Program of the various operations on a dequeue

This is a simple C program of the various operation on a dequeue.

#include<stdio.h> void input_re(); void output_re(); void insert_rear(); void insert_front(); void delet_front(); void delet_rear(); void display(); int dq[50],n,ch,rear=-1,front=-1,d,x,i; main() { int ch,c; printf("\nEnter the size of deque:"); scanf("%d",&n); do{ printf(" MENU\n1.input restricted deque\n2.output restricted deque"); printf("\n enter the choice"); scanf("%d",&ch); switch(ch) { case 1: input_re(); break; case 2: output_re(); break; default: printf("\n Wrong option"); } printf("\n do you want to continue::"); scanf("%d",&c); }while(c==1); } void input_re() { int c; do { int ch; printf("MENU\n1.insert rear\n2.delete front\n3.delete rear\n4.display"); printf("\n enter the choice"); scanf("%d",&ch); switch(ch) { case 1: insert_rear(); break; case 2: delet_front(); break; case 3: delet_rear(); break; case 4: display(); break; default: printf("\n Wrong option"); } printf("\n do you want to continue the input restricted function :"); scanf("%d",&c); }while(c==1); } void output_re() { int ch,c; do { printf("menu\n1.insert rear\n2.insert front\n3.delet from front\n4.display"); printf(" enter the choice"); scanf("%d",&ch); switch(ch) { case 1: insert_rear(); break; case 2: insert_front(); break; case 3: delet_front(); break; case 4: display(); break; default: printf(" invalid option"); } printf("\n do you want to continue the output restricted function:"); scanf("%d",&c); }while(c==1); } void insert_rear() { printf("\n enter the element to be inserted"); scanf("%d",&x); if(((front==0)&&(rear==n-1))||(front==rear+1)) printf("\n deque overflow"); else if((front==-1)&&(rear==-1)) {front=0; rear=0; dq[rear]=x; } else rear=(rear+1)%n; dq[rear]=x; } void insert_front() { printf("\n enter the element to insert:"); scanf("%d",&x); if(((front==0)&&(rear==n-1))||(front==rear+1)) printf("\n deque is full"); else if((front==-1)&&(rear==-1)) front=rear=0; else { if(front==0) front=n-1; else front=front-1; dq[front]=x; }} void delet_front() { if((front==-1)&&(rear==-1)) printf("\n deque is empty"); else { if(front==rear) { front=-1; rear=-1; } else front++; } } void delet_rear() { if((front==-1)&&(rear==-1)) printf("\n deque is empty"); else { if(front==rear) { front=-1; rear=-1; } else { if(rear==0) rear=n-1; else rear=rear-1; } } } void display() { if((front==-1)&&(rear==-1)) printf("\n deque is empty"); else { if(front>rear) { for(i=front;i<n;i++) { d=dq[i]; printf("%d\t",d); } for(i=0;i<=rear;i++) { d=dq[i]; printf("%d\t",d); } } else { for(i=front;i<=rear;i++) { d=dq[i]; printf("%d\t",d); } } } }