Implementation os some some elementary operations like insert, delete, search on doubly circular linked list.
Code: C
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
#include <string.h>
#define N 100
struct dclinklist
{
struct dclinklist *prev; /** Stores address of previous node **/
int roll_no; /** stores roll number **/
char name[N]; /** stores Name **/
float marks; /** stores Marks **/
struct dclinklist *next; /** stores address of next node **/
};
/** Redefining dclinklist as node **/
typedef struct dclinklist node;
void init(node*); /** Input function **/
void ins_aft(node*); /** Function inserting before **/
node* ins_bef(node*); /** Function inserting after **/
node* del(node*); /** Function deleting a node **/
void search(node*); /** Function for searching node **/
void disp(node*); /** Function for displaying node **/
void rollsrch(node*); /** Function for searching node by roll number **/
void namesrch(node*); /** Function for searching node by name **/
void marksrch(node*); /** Function for searching node by marks **/
/*** Main Function ***/
void main()
{
node *head;
char ch; /* Choice inputing varible */
int opt; /* Option inputing variable*/
static int flag=0; /* Unchanged after iniialization */
clrscr();
head=(node*)malloc(sizeof(node));
head->next=NULL; /* NULL is being over written in init function */
head->prev=NULL;
do
{
again:
printf("\nEnter your option\n");
printf("\n1. Initialize the node\n");
printf("\n2. Insert before a specified node\n");
printf("\n3. Insert after a specified node\n");
printf("\n4. Delete a particular node\n");
printf("\n5. Search the nodes\n");
printf("\n6. Display all the nodes\n");
scanf("%d",&opt);
if(flag==0 && opt!=1)
{
printf("\nNo. You must first initialize at least one node\n");
goto again;
}
if(flag==1 && opt==1)
{
printf("\nInitialisation can occur only once.\n");
printf("\nNow you can insert a node\n");
goto again;
}
if(opt==4 && head->next==head)
{
printf("\nYou cannot delete the one and only the single node\n");
goto again;
}
if(flag==0 && opt==1)
flag=1;
switch(opt)
{
case 1:
init(head);
break;
case 2:
head=ins_bef(head);
break;
case 3:
ins_aft(head);
break;
case 4:
head=del(head);
break;
case 5:
search(head);
break;
case 6:
disp(head);
break;
}
printf("\nDo you wish to continue[y/n]\n");
ch=(char)getche();
}while(ch=='Y' || ch=='y');
printf("\nDone by \"SHABBIR\"\n");
printf("\nPress any key to exit\n");
getch();
}
/*** Function for inputing data ***/
void init(node *start)
{
start->prev=start;
printf("\nEnter Roll number\n");
scanf("%d",&start->roll_no);
printf("\nEnter the name\n");
fflush(stdin);
gets(start->name);
printf("\nEnter the marks\n");
scanf("%f",&start->marks);
start->next=start;
}
/*** Function for inserting a node after a specified node ***/
void ins_aft(node *start)
{
int rno; /* Roll number for inserting a node */
int flag=0;
node *newnode; /* New inputed node*/
node *current; /* Node for travelling the linked list*/
newnode=(node*)malloc(sizeof(node));
printf("\nEnter the roll number after which you want to insert a node\n");
scanf("%d",&rno);
init(newnode);
current=start;
while(current->next!=start)
{
/*** Insertion checking for all nodes except last ***/
if(current->roll_no==rno)
{
newnode->next=current->next;
current->next->prev=newnode;
current->next=newnode;
newnode->prev=current;
flag=1;
}
current=current->next;
}
if(flag==0 && current->next==start && current->roll_no==rno)
{
/*** Insertion checking for last node ***/
newnode->next=current->next; /* Start is being copied */
current->next->prev=newnode;
current->next=newnode;
newnode->prev=current;
flag=1;
}
if(flag==0 && current->next==NULL)
printf("\nNo match found\n");
}
/*** Function for inserting a node before a specified node ***/
node* ins_bef(node *start)
{
int rno; /* Roll number for inserting a node*/
node *newnode; /* New inputed node */
node *current; /* Node for travelling the linked list*/
newnode=(node*)malloc(sizeof(node));
printf("\nEnter the roll number before which you want to insert a node\n");
scanf("%d",&rno);
init(newnode);
current=start;
if(current->roll_no==rno)
{
/*** Insertion checking for first node ***/
newnode->next=current;
current->prev=newnode;
while(current->next!=start)
current=current->next;
newnode->prev=current;
current->next=newnode;
start=newnode;
return(start);
}
while(current->next!=start)
{
/*** Insertion checking for all node except first ***/
if(current->next->roll_no==rno)
{
newnode->next=current->next;
current->next->prev=newnode;
current->next=newnode;
newnode->prev=current;
return(start);
}
current=current->next;
}
/*
If the function does not return from any return statement.
There is no match to insert before the input roll number.
*/
printf("\nMatch not found\n");
return(start);
}
/*** Function for deleting a specified node ***/
node* del(node *start)
{
int rno; /* Roll number for deleting a node*/
node *delnode; /* Node to be deleted */
node *current; /* Node for travelling the linked list*/
printf("\nEnter the roll number whose node you want to delete\n");
scanf("%d",&rno);
current=start;
if(current->roll_no==rno)
{
/*** Checking condition for deletion of first node ***/
delnode=current; /* Unnecessary step */
while(current->next!=start)
current=current->next;
current->next=start->next;
start->next->prev=current;
start=start->next;
free(delnode);
return(start);
}
else
{
while(current->next->next!=start)
{
/*** Checking condition for deletion of ***/
/*** all nodes except first and last node ***/
if(current->next->roll_no==rno)
{
delnode=current->next;
current->next=current->next->next;
current->next->prev=current;
free(delnode);
return(start);
}
current=current->next;
}
if(current->next->next==start && current->next->roll_no==rno)
{
/*** Checking condition for deletion of last node ***/
delnode=current->next;
free(delnode);
current->next=start;
return(start);
}
}
printf("\nMatch not found\n");
return(start);
}
/*** Function for searching a node ***/
void search(node *start)
{
int ch; /* Choice inputing variable */
printf("\nEnter the criteria for search\n");
printf("\n1. Roll number\n");
printf("\n2. Name\n");
printf("\n3. Marks\n");
scanf("%d",&ch);
switch(ch)
{
case 1:
rollsrch(start);
break;
case 2:
namesrch(start);
break;
case 3:
marksrch(start);
break;
default:
rollsrch(start);
}
}
/*** Function for searching a specified roll number ***/
void rollsrch(node *start)
{
int rno; /* Roll-number to be searched */
node *current; /* Node for travelling the linked list*/
printf("\nEnter the roll number to search\n");
scanf("%d",&rno);
current=start;
while(current->next!=start)
{
if(current->roll_no==rno)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
current=current->next;
}
if(current->next==start && current->roll_no==rno)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
}
/*** Function for searching a specified name ***/
void namesrch(node *start)
{
char arr[20]; /* Name to be searched*/
node *current; /* Node for travelling the linked list*/
printf("\nEnter the name to search\n");
fflush(stdin);
gets(arr);
current=start;
while(current->next!=start)
{
if(strcmp(current->name,arr)==NULL)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
current=current->next;
}
if(current->next==start && strcmp(current->name,arr)==NULL)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
}
/*** Function for searching a specified marks ***/
void marksrch(node *start)
{
float marks; /* Marks to be searched */
node *current; /* Node for travelling the linked list*/
printf("\nEnter the marks to search\n");
scanf("%f",&marks);
current=start;
while(current->next!=start)
{
if(current->marks==marks)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
current=current->next;
}
if(current->next==start && current->marks==marks)
printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
}
/*** Function for displaying the linked list ***/
void disp(node *start)
{
node *current; /* Node for travelling the linked list*/
current=start;
while(current->next!=start)
{
printf("\n %d %s %f",current->roll_no,current->name,current->marks);
current=current->next;
}
printf("\n %d %s %f",current->roll_no,current->name,current->marks);
}
