Thread: correct order to insert new node?

In theory, yes, that's fine. In practice, you'll need to do a bit more checking (this is overly cautious, assuming Cur may be null):

Code:

P->Next = Cur;
if (Cur) {
  P->Before = Cur->Before;
}
else {
  P->Before = 0;
}
if (P->Before) {
  P->Before->Next = P;
}
if (P->Next) {
  P->Next->Before = P;
}