QUEUE

A Queue is a FIFO (First In First Out) Structure

Unlike Stack Queue has two openings , Elements are added in one end and elements are removed from the other end.

For example we can compare this with the real world queue in which we stand to get train ticket (For Now lets ignore the online booking system). Whoever Stands in the Queue first gets the ticket first. The same Logic is used here also.

Here Front and Rear are the two ends.

#include <iostream>
using namespace std;
int queue[50];
int n = 50;
int front = - 1;
int rear = - 1;
void Queue_insertion() {
   int val;
   if (rear == n - 1)
      cout<<"Queue Overflow"<<endl;
   else {
    
      front = 0;
      cout<<" insert value in the queue : "<<endl;
      cin>>val;
      rear++;
      queue[rear] = val;
   }
}
void Delete() {
   if (front == - 1) {
      cout<<"Queue Underflow ";
   return ;
   } else {
      cout<<"Element deleted from queue is : "<< queue[front] <<endl;
      front++;;
   }
}
void Display_Queue () {
   if (front == - 1 )
   cout<<"Queue is empty"<<endl;
   else {
      cout<<"Queue elements are : ";
      for (int i = front; i <= rear; i++)
         cout<<queue[i]<<" ";
      cout<<endl;
   }
}
int main() {
   int ch;
   cout<<"1) insertion element to the queue"<<endl;
   cout<<"2) Delete element from queue"<<endl;
   cout<<"3) Display all the elements of queue"<<endl;
   cout<<"4) Exit"<<endl;
do {
   cout<<"Enter your choice : "<<endl;
   cin>>ch;
   switch (ch) {
      case 1: Queue_insertion();
         break;
      case 2: Delete();
         break;
      case 3: Display_Queue ();
         break;
      case 4: cout<<"Exit"<<endl;
         break;
      default: cout<<"Invalid choice"<<endl;
   }
} while(ch!=4);
   return 0;
}