DD is 3 1/2. She finds it funny to bite (hard enough to bruise/ leave teethmarks), pinch, poke, scratch, pull hair. We are struggling to get her to stop. I've told her it hurts, ignored her, put her straight down and walked off, shouted... all that happens now is she laughs and spits in our face 
She is our fifth but our others are adults. When they were little we smacked, and both DH and I were smacked as children. We don't know any other way of disciplining but realise that now most parents don't smack, so had made a conscious decision not to.
It has backfired on us because she is turning into a little brat :( I really don't remember the others being this violent (though I expect they were to each other). I did smack her for the first time last week when she hit me round the face with a packet of biscuits and the shock of it stopped her completely.
So far it's only me & DH that get attacked and there are no young siblings to worry about, but she goes to school next year and this behaviour is totally unacceptable.
Any tips please?