Single linked list

/*

Write a program for single linked list

*/

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

struct node

{

int info;

struct node *link;

};

struct node *create_list(struct node *start);

void display(struct node *start);

void count(struct node *start);

void search(struct node *start,int data);

struct node *addatbeg(struct node *start,int data);

struct node *addatend(struct node *start,int data);

struct node *addafter(struct node *start,int data,int item);

struct node *addbefore(struct node *start,int data,int item );

struct node *addatpos(struct node *start,int data,int pos);

struct node *del(struct node *start,int data);

struct node *reverse(struct node *start);

main()

{

struct node *start=NULL;

int choice,data,item,pos;

while(1)

{

printf("1.Create List\n");

printf("2.Display\n");

printf("3.Count\n");

printf("4.Search\n");

printf("5.Add to empty list / Add at beginning\n");

printf("6.Add at end\n");

printf("7.Add after node\n");

printf("8.Add before node\n");

printf("9.Add at position\n");

printf("10.Delete\n");

printf("11.Reverse\n");

printf("12.Quit\n\n");


printf("Enter your choice : ");

scanf("%d",&choice);


switch(choice)

{

case 1:

start=create_list(start);

break;

case 2:

display(start);

break;

case 3:

count(start);

break;

case 4:

printf("Enter the element to be searched : ");

scanf("%d",&data);

search(start,data);

break;

case 5:

printf("Enter the element to be inserted : ");

scanf("%d",&data);

start=addatbeg(start,data);

break;

case 6:

printf("Enter the element to be inserted : ");

scanf("%d",&data);

start=addatend(start,data);

break;

case 7:

printf("Enter the element to be inserted : ");

scanf("%d",&data);

printf("Enter the element after which to insert : ");

scanf("%d",&item);

start=addafter(start,data,item);

break;

case 8:

printf("Enter the element to be inserted : ");

scanf("%d",&data);

printf("Enter the element before which to insert : ");

scanf("%d",&item);

start=addbefore(start,data,item);

break;

case 9:

printf("Enter the element to be inserted : ");

scanf("%d",&data);

printf("Enter the position at which to insert : ");

scanf("%d",&pos);

start=addatpos(start,data,pos);

break;

case 10:

printf("Enter the element to be deleted : ");

scanf("%d",&data);

start=del(start, data);

break;

case 11:

start=reverse(start);

break;

case 12:

exit(1);

default:

printf("Wrong choice\n");

}
}
}

struct node *create_list(struct node *start)

{

int i,n,data;

printf("Enter the number of nodes : ");

scanf("%d",&n);

start=NULL;

if(n==0)

return start;

printf("Enter the element to be inserted : ");

scanf("%d",&data);

start=addatbeg(start,data);

for(i=2;i<=n;i++)

{

printf("Enter the element to be inserted : ");

scanf("%d",&data);

start=addatend(start,data);

}
return start;
}

void display(struct node *start)

{

struct node *p;

if(start==NULL)

{

printf("List is empty\n");

return;

}

p=start;

printf("List is :\n");

while(p!=NULL)

{

printf("%d ",p->info);

p=p->link;

}

printf("\n\n");

}

void count(struct node *start)

{

struct node *p;

int cnt=0;

p=start;

while(p!=NULL)

{

p=p->link;

cnt++;

}

printf("Number of elements are %d\n",cnt);

}

void search(struct node *start,int item)

{

struct node *p=start;

int pos=1;

while(p!=NULL)

{

if(p->info==item)

{

printf("Item %d found at position %d\n",item,pos);

return;

}

p=p->link;

pos++;

}

printf("Item %d not found in list\n",item);

}


struct node *addatbeg(struct node *start,int data)

{

struct node *tmp;

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

tmp->link=start;

start=tmp;

return start;

}

struct node *addatend(struct node *start,int data)

{

struct node *p,*tmp;

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

p=start;

while(p->link!=NULL)

p=p->link;

p->link=tmp;

tmp->link=NULL;

return start;

}

struct node *addafter(struct node *start,int data,int item)

{

struct node *tmp,*p;

p=start;

while(p!=NULL)

{

if(p->info==item)

{

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

tmp->link=p->link;

p->link=tmp;

return start;

}

p=p->link;

}

printf("%d not present in the list\n",item);

return start;

}

struct node *addbefore(struct node *start,int data,int item)

{

struct node *tmp,*p;

if(start==NULL )

{

printf("List is empty\n");

return start;

}

/*If data to be inserted before first node*/

if(item==start->info)

{

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

tmp->link=start;

start=tmp;

return start;

}

p=start;

while(p->link!=NULL)

{

if(p->link->info==item)

{

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

tmp->link=p->link;

p->link=tmp;

return start;

}

p=p->link;

}

printf("%d not present in the list\n",item);

return start;

}

struct node *addatpos(struct node *start,int data,int pos)

{

struct node *tmp,*p;

int i;

tmp=(struct node *)malloc(sizeof(struct node));

tmp->info=data;

if(pos==1)

{

tmp->link=start;

start=tmp;

return start;

}

p=start;

for(i=1; i<pos-1 && p!=NULL; i++)

p=p->link;

if(p==NULL)

printf("There are less than %d elements\n",pos);

else

{

tmp->link=p->link;

p->link=tmp;

}

return start;

}

struct node *del(struct node *start,int data)

{

struct node *tmp,*p;

if(start==NULL)

{

printf("List is empty\n");

return start;

}

/*Deletion of first node*/

if(start->info==data)

{

tmp=start;

start=start->link;

free(tmp);

return start;

}

/*Deletion in between or at the end*/

p=start;

while(p->link!=NULL)

{

if(p->link->info==data)

{

tmp=p->link;

p->link=tmp->link;

free(tmp);

return start;

}

p=p->link;

}

printf("Element %d not found\n",data);

return start;

}

struct node *reverse(struct node *start)

{

struct node *prev, *ptr, *next;

prev=NULL;

ptr=start;

while(ptr!=NULL)

{

next=ptr->link;

ptr->link=prev;

prev=ptr;

ptr=next;

}

start=prev;

return start;

}