Force browser to download PDF document instead of opening it

Question

I want to make the browser download a PDF document from server instead of opening the file in browser itself. I am using C#.

Below is my sample code which I used. It

Answer 1

They are almost same in most of the cases but there is a difference:

Add Header will replace the previous entry with the same key

Append header will not replace the key, rather will add another one.