queue using Linked list

/* Program to implement queue using Linked list */
#include <stdio.h>
#include <conio.h>
#include <alloc.h>
#include <stdlib.h>
struct node
{
int info;
struct node *link;
};
struct node *front, *rear;

void main ( )
{
clrscr();
void insert(),delet(),display();
int ch;
while (1)
{
printf ("1. Insert\n");
printf ("2. Delete\n");
printf ("3. Display\n");
printf ("4. Exit\n");
printf ("Enter your choice :");
scanf ("%d", &ch);
switch (ch)
{
case 1 :
insert ( );
break;
case 2 :
delet( );
break;
case 3 :
display ( );
break;
case 4 :
exit(0);
default:
printf ("Please enter correct choice \n");
}
}
getch();
    }

void insert ( )
{
struct node *ptr;
ptr = (struct node*) malloc (sizeof (struct node));
int item;
printf ("Input the element for inserting :\n");
scanf ("%d", &item);
ptr-> info = item;
ptr->link = NULL;
if (front==NULL) /* queue is empty*/
front = ptr;
else
rear->link = ptr;
rear = ptr;
}
void delet( )
{
struct node *ptr;
if (front==NULL)
{
printf ("Queue is underflow \n");
return;
}
if (front==rear)
{
free (front);
rear = NULL;
}
else
{
ptr = front;
front = ptr->link;
free (ptr);
}
}
void display ( )
{
struct node *ptr;
ptr = front;
if (front==NULL)
printf("Queue is empty\n");
else
{
printf("\nElements in the Queue are:\n");
while(ptr!=NULL)
{
printf(" %d\n",ptr->info);
ptr=ptr->link;
}
printf("\n");
}
}