CSC195, Class 43: Queues

Overview:
* Short note on ** notation.
* Lab.

Notes:
* Gries for Friday or Monday.
* Sam gone for the weekend.  Class Monday no longer a surprise.
* Cool talk today at 4:15.
* Showings of "Sorting Out Sorting" Monday at 10:00 a.m. and 2:15
  p.m.

Observation: We occasionally have pointers to things and we
want to change what they point to within a procedure.

typedef struct node {
  void *contents;
  node *next;
} node;

Non-working code

advance(node *cursor) {
  cursor = cursor->next;
}
fred = ...;
advance(fred);

To change something, you pass its address ...

New code
advance(node **cursor) {
  *cursor = (*cursor)->next;
}
advance(&fred);