Cookie Helper default expire time

[eluser]bbiao[/eluser]
[quote author="inparo" date="1210043567"]I think you're missing what the default is for. It's only used to delete the cookie.

By telling the browser that the cookie has expired, it will be trashed on the next request.[/quote]

i don't think so.
the ci docs said that:
Only the name and value are required.
so if i just pass the name and value, the cookie will be deleted, isn't it?

for example:
set_cookie('name', $value);

what happened after i call this?? the cookie will be deleted!! this is not what i want