exp 3,5,6,7: init

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

2.c

@@ -82,9 +82,10 @@ int main() {
   delete (&head, 2);
   reverse(&head);
 
-  while (head != NULL) {
-    printf("%d ", head->sid);
-    head = head->next;
+  student *cur = head;
+  while (cur != NULL) {
+    printf("%d ", cur->sid);
+    cur = cur->next;
   }
 
   // free