Printing output with format (page x)-> in cpp - c++

Question

Please provide the implementation of functions append, printList, and delete_evens as described in the comments. You will be dealing with a linked list of pages in which every node (page), is linked to its next and previous node (page) using next and prev pointers respectively. Please note the previous node of the first node (head) is NULL. In a similar way, the next of the last node will also be NULL.
The expected output is as follows:
Created PageList:
(page1)->(page2)->(page3)->(page4)->(page5)->(page6)->(page7)->(page8)->(page9)->(page10)->(page11)->(page12)->(page13)->(page14)->(page15)->(page16)->(page17)->(page18)->(page19)->(page20)->(page21)->(page22)->(page23)->(page24)->(page25)->(page26)->(page27)->(page28)->(page29)->(page30)->(page31)->(page32)->(page33)->(page34)->(page35)->(page36)->(page37)->(page38)->(page39)->(page40)->(page41)->(page42)->(page43)->(page44)->(page45)->(page46)->(page47)->(page48)->(page49)->(page50)->
Updated PageList:
(page1)->(page3)->(page5)->(page7)->(page9)->(page11)->(page13)->(page15)->(page17)->(page19)->(page21)->(page23)->(page25)->(page27)->(page29)->(page31)->(page33)->(page35)->(page37)->(page39)->(page41)->(page43)->(page45)->(page47)->(page49)->
The output I am getting is:
Created PageList:
(page)->1 (page)->2 (page)->3 (page)->4 (page)->5 (page)->6 (page)->7 (page)->8 (page)->9 (page)->10 (page)->11 (page)->12 (page)->13 (page)->14 (page)->15 (page)->16 (page)->17 (page)->18 (page)->19 (page)->20 (page)->21 (page)->22 (page)->23 (page)->24 (page)->25 (page)->26 (page)->27 (page)->28 (page)->29 (page)->30 (page)->31 (page)->32 (page)->33 (page)->34 (page)->35 (page)->36 (page)->37 (page)->38 (page)->39 (page)->40 (page)->41 (page)->42 (page)->43 (page)->44 (page)->45 (page)->46 (page)->47 (page)->48 (page)->49 (page)->50
Updated PageList:
(page)->1 (page)->3 (page)->5 (page)->7 (page)->9 (page)->11 (page)->13 (page)->15 (page)->17 (page)->19 (page)->21 (page)->23 (page)->25 (page)->27 (page)->29 (page)->31 (page)->33 (page)->35 (page)->37 (page)->39 (page)->41 (page)->43 (page)->45 (page)->47 (page)->49
My code is as follows:
#include <iostream>
#include <string>
using namespace std;
class Page {
public:
int page_number = 0;
string page_content = "";
Page *next = NULL;
Page *prev = NULL; // previous
};
class PageList {
public:
Page *head = NULL; // point to the first page
// append a page to the end of the list
void append(int page_number, string page_content) {
Page *first;
first = new Page();
first->page_content = page_content;
first->next = NULL;
first->prev = NULL;
first->page_number = page_number;
if (head == NULL) {
head = first;
} else {
Page *second = head;
while (second->next != NULL) {
second = second->next;
}
second->next = first;
}
}
// print all the elements of the list (pages) with the given format
void print list(Page *node, bool forward) {
while (node != NULL) {
cout << node->page_content << " ";
node = node->next;
}
cout << endl;
}
void delete_evens() { // delete the pages with even page_number
Page *first = head;
Page *q = NULL;
while (first != NULL) {
if (first->page_number % 2 == 0) {
if (q == NULL) {
head = first->next;
first = first->next;
} else {
q->next = first->next;
first->next = NULL;
first = q->next;
}
} else {
if (q == NULL) {
q = first;
first = first->next;
} else {
q = q->next;
first = first->next;
}
}
}
}
PageList(int pages) noexcept // consteructor
{
head = NULL;
for (int i = 1; i <= pages; i++) {
append(i, "(page" + to_string(i));
}
cout << "Created PageList:" << endl;
printList(head, true);
delete_evens();
cout << "Updated PageList:" << endl;
printList(head, true);
}
};
int main() {
PageList list(50);
return 0;
}
I believe that the error is somewhere in the line append(i, "(page" + to_string(i));
Can someone please help?

Answer 1

#include <iostream>
#include <string>
using namespace std;
// -------------------------------------------------------------------
class Page {
public:
int page_number = 0;
string page_content = "";
Page* next = NULL;
Page* prev = NULL;// previous
};
class PageList {
public:
Page* head=NULL; // point to the first page
// append a page to the end of the list
void append(int page_number, string page_content){
Page* first;
first=new Page();
first->page_content = page_content;
first->next=NULL;
first->prev=NULL;
first->page_number=page_number;
if(head==NULL) {
head=first;
}
else{
Page* second=head;
while(second->next != NULL) {
second=second->next;
}
second->next=first;
}
}
// print all the elements of the list (pages) with the given format
void printList(Page* node, bool forward) {
while(node != NULL) {
cout<<node->page_content<<""<<")->";;
node=node->next;
}
cout<<endl;
}
void delete_evens() // delete the pages with even page_number
{
Page* first = head;
Page* q=NULL;
while(first != NULL)
{
if(first->page_number % 2 == 0)
{
if(q==NULL)
{
head=first->next;
first=first->next;
}
else
{
q->next=first->next;
first->next=NULL;
first=q->next;
}
}
else
{
if(q==NULL)
{
q=first;
first=first->next;
}
else
{
q=q->next;
first=first->next;
}
}
}
}
PageList(int pages) noexcept // consteructor
{
head = NULL;
for (int i=1;i<=pages;i++){
append(i, "(page" + to_string(i));
}
cout<< "Created PageList:" << endl;
printList(head,true);
delete_evens();
cout<< "Updated PageList:" << endl;
printList(head,true);
}
};
// -------------------------------------------------------------------
int main()
{
PageList list(50);
return 0;
}