExtension == "pdf")
{
flag.IsValid = true;  // Allow to upload PDF File
}
else
{
flag.IsValid = false; // Don't allow to upload pdf file
}


}

if you want to validate from the server side, use the following:

string p = @"C:\Users\linton\Documents\Sample.pdf";

        string e = Path.GetExtension(p);
        if (e == ".pdf")
        {
            Console.WriteLine(e);
        }