Classes with Dynamic Data Structures X

TestFriends.C

ListOfFriends list1;

This declaration implicitly calls the constructor of ListOfFriends that takes no parameters. root will be simply set to 0 in this case (empty list).

TestFriends.C

ListOfFriends list2(list1);

This declaration is equivalent to
ListOfFriends list2 = list1
and causes the copy constructor of ListOfFriends to be invoked which recursively duplicates the binary tree of list1 for list2.

TestFriends.C

ListOfFriends list3; list3 = list1;

Firstly, list3 is created using the constructor of ListOfFriends without parameters. Secondly, the assignment operator of ListOfFriends performs the work for list3 = list1.