Linked List Using Class In C++

[Barton Ostby]

Thelinked list stores data in sequential storage, like arrays. Though the data are stored sequentially, the memory locations are not contiguous.

Unlike an array, the linked list can store data of different data types.

The below diagram represents the linked-list structure.

All of the operations perform as could be expected for a doubly-linked list. Operations that index into the list will traverse the list from the beginning or the end, whichever is closer to the specified index. Note that this implementation is not synchronized. If multiple threads access a linked list concurrently, and at least one of the threads modifies the list structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements; merely setting the value of an element is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the list. If no such object exists, the list should be "wrapped" using the Collections.synchronizedList method. This is best done at creation time, to prevent accidental unsynchronized access to the list: List list = Collections.synchronizedList(new LinkedList(...)); The iterators returned by this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the Iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future. Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs. This class is a member of the Java Collections Framework.Since:1.2See Also:List, ArrayList, Serialized FormField SummaryFields inherited from class java.util.AbstractListmodCountConstructor SummaryConstructors Constructor and DescriptionLinkedList()Constructs an empty list.LinkedList(Collection

the only one difference is a field in both them. In MyStruct field a is public and in MyClass field a is private. Of course you can manipulate them using public and private keywords in structs and classes both.

A linked list is one thing, its nodes are another thing. The nodes are part of the implementation of the list. They should not be visible in the interface of a list so their form doesn't really matter. I would do this

A linked list is a linear data structure that consists of a sequence of nodes, where each node stores a piece of data and a reference (pointer) to the next node in the List. Linked lists are useful for storing data collections when the collection size is not known in advance or when the data is frequently inserted or deleted.

In C++, we can create a linked list by defining a node class and a linked list class. The node class will represent a single node in the List and contain a data field and a pointer to the next node. The linked list class will contain a head pointer to the first node in the List and various methods for inserting, deleting, and traversing the nodes in the List.

This node class has a public data field data of type int and a public pointer next to the next node in the List. It also has a constructor that initializes the data field and sets the next pointer to nullptr.

This linked list class has a private field head that points to the first node in the List and various public methods for inserting and deleting nodes at the beginning and end of the List and for printing the List to the console. This program will create a linked list, insert some nodes at the beginning and end of the List, delete a node at the beginning and end of the List, and print the List to the console.

In the above code, we have defined a template class Node that represents a single node in a linked list. The Node class has a public data field data of type T (where T is a template parameter) and a public pointer next to the next node in the List. It also has a constructor that initializes the data field and sets the next pointer to nullptr.

We have also defined a template class, LinkedList, that represents a linked list and contains a private field head that points to the first node in the List. The LinkedList class has various public methods for inserting and deleting nodes at the beginning and end of the List and for printing the List to the console.

The insertAtBeginning method creates a new node with the given data and inserts it at the beginning of the List by updating the head pointer. The insertAtEnd method creates a new node with the given data and inserts it at the end of the List by traversing it and updating the last node's next pointer. The deleteAtBeginning method deletes the first node in the List by updating the head pointer and freeing up the memory used by the node. The deleteAtEnd method deletes the last node in the List by traversing the List and updating the next pointer of the second to the last node. The printList method traverses the List and prints the data of each node to the console.

In the main function, we create an instance of the LinkedList class and call the various methods to insert and delete nodes and print the List. The output shows the original List, the List after deleting a node at the beginning, and the List after deleting a node at the end.

This is the most simple example I can think of in this case and is not tested. Please consider that this uses some bad practices and does not go the way you normally would go with C++ (initialize lists, separation of declaration and definition, and so on). But that are topics I can't cover here.

EDIT: added a pop function and some output. As you can see the program pushes 3 values 5, 10, 20 and afterwards pops them. The order is reversed afterwards because this list works in stack mode (LIFO, Last in First out)

I also took the opportunity to make a suggested edit; instead of having two funcitons to malloc, I put it in initNode() and then used initNode() to malloc both (malloc is "the C new" if you will). I changed initNode() to return a pointer.

Both functions are wrong. First of all function initNode has a confusing name. It should be named as for example initList and should not do the task of addNode. That is, it should not add a value to the list.

I've been writing my linked list data structure from scratch as a student for projects/assignments and I was wondering in the "real-world" does a developer have to write their own linked list DS or use any of the already provided linked list object in the Java docs. Which is better & in what scenario?

A custom LinkedList implementation will very likely be more efficient because it allows you to make optimizations for your needs, however the JDK's LinkedList will always be preferable for its re-usability and maintainability benefits:

Thus, the "technical" answer is: for production work you have to assess cost/benefit of both of those alternatives; and then you decide what to do. But especially for classes that come out of the Java standard libraries, you should prefer re-use. You depend on those libraries anyway; so there is no point in not using them.

B) cost of doing so: of course, the direct cost for creating and maintaining your own solution over time (esp. maintenance is often heavily underestimated! And of course, all those points that "castle" listed in his answer.

I have a class of events.Now All I have to do is to create events and store them in a linked list. but I don't know how to fix the head position. I mean if i define head to be NULL in a constructor then for every new event it would re-defined to be NULL. Thus I will have only one event in my linked list.My code is something like this:

First off, the code shows that class Event is self-contained. Which is to say that head and nxt are part of the object itself. If you wish to use a Linked List of objects linking to each other but not maintaining the head outside then I would do the following...

Now, your event class will in fact need some helper methods such as next and previous pointers. You can implement them directly or create a third class that is either inherited from or have it contain the event class.

By contrast, in the version with distinct LinkedList and Node types, there is a clear distinction between the roles. And if you then make the Node class a private inner class of LinkedList, then the latter can manage the data structure to prevent undesirable structures (e.g. cycles) from being formed.

Indeed. Judicious use of abstraction reduces the confusion. By hiding the list data structures and the methods that manipulate them behind the abstraction boundary of your LinkedList class, you make it easier to write code that can safely use the lists.

The one-class method looks rather limiting, does it not? The benefits of using a Linked List is for an easy way to access the head and tail of it. Having a Linked List improves runtime significantly, rather than going through each Node to find the tail. When it comes to deletion, which is definitely a crucial topic in a data structures course, the two-class method is much much more practical than the one-class method. In the two-class method, you can iterate through and reassign heads or tails as you please. In the one-class method, whichever node you create first means everything, and because you can't have a defined head or tail, keeping track of all the Nodes after deletions occur becomes significantly challenging. TLDR: two-class method allows for much easier access and in turn, faster runtimes.

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