Question

Add the following methods to the singly list implementation below.

int size(); // Returns the number of nodes in the linked list
bool search(string query); // Returns if the query is present in the list
void add(List& l); // // Adds elements of input list to front of "this" list (the list that calls the add method)

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

// slist.cpp

#include <string>
#include "slist.h"

using namespace std;

Node::Node(string element) : data{element}, next{nullptr} {}

List::List() : first{nullptr} {}

// Adds to the front of the list
void List::pushFront(string element) {
Node* new_node = new Node(element);
if (first == nullptr) {// List is empty
first = new_node;
} else {
new_node->next = first;
first = new_node;
}
}

Iterator List::begin() {
Iterator iter;
iter.position = first;
iter.container = this;
return iter;
}

Iterator List::end() {
Iterator iter;
iter.position = nullptr;
iter.container = this;
return iter;
}

// Returns number of elements in the list
int List::size() {
// Q1: Your code here

}

// Returns if query is present in list (true/false)
bool List::search(string query) {
// Q2: Your code here

}

// Adds elements of input list to front of "this" list
void List::add(List& l) {
// Q3. Your code here

}

Iterator::Iterator() {
position = nullptr;
container = nullptr;
}

string Iterator::get() const {
return position->data;
}

void Iterator::next() {
position = position->next;
}

bool Iterator::equals(Iterator other) const {
return position == other.position;
}

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Use the following header file, and test program (not to be modified or uploaded!) to verify that your methods works correctly. The expected output is indicated slist.cpp

Note:

1. Please make sure to implement one method at a time (compile, and test). Comment out the unimplemented methods as you work along.

2. Please be sure to check that the code uploaded is indeed the one you intended to upload.

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------

// slist.h file

/* Singly linked list */
#ifndef LIST_H
#define LIST_H

#include <string>

using namespace std;

class List;
class Iterator;

class Node
{
public:
Node(string element);
private:
string data;
Node* previous;
Node* next;
friend class List;
friend class Iterator;
};

class List
{
public:
List();
void pushFront(string element);
Iterator begin();
Iterator end();
int size();
bool search(string query);
void add(List& l);
private:
Node* first;
friend class Iterator;
};

class Iterator
{
public:

Iterator();
string get() const;
void next();
bool equals(Iterator other) const;
private:
Node* position;
List* container;
friend class List;
};

#endif

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

// slist_test.cpp

#include <string>
#include <iostream>
#include "slist.h"

using namespace std;

int main()
{
List names1;

names1.pushFront("Alice");
names1.pushFront("Bob");
names1.pushFront("Carol");
names1.pushFront("David");

// names1 is now - David Carol Bob Alice

int numele = names1.size(); // Q1: TO BE COMPLETED
cout << "Number of elements in the list: " << numele << endl;

string query = "Eve";
bool present = names1.search(query); // Q2: TO BE COMPLETED
if (present) {
cout << query << " is present" << endl;
} else {
cout << query << " is absent" << endl;
}

List names2;
names2.pushFront("Eve");
names2.pushFront("Fred");

// names2 is now - Fred Eve

// Insert each element of input list (names1) to front of calling list (names2)
names2.add(names1); // Q3: TO BE COMPLETED

// Print extended list
// Should print - Alice Bob Carol David Fred Eve
for (Iterator pos = names2.begin(); !pos.equals(names2.end()); pos.next()) {
cout << pos.get() << " ";
}
cout << endl;
return 0;
}

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Thank you for your time and help

Answer 1

#######################################
            main.cpp
#######################################
#include <string>

#include <iostream>

#include "slist.h"

using namespace std;

int main()

{

List names1;

names1.pushFront("Alice");

names1.pushFront("Bob");

names1.pushFront("Carol");

names1.pushFront("David");

// names1 is now - David Carol Bob Alice

int numele = names1.size(); // Q1: TO BE COMPLETED

cout << "Number of elements in the list: " << numele << endl;

string query = "Eve";

bool present = names1.search(query); // Q2: TO BE COMPLETED

if (present) {

cout << query << " is present" << endl;

} else {

cout << query << " is absent" << endl;

}

List names2;

names2.pushFront("Eve");

names2.pushFront("Fred");

// names2 is now - Fred Eve

// Insert each element of input list (names1) to front of calling list (names2)

names2.add(names1); // Q3: TO BE COMPLETED

// Print extended list

// Should print - Alice Bob Carol David Fred Eve

for (Iterator pos = names2.begin(); !pos.equals(names2.end()); pos.next()) {

cout << pos.get() << " ";

}

cout << endl;

return 0;

}



#######################################
           slist.cpp
#######################################
#include <string>

#include "slist.h"

using namespace std;

Node::Node(string element) : data(element), next(nullptr) {}

List::List() : first(nullptr) {}

// Adds to the front of the list

void List::pushFront(string element) {

Node* new_node = new Node(element);

if (first == nullptr) {// List is empty

first = new_node;

} else {

new_node->next = first;

first = new_node;

}

}

Iterator List::begin() {

Iterator iter;

iter.position = first;

iter.container = this;

return iter;

}

Iterator List::end() {

Iterator iter;

iter.position = nullptr;

iter.container = this;

return iter;

}

// Returns number of elements in the list

int List::size() {
        int count = 0;
        Node *start = first;
        while(start != nullptr) {
                count++;
                start = start->next;
        }
        return count;
}

// Returns if query is present in list (true/false)
bool List::search(string query) {
        Node *start = first;
        while(start != nullptr) {
                if(start->data == query) {
                        return true;
                }
                start = start->next;
        }
        return false;
}

// Adds elements of input list to front of "this" list
void List::add(List& l) {
        Node *start = l.first;
        while(start != nullptr) {
                pushFront(start->data);
                start = start->next;
        }
}

Iterator::Iterator() {

position = nullptr;

container = nullptr;

}

string Iterator::get() const {

return position->data;

}

void Iterator::next() {

position = position->next;

}

bool Iterator::equals(Iterator other) const {

return position == other.position;

}



#######################################
             slist.h
#######################################
/* Singly linked list */
#ifndef LIST_H
#define LIST_H

#include <string>

using namespace std;

class List;
class Iterator;

class Node {

public:

Node(string element);

private:

string data;

Node* previous;

Node* next;

friend class List;

friend class Iterator;

};

class List

{

public:

List();

void pushFront(string element);

Iterator begin();

Iterator end();

int size();

bool search(string query);

void add(List& l);

private:

Node* first;

friend class Iterator;

};

class Iterator

{

public:

Iterator();

string get() const;

void next();

bool equals(Iterator other) const;

private:

Node* position;

List* container;

friend class List;

};

#endif

**************************************************

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