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C Exercises: Create and display a doubly linked list in reverse order

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C Linked List : Exercise-12 with Solution

Write a program in C to create a doubly linked list and display in reverse order.
Test Data :
Input the number of nodes : 3
Input data for node 1 : 2
Input data for node 2 : 5
Input data for node 3 : 8
Expected Output :

 Data in reverse order are :                                                                                  
 Data in node 1 : 8                                                                                           
 Data in node 2 : 5                                                                                           
 Data in node 3 : 2 

C Code:

#include <stdio.h>
#include <stdlib.h>

struct node {
    int num;
    struct node * preptr;
    struct node * nextptr;
}*stnode, *ennode;
 

void DlListcreation(int n);
void displayDlListRev();

int main()
{
    int n;
    stnode = NULL;
    ennode = NULL;
	printf("\n\n Doubly Linked List : Create and display a doubly linked list in reverse order :\n");
	printf("------------------------------------------------------------------------------------\n");	   	

    printf(" Input the number of nodes : ");
    scanf("%d", &n);
 
    DlListcreation(n); 
    displayDlListRev();
    return 0;
}
 
void DlListcreation(int n)
{
    int i, num;
    struct node *fnNode;
 
    if(n >= 1)
    {
        stnode = (struct node *)malloc(sizeof(struct node));
 
        if(stnode != NULL)
        {
            printf(" Input data for node 1 : "); // assigning data in the first node
            scanf("%d", &num);
 
            stnode->num = num;
            stnode->preptr = NULL;
            stnode->nextptr = NULL;
            ennode = stnode;
// putting data for rest of the nodes
            for(i=2; i<=n; i++)
            {
                fnNode = (struct node *)malloc(sizeof(struct node));
                if(fnNode != NULL)
                {
                    printf(" Input data for node %d : ", i);
                    scanf("%d", &num);
                    fnNode->num = num;
                    fnNode->preptr = ennode;    // new node is linking with the previous node
                    fnNode->nextptr = NULL;
 
                    ennode->nextptr = fnNode;   // previous node is linking with the new node
                    ennode = fnNode;            // assign new node as last node
                }
                else
                {
                    printf(" Memory can not be allocated.");
                    break;
                }
            }
        }
        else
        {
            printf(" Memory can not be allocated.");
        }
    }
}

void displayDlListRev()
{
    struct node * tmp;
    int n = 0;
 
    if(ennode == NULL)
    {
        printf(" No data found in the List yet.");
    }
    else
    {
        tmp = ennode;
        printf("\n Data in reverse order are :\n");
        while(tmp != NULL)
        {
            printf(" Data in node %d : %d\n", n+1, tmp->num);
            n++;
            tmp = tmp->preptr; // current pointer set with previous node
        }
    }
} 

Flowchart :

Flowchart: Create and display a doubly linked list in revsese order

DlListcreation() :

Flowchart: Create and display a doubly linked list in revsese order

displayDlListRev() :

Flowchart: Create and display a doubly linked list in revsese order

C Practice online:


#include <stdio.h>
#include <stdlib.h>

struct node {
    int num;
    struct node * preptr;
    struct node * nextptr;
}*stnode, *ennode;
 

void DlListcreation(int n);
void displayDlListRev();

int main()
{
    int n;
    stnode = NULL;
    ennode = NULL;
	printf("\n\n Doubly Linked List : Create and display a doubly linked list in reverse order :\n");
	printf("------------------------------------------------------------------------------------\n");	   	

    printf(" Input the number of nodes : ");
    scanf("%d", &n);
 
    DlListcreation(n); 
    displayDlListRev();
    return 0;
}
 
void DlListcreation(int n)
{
    int i, num;
    struct node *fnNode;
 
    if(n >= 1)
    {
        stnode = (struct node *)malloc(sizeof(struct node));
 
        if(stnode != NULL)
        {
            printf(" Input data for node 1 : "); // assigning data in the first node
            scanf("%d", &num);
 
            stnode->num = num;
            stnode->preptr = NULL;
            stnode->nextptr = NULL;
            ennode = stnode;
// putting data for rest of the nodes
            for(i=2; i<=n; i++)
            {
                fnNode = (struct node *)malloc(sizeof(struct node));
                if(fnNode != NULL)
                {
                    printf(" Input data for node %d : ", i);
                    scanf("%d", &num);
                    fnNode->num = num;
                    fnNode->preptr = ennode;    // new node is linking with the previous node
                    fnNode->nextptr = NULL;
 
                    ennode->nextptr = fnNode;   // previous node is linking with the new node
                    ennode = fnNode;            // assign new node as last node
                }
                else
                {
                    printf(" Memory can not be allocated.");
                    break;
                }
            }
        }
        else
        {
            printf(" Memory can not be allocated.");
        }
    }
}

void displayDlListRev()
{
    struct node * tmp;
    int n = 0;
 
    if(ennode == NULL)
    {
        printf(" No data found in the List yet.");
    }
    else
    {
        tmp = ennode;
        printf("\n Data in reverse order are :\n");
        while(tmp != NULL)
        {
            printf(" Data in node %d : %d\n", n+1, tmp->num);
            n++;
            tmp = tmp->preptr; // current pointer set with previous node
        }
    }
} 

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