Implement Double Link List operations

 

Implement a Double Link list using C language to perform basic operations that can be performed on Double Link List . Some of the Basic Double Link list operations that can be implemented on Double Link List are Given Below ….

• Create Double Link List
• Display Double Link list
  
• Delete Node
• Insert Node

Double Link list assignment is implemented as Fundamentals of Data structure(FDS) as Second Year (SE-IT) Assignment under Pune University and Mumbai University .

Double Link list Code

#include  
 #include  
 typedef struct link  
 {  
 char c;  
 struct link *lptr,*rptr;  
 }dll;  
 dll* alloc(char ch)  
 {  
 dll* f;  
 f=(dll*)malloc(sizeof(dll));  
 f->rptr=NULL;  
 f->lptr=NULL;  
 f->c=ch;  
 return f;  
 }  
 dll* freeall(dll *f)  
 {  
 dll* temp;  
 while(f!=NULL)  
 {  
 temp=f;  
 f=f->rptr;  
 f->rptr->lptr=NULL;  
 free(temp);  
 }  
 return f;  
 }  
 dll* create()  
 {  
  dll *f,*nw;  
  char x;  
  f=NULL;  
  printf("\n Enter a string :");  
  flushall();  
  while((x=getchar())!='\n')  
   {  
 if(f==NULL)  
 {  
  nw=alloc(x);  
  f=nw;  
 }  
 else  
  {  
  nw->rptr=alloc(x);  
  nw->rptr->lptr=nw;  
  nw=nw->rptr;  
  nw->rptr=NULL;  
  }  
   }  
  return(f);  
 }  
 void reverse(dll *f)  
 {  
 dll *p;  
 p=f;  
 if(p==NULL)  
 {  
 printf("\n Empty list");  
 return;  
 }  
 printf("\n\nInfo\tleft ptr\taddress\t\tright ptr");  
 while(p->rptr!=NULL)  
 p=p->rptr;  
 printf("\n%c\t%d\t\t%d\t\t%d",p->c,p->lptr,p,p->rptr);  
 do  
 {  
 p=p->lptr;  
 printf("\n%c\t%d\t\t%d\t\t%d",p->c,p->lptr,p,p->rptr);  
 }while(p!=f);  
 }  
 //DISPLAYING THE LINKED LIST  
 void display(dll *f)  
 {  
 dll *p;  
 p=f;  
 if(p==NULL)  
 {  
 printf("\n Empty list");  
 return;  
 }  
 printf("\n\nInfo\tleft ptr\taddress\t\tright ptr");  
 while(p!=NULL)  
 {  
 printf("\n%c\t%d\t\t%d\t\t%d",p->c,p->lptr,p,p->rptr);  
 p=p->rptr;  
 }  
 }  
 dll* del(dll *f,char ch)  
 {  
 dll *temp;  
 temp=f;  
 while((temp!=NULL)&&(temp->c!=ch))  
 temp=temp->rptr;  
 if(temp==NULL)  
 {  
 printf("THE CHARACTER IS NOT FOUND");  
 return f;  
 }  
 if(temp!=f)  
 temp->lptr->rptr=temp->rptr;  
 else  
 f=temp->rptr;  
 if(temp->rptr!=NULL)  
 temp->rptr->lptr=temp->lptr;  
 free(temp);  
 printf("THE CHARACTER HAS BEEN DELETED");  
 return f;  
 }  
 void insert_a(dll*f,char ch)  
 {  
 dll *nw;  
 char a;  
 while((f!=NULL)&&(f->c!=ch))  
 f=f->rptr;  
 if(f==NULL)  
 printf("VALUE NOT FOUND");  
 else  
 {  
 printf("ENTER CHARACTER TO BE INSERTED");  
 flushall();  
 scanf("%c",&a);  
 nw=alloc(a);  
 nw->lptr=f;  
 nw->rptr=f->rptr;  
 f->rptr=nw;  
 if(nw->rptr!=NULL)  
 nw->rptr->lptr=nw;  
 }  
 }  
 dll* insert_b(dll *f,char ch)  
 {  
 dll *nw,*temp;  
 char a;  
 temp=f;  
 while((f!=NULL)&&(f->c!=ch))  
 f=f->rptr;  
 if(f==NULL)  
 {  
 printf("VALUE NOT FOUND");  
 return f;  
 }  
 printf("ENTER CHARACTER TO BE INSERTED");  
 flushall();  
 scanf("%c",&a);  
 nw=alloc(a);  
 nw->rptr=f;  
 nw->lptr=f->lptr;  
 f->lptr=nw;  
 if(nw->lptr!=NULL)  
 nw->lptr->rptr=nw;  
 else  
 temp=nw;  
 return temp;  
 }  
 void main()  
 {  
 dll *f;  
 int ch,i;  
 char c;  
 do  
 {  
 clrscr();  
 printf("\n\t\t\t\tMAIN MENU");  
 printf("\n\t\t\t1.Create\n\t\t\t2.Display\n\t\t\t3.Delete a node");  
 printf("\n\t\t\t4.Insert a node\n\t\t\t5.Display backwards \n\t\t\t6.Exit");  
 printf("\n\nEnter your choice : ");  
 flushall();  
 scanf("%d",&ch);  
 switch(ch)  
 {  
 case 1:  
 f=create();  
 printf("THE LIST HAS BEEN CREATED");  
 getch();  
 break;  
 case 2:  
 display(f);  
 getch();  
 break;  
 case 3:  
 printf("ENTER THE CHARACTER TO BE DELETED");  
 flushall();  
 scanf("%c",&c);  
 f=del(f,c);  
 getch();  
 break;  
 case 4: do  
 {  
 clrscr();  
 printf("\n\t\t\t\tINSERT\n");  
 printf("\n\t\t\t1.AFTER A CHARACTER\n");  
 printf("\n\t\t\t2.BEFORE A CHARACTER\n");  
 printf("\n\t\t\t3.EXIT\n");  
 printf("ENTER YOUR CHOICE : ");  
 flushall();  
 scanf("%d",&ch);  
 if(ch==1||ch==2)  
 {  
 printf("Enter that character : ");  
 flushall();  
 scanf("%c",&c);  
 }  
 switch(ch)  
 {  
 case 1: insert_a(f,c);  
 printf("\nThe value is inserted\n");  
 getch();  
 break;  
 case 2: f=insert_b(f,c);  
 printf("\nThe value is inserted\n");  
 getch();  
 break;  
 case 3:  
 break;  
 default:  
 printf("Invalid,enter again\n");  
 getch();  
 }  
 }while(ch!=3);  
 break;  
 case 5:  
 reverse(f);  
 getch();  
 break;  
 case 6:  
 break;  
 default:  
 printf("Invalid choice");  
 getch();  
 }  
 }while(ch!=6);  
 }

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