Write a C program for Singly Linked List

#include<conio.h>
#include<stdio.h>

 struct node
 {
  int data;
  struct node *next;
  }*p;



/*THIS FUNCTION DELETES A NODE */

    struct 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("\n\nELEMENT %d NOT FOUND", num);
   }/*THIS FUNCTION ADDS A NODE AT THE LAST OF LINKED LIST */


   struct node 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("\n\ninsertion 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("\nNO ELEMENT IN THE LIST :\n");
     return;
    }
  /* traverse the entire linked list */
    while(r!=NULL)
    {
       printf(" -> %d ",r->data);
       r=r->next;
     }
     printf("");
    }
//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 */

main()
{
int i;
p=NULL;
clrscr();
while(1) /* this is an indefinite loop */
{
printf("\n1.INSERT A NUMBER AT BEGINNING");
printf("\n2.INSERT A NUMBER AT LAST:");
printf("\n3.INSERT A NUMBER AT A PARTICULAR LOCATION IN LIST");
printf("\n4.PRINT THE ELEMENTS IN THE LIST :");
printf("\n5.PRINT THE NUMBER OF ELEMENTS IN THE LIST ");
printf("\n6.DELETE A NODE IN THE LINKED LIST:");
printf("\n7.REVERSE A LINKED LIST :");
printf("\n8.GET OUT OF LINKED LIST (BYEE BYEE):");
printf("\n\nPLEASE, ENTER THE CHOICE: ");
scanf("%d",&i); /* ENTER A VALUE FOR SWITCH */

switch(i)
{
case 1:
{
int num;
printf("\nPLEASE ENTER THE NUMBER:- ");
scanf("%d",&num);
addbeg(num);
break;
}
case 2:
{
int num;
printf("\nPLEASE ENTER THE NUMBER:- ");
scanf("%d",&num);
append(num);
break;
}

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

case 5:
{
struct node *n;
display(n);
printf(" \nTOTAL NO OF ELEMENTS IN THE LSIT ARE %d\n",count());
break;
} case 6:
{
int num;
printf("\nPLEASE ENTER A NUMBER FROM THE LIST: ");
scanf("%d",&num);
delnode(num);
break;
}
case 7:
{
reverse(p);
display(p);
break;
}
case 8:
{
exit();
}
}/* end if switch */
}/* end of while */
}/* end of main */