queue.cpp

#include<iostream>
#include<algorithm>
using namespace std;

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

class Qlist{

	Node *front, *rear;
	
public:
	Qlist(){
		front = rear = NULL;
	}
	bool isEmpty();
	void insert(int);
	void del();
	void display();
};

bool Qlist:: isEmpty(){
	if(front==NULL && rear==NULL) return true;
	return false;
}

void Qlist:: insert(int item){
	Node *curr = new Node;
	if(curr==NULL){
		cout<<"Heap Full"<<endl;
		return;
	}
	curr->data=item;
	curr->next=NULL;
	if(rear==NULL){
		front=rear=curr;
		return;
	}
	rear->next=curr;
	rear=curr;
}

void Qlist::del(){
	Node *temp=front;
	front=front->next;
	delete temp;
	temp=NULL;
}

void Qlist:: display(){
	if(!isEmpty()){
		Node *temp=front;
		while(temp!=NULL){
			cout<<temp->data<<" ";
			temp=temp->next;
		}
	}
	return;
}



int main(){
	Qlist ql;
	int choice,item;
	while(true){
		cout<<"\n\n";
		cout<<"Press 1 to check if Queue is empty"<<endl;
		cout<<"Press 2 to push an item to Queue"<<endl;
		cout<<"Press 3 to pop an item from Queue"<<endl;
		cout<<"Press 4 to display the Queue"<<endl;
		cout<<"Enter choice ->";
		cin>>choice;
		
		switch(choice){
			case 1: if(ql.isEmpty()==0) cout<<"False"<<endl;
					else cout<<"True"<<endl;
					break;
					
			case 2: cout<<"Enter an item ->";
					cin>>item;
					ql.insert(item);
					break;
					
			case 3: ql.del();
					break;
					
			case 4: cout<<"The Queue ->";
					ql.display();
					break;
					
			default:cout<<"Invalid Choice"<<endl; 
					exit(0);
					
		}
	}


}