IMPLEMENTATION OF DEQUEUE USING SINGLY LINKED LIST

#include<stdio.h>
#include<conio.h>
#define pf printf
#define sf scanf
struct node
{
int info;
struct node *next;
}*front,*temp,*rear,*ptr;
void insertr()
{
temp=(struct node*)malloc(sizeof(struct node));
pf("\nEnter elemet: ");
sf("%d",&temp->info);
temp->next=NULL;
if(front==NULL && rear==NULL)
{
front=rear=temp;
return;
}
rear->next=temp;
rear=rear->next;
}
void delf()
{
if(front==NULL)
{
pf("\nEmpty Deque\n");
return;
}
if(front==rear && front!=NULL)
{
ptr=front;
front=rear=NULL;
free(ptr);
}
else
{
ptr=front;
front=front->next;
free(ptr);
}
}
void insertf()
{
temp=(struct node*)malloc(sizeof(struct node));
pf("\nEnter element: ");
sf("%d",&temp->info);
if(front==NULL && rear==NULL)
{
front=rear=temp;
temp->next=NULL;
return;
}
temp->next=front;
front=temp;
}
void delr()
{
if(rear==front && rear==NULL)
{
pf("Empty DEQUE");
getch();
return;
}
else if(rear==front)
{
rear=front=NULL;
free(rear);
free(front);
}
else
{
ptr=front;
while(ptr->next!=NULL)
{
temp=ptr;
ptr=ptr->next;
}
temp->next=NULL;
free(ptr);
rear=temp;
}
}
void show()
{
if(front==NULL && rear==NULL)
{
pf("\nEmpty Deque\n");
return;
}
ptr=front;
while(ptr!=NULL)
{
pf("%d\t",ptr->info);
ptr=ptr->next;
}
}
void main()
{
int ch;
clrscr();
while(1)
{
clrscr();
pf("\n1. Insert at rear");
pf("\n2. Insert at Front");
pf("\n3. Delete from front");
pf("\n4. Delete from rear");
pf("\n5. Show");
pf("\n6. Exit");
pf("\nEnter ur choice: ");
sf("%d",&ch);
switch (ch)
{
case 1: insertr(); break;
case 2: insertf(); break;
case 3: delf(); break;
case 4: delr(); break;
case 5: show(); break;
case 6: exit(0); break;
default: pf("Invalid option");
}
}
}