Queue using Array in C++

What Is Queue ???

A queue is an ordered list in which all insertions take place at one end, the rear, while all deletions take place at the other end, the front. All Queue Operation like insertion , deletion or display as elements can understand by following Program.

Source Code :

#include<conio.h> #include<iostream.h> #include<stdio.h> #define max 6 int q[10],rear=-1,front=-1; void insertInQ(int data) { if(rear==-1&&front==-1) { rear=0; front=0; q[rear]=data; return;   } if(front==0&&rear==max-1||front==rear+1) { cout<<"overflow"; return; } if(rear==max-1) rear=0; else rear=rear+1; q[rear]=data; }   int deleteFromQ(){ int data; if(front==-1&&rear==-1) { cout<<"underflow"; return 0; }   data=q[front]; q[front]=NULL;   if(front==rear) { front=rear=-1; } else { if(front==max-1) front=0; else front=front+1; } return data;   } void printQ() { int i; for(i=0;i<max;i++) { if(q[i]==NULL) cout<<"t"; else cout<<"t"<<q[i]; } } int main() { int ch,d; while(1) { cout<<"n=========queue operations===========n 1.insert n 2.delete n 3.show n 4.exit n ========================= n Enter your choice : " ; cin>>ch; switch(ch) { case 1 :   cout<<"n enter data :" ; cin>>d; insertInQ(d); break;   case 2: d=deleteFromQ(); cout<<"n data is :"<<d; break;   case 3: printQ(); break;   case 4: exit(0);   default : cout<<"n wrong choice------ n"; break; } } getch(); return 0; }

Output :