status preordertravers(bitree t,status(* visit)(telemtype e)){
status printelement(telemtype e){
print(e);
return ok;
}
if(t){
if(visit(t->data))
if(preordertraverse(t->lchild.visit))
if(preordertraverse(t->rchild.visit)) return ok;
return error;
}else return ok;
}