Linked list implementation in C

Just thought of sharing the code i written to learn linked list implementation the day before my data structures model practical exam.

/*
 *      linkedlist.c
 *      
 *      Copyright 2009 Rag Sagar.V <ragsagar@gmail.com>
 *      
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *      
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *      
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *      MA 02110-1301, USA.
 */


#include <stdio.h>
#include <stdlib.h>

typedef struct list
{
	int data;
	struct list *next;
}LIST;
LIST *ptr,*temp,*start=NULL;
void insert_after(int ,int );
void remove_item(int );
void display(void);
int count=0;
int main()
{
	int item,opt,dat;
	system("clear");
	ptr=NULL;
	/* printf("%d",sizeof(LIST)); */
	do
	{
		printf("\n########## MENU ##########\n");
		printf("1.Insert\n2.Remove\n3.Display\n4.Exit\n");
		printf("Enter your option : ");
		scanf("%d",&opt);
	 	switch(opt)
	 	{
	 		case 1:
	 		printf("Enter the data to insert ");
	 		scanf("%d",&item);
	 		if(count==0)
	 		{
	 			ptr = (LIST *)malloc(sizeof(LIST));
	 			ptr->next = NULL;
	 			ptr->data = item;
	 			start = ptr;
			}
			else
			{
				printf("Enter the item after which you have to insert new element : ");
				scanf("%d",&dat);
				insert_after(dat,item);
			}
			count++;
				break;
	 		case 2: 
	 		if(count==0)
	 		{
	 			printf("\nList is empty\n"); break; 
			}
	 		printf("Enter the item to remove : ");
	 		scanf("%d",&item);
	 		remove_item(item);
	 		count--;
	 		break;
	 		case 3: 
	 		if(count==0)
	 		{
	 			printf("\nList is empty\n");
	 			break;
	 		}
	 		else
	 		{
	 			printf("List elements are \n"); display(); 
			}
			break;
	 		case 4: break;
		}
	}while(opt!=4);
	return 0;
}
void insert_after(int data, int item)
{	
	LIST *tmp;
	temp=(LIST *)malloc(sizeof(LIST));
	temp->data=item;
	ptr=start;
	
	while(ptr!=NULL)
	{
		if(ptr->data==data)
		{
			tmp=ptr->next;
			ptr->next=temp;
			temp->next=tmp;
			break;
		}
	ptr=ptr->next;	
	}
		
}	

void remove_item(int item)
{
	ptr=start;
	if(ptr->data == item)
	{
		start = ptr->next;
		free(ptr);
	}
	while(ptr->next!=NULL)
	{
		if((ptr->next)->data==item)
		{
			temp=ptr->next;
			ptr->next=(ptr->next)->next;
			free(temp);
			break;
		}
		ptr=ptr->next;
	}
}
			
void display()
{
	ptr = start;
	while(ptr!=NULL)
	{
		printf("%d -> ",ptr->data);
		ptr=ptr->next;
	}
}			

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