Circular Linked List in C.
Circular linked list is a linked list whose last node points to the head of list.
Structure of Circular linked list
struct clnode{
int val;
struct clnode *next;
};
/*
*********** Circular List Menu ***********
[1] Insert value
[2] Print Circular List
[3] Print Length of list
[4] Insert at Beginning
[5] Delete front node
[6] Delete rear node
[7] Exit
*/
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/* C code for Circular Linked list by Codingstreet.com */ #include<stdio.h> #include<stdlib.h> struct clnode{ int val; struct clnode *next; }; int circular_length(struct clnode **head){ int count=0; struct clnode *tmp; tmp=(*head); if(tmp==NULL) return 0; do{ tmp=tmp->next; count++; }while(tmp!=(*head)); return count; } int create_clnode(int val,struct clnode **node){ struct clnode *tmp; tmp=malloc(sizeof(struct clnode)); if(tmp==NULL) return 0; tmp->val=val; tmp->next=NULL; (*node)=tmp; return 1; } void print_cl(struct clnode **head){ struct clnode *tmp; tmp=(*head); if(tmp==NULL) return; do{ printf(" %d ",tmp->val); tmp=tmp->next; }while(tmp!=(*head)); } void insert_clnode(struct clnode **head,struct clnode **node){ if((*head)==NULL) { (*node)->next=(*node); (*head)=(*node); return;} else { struct clnode *tmp; tmp=(*head); while(tmp->next!=(*head)){ tmp=tmp->next; } tmp->next=(*node); (*node)->next=(*head); } } void insert_atbeginclnode(struct clnode **head,struct clnode **node){ if((*head)==NULL) {(*node)->next=(*node); (*head)=(*node); return;} else { struct clnode *tmp; tmp=(*head); while(tmp->next!=(*head)){ tmp=tmp->next; } tmp->next=(*node); (*node)->next=(*head); (*head)=(*node); } } void delete_frontclnode(struct clnode **head){ struct clnode *tmp,*crnt; if((*head)==NULL) return; tmp=(*head); crnt=(*head)->next; if(crnt==(*head)){free(tmp); (*head)=NULL; return;} while(crnt->next!=(*head)) crnt=crnt->next; (*head)=(*head)->next; crnt->next=(*head); free(tmp); } void delete_rearclnode(struct clnode **head){ struct clnode *tmp,*prev;; if((*head)==NULL) return; tmp=(*head); prev=tmp; while(tmp->next!=(*head)){ prev=tmp; tmp=tmp->next; } if(tmp==(*head)) (*head)=NULL; tmp->next=NULL; free(tmp); prev->next=(*head); } int main(){ struct clnode *head=NULL,*node=NULL; int key,ival; do{ printf("\n*********** Circular List Menu ***********"); printf("\n[1] Insert value"); printf("\n[2] Print Circular List "); printf("\n[3] Print Length of list "); printf("\n[4] Insert at Begining "); printf("\n[5] Delete front node "); printf("\n[6] Delete rear node "); printf("\n[7] Exit "); printf("\nEnter the input key : "); scanf("%d",&key); switch(key){ case 1: printf("\n Enter the value to be inserted :"); scanf("%d",&ival); if(create_clnode(ival,&node)) insert_clnode(&head,&node); else printf("\n Memory is Full !! "); break; case 2: printf("\n Circular List contents are :\n"); print_cl(&head); break; case 3: printf("\n Lenght = %d ",circular_length(&head)); break; case 4 : printf("\n Enter the value to be inserted :"); scanf("%d",&ival); if(create_clnode(ival,&node)) insert_atbeginclnode(&head,&node); else printf("\n Memory is Full !! "); break; case 5 : delete_frontclnode(&head); break; case 6 : delete_rearclnode(&head); break; case 7 : break; default: printf("\t Enter the Correct key !!!!! "); break; } }while(key!=7); return 0; } |