Question

C++

I need help to create a program that executes a simple queue data type. You must define the queue data type and use the enqueue(), dequeue(), and displayQueue() functions. (Dont use C++ STL to execute queue logic) You may use a linked list , or just use a regular C array of integers. The input file (testfile.txt) will be the list of operations to carry out on a queue.

Example input file:

enqueue 6
enqueue 8
dequeue
enqueue 4
enqueue 9
enqueue 8
dequeue
dequeue
dequeue

Sample output should look similar to this:

Enqueuing item: 6
Head: 6 :Tail
Enqueuing item: 8
Head: 6 8 :Tail
and so on.....

Answer 1

#include <iostream>
#include <string>
#include <fstream>

using namespace std;

struct Node {
   int data;
   Node *next;
};

class Queue {
   private:
       Node *head;
       Node *tail;
   public:
       Queue() {
           head = NULL;
           tail = NULL;
       }
       void enqueue(int data) {
           Node *n = new Node;
           n->data = data;
           n->next = NULL;
           if(head == NULL) {
               head = n;
               tail = n;
           } else {
               tail->next = n;
               tail = n;
           }
       }
       int dequeue() {
           int data = head->data;
           head = head->next;
           if(head == NULL) {
               tail = NULL;
           }
           return data;
       }
       void print() {
           Node *temp = head;
           cout << "Head: ";
           while(temp != NULL) {
               cout << temp->data << " ";
               temp = temp->next;
           }
           cout << ":Tail" << endl;
       }
};

int main() {
   string filename;
   cout << "Enter file name: ";
   cin >> filename;
   ifstream in(filename.c_str());
   if(in.is_open()) {
       string op;
       int data;
       Queue q;
       while(in >> op) {
           if(op == "enqueue") {
               in >> data;
               q.enqueue(data);
               cout << "Enqueuing item: " << data << endl;
           } else {
               cout << "Dequeuing item: " << q.dequeue() << endl;
           }
           q.print();
       }
       in.close();
   }
   else {
       cout << "can not open " << filename << " to read" << endl;
   }
   return 0;
}

Enter file name: input.txt Enqueuing item: 6 Head 6 Tail Enqueuing item: 8 Head 6 8 :Tail Dequeuing item: 6 Head 8 :Tail Enqueuing item: 4 ead 8 4 :Tail Enqueuing item: 9 ead 8 4 9 Tail Enqueuing item: 8 ead 8 4 9 8 :Tail Dequeuing item: 8 ead 4 9 8 Tail Dequeuing item: 4 Head 9 8 :Tail Dequeuing item: 9 Head 8 :Tail Process exited after 1.841 seconds with return ualue Press any key to continue .. .