Question

C++ ONLY -- PRACTICE ASSIGNMENT

For our practice assignment we have to turn in 2 files - Driver.cpp and StringQueue.h

Driver.cpp is provided for us, but if there are any changes needed to be made to that file please let me know.

Based on the instructions below, what should the code look like for StringQueue.h ?

1. Create a class named StringQueue in a file named StringQueue.h.
   
2. Create a QueueNode structure as a private member of the class. The node should be able to hold a string called value.   This should be like a ListNode structure that you have created before for linked lists.
   
3. Create a front pointer as private attributes of the class. (this is like the head pointer for a linked list)
4. Also create a rear pointer as a private attribute of the class. (this is like the tail pointer for a linked list)
5. Also create an integer named numItems, which will keep track with the number of items in the queue.
   
6. Create the following public member functions:
   1. A constructor, which will set front & rear to NULL and numItems to zero.
   2. An isEmpty function, which will return true if the queue is empty and false otherwise.
   3. A push_back function, which will push a string at the END of the queue (like appendNode function for linked list)
   4. A pop_front function, which will remove & return the string from the front of the queue.

7. Test your queue class using the Driver.cpp file provided for you.

PROVIDED Driver.cpp FILE:

#include <iostream>

#include "StringQueue.h"

using namespace std;

int main()

{

const int MAX_VALUES = 10;

//create the queue

StringQueue myQueue;

string candy;

cout << "\n\nMomma is going to buy us some candy!\n";

cout << "She may not let us buy all of it so lets make a queue \n";

cout << "and add our top 10 candy choices in the order from most favorite to \n";

cout << "least favorite so she will buy our most favorite first!!\n\n";

// User enters their fav candy

for (int x = 0; x < 10; x++)

{

cout << "CANDY " << x+1 << ": ";

getline(cin, candy);

myQueue.push_back(candy);

}

// Mom buys the candy

cout << "\nYay! Momma is home from the Piggly Wiggly! Here is the candy she bought:\n";

while (!myQueue.isEmpty())

{

candy = myQueue.pop_front();

cout << candy << endl;

}

cout << "\nYESSSSSS! She bought it all!\n\n";

return 0;

}

Answer 1

#include <string>
using namespace std;

struct QueueNode
{
    string value;
    QueueNode *next;
};

class StringQueue
{
    QueueNode *front,*rear;
    int numItems;
public:
    StringQueue()
    { 
        rear=NULL;
        front=NULL;
        numItems = 0;
    }
    bool isEmpty();
    void push_back(string s);
    string pop_front();
};

bool StringQueue::isEmpty(){
    if (numItems > 0 )
        return false;
    else 
        return true;
}

void StringQueue::push_back(string s)
{
    QueueNode *temp;
    temp = new QueueNode;
    temp->next = NULL;
    temp->value = s;
    if(rear == NULL)
    {
        rear = temp;
        front = temp;
    }
    else
    {
        rear->next=temp;
        rear=temp;
    }
    numItems++;
    //cout<<"Itempushed, no of items = "<<numItems<<"\n";
}

string StringQueue::pop_front()
{
    if(front!=NULL)
    {
        QueueNode *temp = front;
        string s = front->value;
        front = front->next;
        delete temp;
        if(front==NULL)
            rear=NULL;
        numItems--;
        //cout<<"Itempopped, no of items = "<<numItems<<"\n";
        return s;
    }
    else
        cout<<"Queue Empty..";
            
}

Above is the fully working code for StringQueue.h , just create a file with the same name and copy-paste the above code and you are done.

Below are the screenshots for the sample output and the code indentation.

Sample output

Please let me know if you have any questions/queries. Thanks.