Linked list program with all functions

/* PROGRAM IMPLEMENTATION OF SINGLE LINKED LIST */


#include<stdio.h>
#include<conio.h>
//#define NULL 0


/* STRUCTURE CONTANING A DATA PART AND A LINK PART */
struct node
{
int data;
struct node *next;
}*p;


/* P IS A GLOBAL POINTER CONTAINS THE ADRESS OF THE FIRST NODE IN 
LIST
*/


/*THIS FUNCTION DELETES A NODE */
delnode(int num)
{
struct node *temp, *m;
temp=p;
while(temp!=NULL)
{
if(temp->data==num)
{
if(temp==p)
{
p=temp->next;
free(temp);
return;
}
else
{
m->next=temp->next;
free(temp);
return;
}
}else
{
m=temp;
temp= temp->next;
}


}
printf("ELEMENT %d NOT FOUND ", num);
}


/*THIS FUNCTION ADDS A NODE AT THE LAST OF LINKED LIST */
append( int num )
{
struct node *temp,*r;


/* CREATING A NODE AND ASSIGNING A VALUE TO IT */
temp= (struct node *)malloc(sizeof(struct node));
temp->data=num;
r=(struct node *)p;


if (p == NULL) /* IF LIST IS EMPTY CREATE FIRST NODE */
{
p=temp;
p->next =NULL;
}
else
{ /* GO TO LAST AND ADD*/
while( r->next != NULL)
r=r->next;
r->next =temp;
r=temp;
r->next=NULL;
}
}




/* ADD A NEW NODE AT BEGINNING */
addbeg( int num )
{




/* CREATING A NODE AND INSERTING VALUE TO IT */
struct node *temp;
temp=(struct node *)malloc(sizeof(struct node));
temp->data=num;


/* IF LIST IS NULL ADD AT BEGINNING */
if ( p== NULL)
{
p=temp;
p->next=NULL;
}


else
{
temp->next=p;
p=temp;
}
}


/* ADD A NEW NODE AFTER A SPECIFIED NO OF NODES */
addafter(int num, int loc)
{
int i;
struct node *temp,*t,*r;
r=p; /* here r stores the first location */
if(loc > count()+1 || loc <= 0)
{
printf("insertion is not possible :");
return;
}
if (loc == 1)/* if list is null then add at beginning */
{
addbeg(num);
return;
}
else
{
for(i=1;i<loc;i++)
{
t=r; /* t will be holding previous value */
r=r->next;
}
temp=(struct node *)malloc(sizeof(struct node));
temp->data=num;
t->next=temp;
t=temp;
t->next=r;
return;
}
}


/* THIS FUNCTION DISPLAYS THE CONTENTS OF THE LINKED LIST */
display(struct node *r)
{
r=p;
if(r==NULL)
{
printf("NO ELEMENT IN THE LIST :");
return;
}
/* traverse the entire linked list */
while(r!=NULL)
{
printf(" -> %d ",r->data);
r=r->next;
}
printf("\t");
}


/*THIS FUNCTION COUNTS THE NUMBER OF ELEMENTS IN THE LIST*/
count()
{
struct node *n;
int c=0;
n=p;
while(n!=NULL)
{
n=n->next;
c++;
}
return(c);
}




/*THIS FUNCTION REVERSES A LINKED LIST*/
reverse(struct node *q)
{
struct node *m, *n,*l,*s;
m=q;
n=NULL;
while(m!=NULL)
{
s=n;
n=m;
m=m->next;
n->next=s;
}
p=n;
}




/* THIS IS THE MAIN PROGRAM */
void main()
{
int i;
p=NULL;
while(1) 




/* this is an indefinite loop */
{
printf("\n1.INSERT A NUMBER AT BEGINNING;\t");
printf("\n2.INSERT A NUMBER AT LAST:\t");
printf("\n3.INSERT A NUMBER AT A PARTICULAR LOCATION INlIST:\t");
printf("\n4.PRINT THE ELEMENTS IN THE LIST :\t");
printf("\n5.PRINT THE NUMBER OF ELEMENTS IN THE LIST \t");
printf("\n6.DELETE A NODE IN THE LINKED LIST:\t");
printf("\n7.REVERSE A LINKED LIST :\t");
printf("\n8.GET OUT OF LINKED LIST (BYEE BYEE):\t");
printf("\nPLEASE, ENTER THE NUMBER:");


scanf("%d",&i);


/* ENTER A VALUE FOR SWITCH */
switch(i)
{
case 1:
{
int num;
printf("\nPLEASE ENTER THE NUMBER :-");
scanf("%d",&num);
addbeg(num);
 eak;
}
case 2:
{
int num;
printf("\nPLEASE ENTER THE NUMBER :-");
scanf("%d",&num);
append(num);
 eak;
}


case 3:
{
int num, loc,k;
printf("\nPLEASE ENTER THE NUMBER :-");
scanf("%d",&num);
printf("\nLEASE ENTER THE LOCATION NUMBER :-");
scanf("%d",&loc);
addafter(num,loc);
eak;
} 
case 4:
{
struct node *n;
printf("\nTHE ELEMENTS IN THE LIST ARE : \t");
display (n);
 eak;
}


case 5:


{
struct node *n;
display(n);
printf(" TOTAL NO OF ELEMENTS IN THE LSIT ARE %d",count());
 eak;
} case 6:
{
int num;
printf("\nPLEASE ENTER A NUMBER FROM THE LIST :");
scanf("%d",&num);
delnode(num);
 eak;
}
case 7:
{
reverse(p);
display(p);
 eak;
}
case 8:
{
exit();
}
}/* end if switch */
}/* end of while */
}/* end of main */