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Double Linked List

Discussion in 'C' started by shabbir, Aug 27, 2006.

  1. C implementation of double linked list
    Code:
    #include <stdio.h>
    #include <conio.h>
    #include <stdlib.h>
    #include <string.h>
    #define N 100
    
    struct dlinklist
    {
    	struct dlinklist *prev;  /** Stores address of previous node **/
    	int roll_no;			 /** stores roll number **/
    	char name[N];            /** stores Name **/
    	float marks;             /** stores Marks **/
    	struct dlinklist *next;  /** stores address of next node **/
    };
    
    /** Redefining dlinklist as node **/
    typedef struct dlinklist 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 **/
    
    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;
    	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==NULL)
    	{
    		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=getche();
    	}while(ch=='Y' || ch=='y');
    	printf("\nDone by \"SHABBIR\"\n");
    	printf("\nPress any key to exit\n");
    	getch();
    }
    
    void init(node *current)
    {
    	current->prev=NULL;
    	printf("\nEnter Roll number\n");
    	scanf("%d",&current->roll_no);
    	printf("\nEnter the name\n");
    	fflush(stdin);
    	gets(current->name);
    	printf("\nEnter the marks\n");
    	scanf("%f",&current->marks);
    	current->next=NULL;
    }
    
    void ins_aft(node *current)
    {
    	int rno;             /* Roll number for inserting a node*/
    	int flag=0;
    	node *newnode;
    	newnode=(node*)malloc(sizeof(node));
    	printf("\nEnter the roll number after which you want to insert a node\n");
    	scanf("%d",&rno);
    	init(newnode);
    	while(current->next!=NULL)
    	{
    		/***  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==NULL && current->roll_no==rno)
    	{
    		/***  Insertion checking for last nodes  ***/
    		newnode->next=current->next;
    		current->next=newnode;
    		flag=1;
    	}
    	else if(flag==0 && current->next==NULL)
    		printf("\nNo match found\n");
    }
    
    node* ins_bef(node *current)
    {
    	int rno;            /* Roll number for inserting a node*/
    	node *newnode,*temp;
    	newnode=(node*)malloc(sizeof(node));
    	printf("\nEnter the roll number before which you want to insert a node\n");
    	scanf("%d",&rno);
    	init(newnode);
    	if(current->roll_no==rno)
    	{
    		/*** Insertion checking for first node ***/
    		newnode->next=current;
    		current->prev=newnode;
    		current=newnode;
    		return(current);
    	}
    	temp=current;
    	while(temp->next!=NULL)
    	{                                       
    		/*** Insertion checking for all node except first ***/
    		if(temp->next->roll_no==rno)
    		{
    			newnode->next=temp->next;
    			temp->next->prev=newnode;
    			temp->next=newnode;
    			newnode->prev=temp;
    			return(current);
    		}
    		temp=temp->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(current);
    }
    
    node* del(node *current)
    {
    	int rno;               /* Roll number for deleting a node*/
    	node *newnode,*temp;
    	printf("\nEnter the roll number whose node you want to delete\n");
    	scanf("%d",&rno);
    	newnode=current;
    	if(current->roll_no==rno)
    	{
    		/***  Checking condition for deletion of first node  ***/
    		newnode=current; /*  Unnecessary step  */
    		current=current->next;
    		current->prev=NULL;
    		free(newnode);
    		return(current);
    	}
    	else
    	{
    		while(newnode->next->next!=NULL)
    		{
    			/***  Checking condition for deletion of   ***/
    			/*** all nodes except first and last node  ***/
    			if(current->next->roll_no==rno)
    			{
    				newnode=current;
    				temp=current->next;
    				newnode->next=newnode->next->next;
    				newnode->next->prev=current;
    				free(temp);
    				return(current);
    			}
    			newnode=newnode->next;
    		}
    		if(newnode->next->next==NULL && newnode->next->roll_no==rno)
    		{
    			/***  Checking condition for deletion of last node  ***/
    			temp=newnode->next;
    			free(temp);
    			newnode->next=NULL;
    			return(current);
    		}
    	}
    	printf("\nMatch not found\n");
    	return(current);
    }
    
    void search(node *current)
    {
    	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(current);
    		break;
    	case 2:
    		namesrch(current);
    		break;
    	case 3:
    		marksrch(current);
    		break;
    	default:
    		rollsrch(current);
    	}
    }
    
    void rollsrch(node *current)
    {
    	int rno;
    	printf("\nEnter the roll number to search\n");
    	scanf("%d",&rno);
    	while(current->next!=NULL)
    	{
    		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==NULL && current->roll_no==rno)
    		printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
    }
    
    void namesrch(node *current)
    {
    	char arr[20];
    	printf("\nEnter the name to search\n");
    	fflush(stdin);
    	gets(arr);
    	while(current->next!=NULL)
    	{
    		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==NULL && strcmp(current->name,arr)==NULL)
    		printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
    }
    
    void marksrch(node *current)
    {
    	float marks;
    	printf("\nEnter the marks to search\n");
    	scanf("%f",&marks);
    	while(current->next!=NULL)
    	{
    		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==NULL && current->marks==marks)
    		printf("\n%d\t%s\t%f\n",current->roll_no,current->name,current->marks);
    }
    
    void disp(node *current)
    {
    	while(current!=NULL)
    	{
    		printf("\n%d\t%s\t%f",current->roll_no,current->name,current->marks);
    		current=current->next;
    	}
    }
    
     
  2. rahul.mca2001

    rahul.mca2001 New Member

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    well explained
     
  3. sateshb

    sateshb New Member

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    hey dude my question is that if a read a name in from a file and i want to add it to the linked list how do i do that ?

    typedef struct list{
    name[30];
    struct *next, *prev;
    }

    in my add function i wanna add a my name "satesh" but get if from a file.
    Won't work if i have i had:
    ...... myName[10] = "satesh"
    head->name = myName; .......

    help !
     
  4. prabakongu

    prabakongu New Member

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    student
    Location:
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    hi.......sir........i little bit know only poiter........so now i have confuesd........pls give me full explantion in doubly linked list................
     

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