Hi i hold a Pakistani passport
and i have a b permit here.

will be travelling to north america soon and have applied for the visa

but can i exit switzerland and enter back without a hassle.

or do i just need to present my passport and my b permit in northamerica
for my return flight and back at immigration here in switzerland

or do i need a re entry visa as well(if so from where?)

and if so,where does that get stamped?
on the passport?for what i have heard,they said that the b permit is the id and thats all that is needed?

any help and info would be appreciated.
thanx

Your B permit plus passport is adequate for re-entry. Just don't forget them!

The airline will quite likely want them for check-in (they get a big fine for allowing people without appropriate visas to board the plane!)...

And you'll need them to get through passport control when you arrive in Europe.