Designing a C + + Universal Linked list: implementing polymorphic bidirectional functions

Before using C to implement the universal linked list, the data domain of the linked list from the specific type to the void* pointer, the use of C to achieve the strength is the pointer assignment and also to achieve universal printing

Link: c Implementation of the common bidirectional chain performance in C + + re-implementation, the idea is mostly consistent:

Instead of using the template class, the virtual function is used to achieve polymorphism, and the data field does not store any information about the type, but the pointer, which puts it in an abstract class, and is connected by the pointer.

The list has a pointer to the end of the head and a series of insert delete print operations, all written in the linked list class.

The list pointer type is a linked list node class, the node's pointer field and data field are pointer types, and the data field points to an abstract class object object.

The object class is an abstract class that, when it is necessary to store integer data in a linked list, implements a subclass of the integer to inherit the class, must implement the virtual function in the abstract class, take the printing function as an example, each subclass of a different data type must have its own printing function, and object does not care how to print.

Class Intobject:p ublic object{public:intobject (int d = 0):d ata (d) {}~intobject () {}void Print () const{cout << Data & lt;< "--";} Private:int data;};/ Class Strobject:p ublic object{public:strobject (char * STR) {if (str = = NULL) {data = new char[1];d ata[0] = ' + ';} Else{data = new Char[strlen (str) + 1];strcpy (data, str);}} ~strobject () {}void Print () const{cout << "\" "<< data <<" \ "" << "--";} Private:char * data;};/ Class Floatobject:p ublic object{public:floatobject ( Float d = 0):d ata (d) {}~floatobject () {}void Print () const{cout << data << "-";} Private:float data;};/ void Main () {list mylist;for (int i = 0; i < 5; ++i) { Intobject *pi = new Intobject (i); Mylist.push_back (pi);} Mylist.printlist (); char* arr[5] = {"Affd", "FDAs", "FDFSS", "ere", "Qret"};for (int i = 0; i < 5; i++) {strobject*ps = new Strobject (Arr[i]); Mylist.push_back (PS);} Mylist.printlist (); float brr[5] = {0.34, 54.32, 0.53, 43.2, 5.878};for (int i = 0; i < 5; i++) {floatobject*ps = new F Loatobject (Brr[i]); Mylist.push_back (PS);} Mylist.printlist ();}

Release of the linked list:

Class Object{public:object () {}virtual ~object ()//Because it is a virtual function, the destructor of the parent class is mobilized while the deconstruction of the child class is transferred {}////defines the interface universal print virtual void print () const = 0 };class List;class Listnode{friend class List;public:listnode () {data = Null;next = NULL After inheriting the pure virtual function subclass must be implemented) ListNode (Object *pobj) {data = Pobj;next = NULL;} ~listnode () {Delete data;next = NULL;} Private:object *data;listnode *next;}; Class List{public:list () {head = tail = new ListNode;} ~list () {ListNode *delp = head->next;while (delp!= tail) {Head->next = Delp->next;delete Delp;delp = head-> Next;} Delete Head;head = tail = NULL;} void Push_back (Object *pb)//tail interpolation {ListNode *s = new ListNode (PB); assert (s! = NULL); tail->next = S;tail = s;} void Printlist () const{listnode *p = Head->next;while (P! = NULL) {p->data->print ();p = P->next;} cout << "NULL" << Endl;} Private:listnode *head;listnode *tail;};/ Class Intobject:p ublic object{public:intobject (int d = 0 ):d ATA (d) {}~intobject () {CoUT << "Delete int" << Endl;} void Print () const{cout << data << "--";} Private:int data;};/ Class Strobject:p ublic object{public:strobject (char * STR) {if (str = = NULL) {data = new char[1];d ata[0] = ' + ';} Else{data = new Char[strlen (str) + 1];strcpy (data, str);}} ~strobject () {cout << "delete string" << endl;delete []data;data = NULL;} void Print () const{cout << "\" "<< data <<" \ "" << "--";} Private:char * data;};