Assignment 11

Assignmentno.:11
Title: Accept input as a string and construct a Doubly Linked List (DLL) for the input string with each node contains, as a data one character from the string and perform:
a) Insert b) delete c) Display forward, d) Display backward.
 
#include<stdio.h>
#include<string.h>
#include<malloc.h>
struct DLL
{
	struct DLL *prev;
	int roll_no;
	char name[10];
	float per;
	struct DLL *next;
};
struct DLL *create(struct DLL *start);
struct DLL *dele(struct DLL *start);
void modify(struct DLL *start);
void display(struct DLL *start);
void displayback(struct DLL *start);
int main()
  {
struct DLL *start=NULL;
 int ch;
  do
   {
  printf("\nMENU\n1.create\n2.Display forword\n3.modify\n4.dele\n5.display backword\n6.exit");
   printf("enter your choice");
    scanf("%d",&ch);
    switch(ch)
       {
          case 1:start=create(start);
           break;
          case 2:display (start);
          break;
         case 3:modify(start);
           break;
          case 4:start=dele(start);
           break;
          case 5:displayback(start);
          break;
        }
    }while(ch!=6);
  }    







struct DLL *create(struct DLL *start)
{
	struct DLL *p,*q;
	int i,r,n;
	char stud_name[10];
	float stud_per;
	printf("\nEnter how many nodes to create:");
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		printf("Enter student roll no:");
		scanf("%d",&r);
		printf("Enter student name:");
		scanf("%s",stud_name);
		printf("Enter student percentage:");
		scanf("%f",&stud_per);
		p=(struct DLL *)malloc(sizeof(struct DLL));
		p->roll_no=r;
		strcpy(p->name,stud_name);
		p->per=stud_per;
		p->prev=NULL;
		p->next=NULL;
		if(start==NULL)
		{
			start=p;
		}
		else
		{
			q=start;
			while(q->next!=NULL)
			{
				q=q->next;
			}
			p->prev=q;
			q->next=p;
		}
	}
	display(start);
	return(start);
}


void display(struct DLL *start)
{
	struct DLL *q;
	if(start==NULL)
	{
		printf("\nLIST IS EMPTY");
	}
	else
	{
		q=start;
		printf("\n\tROLL NO\tNAME\tPERCENTAGE\n");
		while(q!=NULL)
		{
			printf("\n\t%d\t%s\t%f",q->roll_no,q->name,q->per);
			q=q->next;
		}
	}
}


void displayback(struct DLL *start)
{
	struct DLL *q;
	if(start==NULL)
	{
		printf("\nLIST IS EMPTY");
	}
	else
	{
		q=start;
		while(q->next!=NULL)
		{
		    q=q->next;
		}
		printf("\n\tROLL NO\tNAME\tPERCENTAGE\n");
		while(q!=NULL)
		{
			printf("\n\t%d\t%s\t%f",q->roll_no,q->name,q->per);
			q=q->prev;
		}
	}
}

struct DLL *dele(struct DLL *start)
{
	struct DLL *q;
	int r;
	printf("\nEnter the roll no of student to dele:");
	scanf("%d",&r);
	if(start==NULL)
	{
		printf("\nLIST IS EMPTY");
	}
	q=start;
	while(q->roll_no!=r && q!=NULL)
	{
		q=q->next;
	}
	if(q!=NULL)
	{
		q->prev->next=q->next;
		q->next->prev=q->prev;
		free(q);
	}
	display(start);
	return(start);

}



void modify(struct DLL *start)
{
	struct DLL *q;
	int i,r,n;
	char stud_name[10];
	float stud_per;
	printf("\nEnter the roll no of student to modify:");
	scanf("%d",&r);
	if(start==NULL)
	{
		printf("\nLIST IS EMPTY");
	}
	q=start;
	while(q->roll_no!=r && q!=NULL)
	{
		q=q->next;
	}
	if(q->roll_no==r)
	{
		printf("Enter new roll no:");
		scanf("%d",&r);
		printf("Enter new name:");
		scanf("%s",stud_name);
		printf("Enter new percentage:");
		scanf("%f",&stud_per);
		q->roll_no=r;
		strcpy(q->name,stud_name);
		q->per=stud_per;
	}
	else
	{
		printf("NOT FOUND");
	}
	display(start);
}