C Exercises: Create and display a doubly linked list

C Doubly Linked List : Exercise-1 with Solution

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

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 displayDlList();

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

    printf(" Input the number of nodes : ");
    scanf("%d", &n);

    DlListcreation(n); // Create a doubly linked list
    displayDlList();   // Display the created doubly linked list
    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
void displayDlList() {
    struct node *tmp;
    int n = 1;
    if (stnode == NULL) {
        printf(" No data found in the List yet.");
    } else {
        tmp = stnode;
        printf("\n\n Data entered on the list are :\n");

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

Sample Output:

 Doubly Linked List : Create and display a doubly linked list :                                               
-------------------------------------------------------------------                                           
 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 entered on the list are :                                                                               
 node 1 : 2                                                                                                   
 node 2 : 5                                                                                                   
 node 3 : 8

Flowchart:

DlListcreation() :

displayDlList() :

C Programming Code Editor:

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