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

C Doubly Linked List : Exercise-2 with Solution

Write a program in C to create a doubly linked list and display it in reverse order.

Visual Presentation:

Sample Solution:

C Code:

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

// Structure for a doubly linked list node
struct node {
    int num;
    struct node *preptr;
    struct node *nextptr;
} *stnode, *ennode;

// Function prototypes
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);     // Create a doubly linked list
    displayDlListRev();    // Display the created doubly linked list in reverse order
    return 0;
}

// Function to create a doubly linked list
void DlListcreation(int n) {
    int i, num;
    struct node *fnNode;

    if (n >= 1) {
        stnode = (struct node *)malloc(sizeof(struct node)); // Allocate memory for the first node

        if (stnode != NULL) {
            printf(" Input data for node 1 : ");
            scanf("%d", &num);

            stnode->num = num;
            stnode->preptr = NULL;
            stnode->nextptr = NULL;
            ennode = stnode; // Assign stnode as the last node

            // Create nodes and link them to form the doubly linked list
            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;
                    fnNode->nextptr = NULL;

                    ennode->nextptr = fnNode;
                    ennode = fnNode;
                } else {
                    printf(" Memory can not be allocated.");
                    break;
                }
            }
        } else {
            printf(" Memory can not be allocated.");
        }
    }
}

// Function to display the doubly linked list in reverse order
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");

        // Traverse the list in reverse and display each node's data
        while (tmp != NULL) {
            printf(" Data in node %d : %d\n", n + 1, tmp->num);
            n++;
            tmp = tmp->preptr; // Move to the previous node
        }
    }
}

Sample Output:

 Doubly Linked List : Create and display a doubly linked list in reverse order :                              
------------------------------------------------------------------------------------                          
 Input the number of nodes : 3                                                                                
 Input data for node 1 : 2                                                                                    
 Input data for node 2 : 5                                                                                    
 Input data for node 3 : 8                                                                                    
                                                                                                              
 Data in reverse order are :                                                                                  
 Data in node 1 : 8                                                                                           
 Data in node 2 : 5                                                                                           
 Data in node 3 : 2 

Flowchart:

DlListcreation() :

displayDlListRev() :

C Programming Code Editor:

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