Download File, Not open it

I have this link

<a href=http://site/file.txt>Download</a>

how can I download file.txt or file.doc using php when I click link or click button (<input type=buttom>) .. I mean do not open file with bowser .. ?

such as using (Save target as) but by click on button or link ?

just as you got. you can't control the browser if it gives you that message. that is a security message and there for a reason.