In this project, you are asked to design and implement a class for double link list to hold integers:

- The class should be called DList, you also need a class called Node that contains an int as the data

- Node needs the following data:

int data; //the data held by the node Node* parent; //the parent of the Node Node* child; //the child of the Node

- Node needs the following public functions:
Node(int)// constructor to create a Node with the input int

int GetData(); // return the int held by the Node

- DList needs a head and tail, both should be pointers to Node, and initialized to NULL

- DList needs a default constructor (no parameter), a copy constructor (take const

- DList needs the following public functions:

void PushFront(int a); //create a Node containing a //and add it to the front of the list

void PushEnd(int a); //create a Node containing a //and add it to the end of the list

Node* PopFront(); //popping out the first Node of the list, //if the list is empty, return NULL

void PopEnd(); //popping out the last Node of the list, //if the list is empty, return NULL

DList & as input)

void PrintListForward(); //print every element from start to end //in one line separated by a space

void PrintListReverse(); //print every element from end to start //in one line separated by a space

2 Files to turn in:

You need to turn in four files in a tar.gz file: makefile, main.C, DList.C, DList.h. Among them, you need to use the main.C provided which you cannot modify at all.

DList.h declares the class DList and Node. You can make DList the friend of Node so it can access the private data of the Node.

3 Functions:

All member function and operator prototypes are declared in xArray.h, with necessary comments before each function. The following are major functions:

- PushBack function is the core of this project, and should be used by other functions if necessary (for example, it can be used by the += and >> operators). This function put the integer at the end of the array. Since the array may not have enough space to hold it, you need to grow the array if necessary.

- [ ] operator should check the boundary of data, if idx is not within the boundary, print error message and exit the program; otherwise, return data[idx];

- >> operator should read in an integer and put it at the end of the array.

main.C File

#include "DList.h" #include using namespace std; int main() { DList list; int i; //pust 10 numbers to the end for (i = 0; i < 10; i++) list.PushEnd(i); cout << "Print forward\n"; list.PrintListForward(); cout << "Print reverse\n"; list.PrintListReverse(); cout << "Pop front and print\n"; //print the list from the beginning Node* n = list.PopFront(); while ( n != NULL) { cout << n->GetData() << endl; n = list.PopFront(); } //pust 10 numbers to the front for (i = 0; i < 10; i++) list.PushFront(i); //test copy constructor DList* list2 = new DList(list); cout << "Pop end and print\n"; //print the list from the end n = list2->PopEnd(); while ( n != NULL) { cout << n->GetData() << endl; n = list2->PopEnd(); } return 0; }