C Program to reverse each node value in Singly Linked List

A linked list is a linear collection of data elements, in which each node points to the next node. Unlike an array, it doesn’t have upper limit and hence extremely useful. The task is to access value of each node of linked list and reverse them. 

Examples:

Input : 56 87 12 49 35
Output : 65 78 21 94 53

Input : 128 87 12433 491 33
Output : 821 78 33421 194 33

Algorithm: The task can be accomplished as:

1. Linearly traverse each node of the singly linked list.
2. Reverse the value of each node.
3. Store the reversed value in the current node.

Implementation:

C

// C program to reverse every node data in
// singly linked list.
#include <stdio.h>
#include <stdlib.h>

// A linked list node
struct Node {
    int data;
    struct Node* next;
};

// newNode function inserts the new node at
// the right side of linked list
struct Node* newNode(int key)
{
    struct Node* temp
        = (struct Node*)malloc(sizeof(struct Node));
    temp->data = key;
    temp->next = NULL;
    return temp;
}

// reverse() will receive individual data item
// from reverseIndividualData() and will return
// the reversed number to calling function
int reverse(int number)
{
    int new_num = 0, rem;

    while (number != 0) {
        rem = number % 10;
        new_num = new_num * 10 + rem;
        number = number / 10;
    }

    return new_num;
}

void reverseIndividualData(struct Node* node)
{

    if (node == NULL)
        return;

    while (node != NULL) {

        /*  function call to reverse(),
            reverseIndividualData(struct Node *node)
            will send the one data item at a time to
            reverse(node->data) function which will
            return updated value to node->data*/

        node->data = reverse(node->data);

        /*  updating node pointer so as to get
            next value */

        node = node->next;
    }
}

// Function to print nodes in linked list
void printList(struct Node* node)
{
    while (node != NULL) {
        printf("%d ", node->data);
        node = node->next;
    }
}

// Driver program to test above functions
int main()
{
    struct Node* head = NULL;
    head = newNode(56);
    head->next = newNode(87);
    head->next->next = newNode(12);
    head->next->next->next = newNode(49);
    head->next->next->next->next = newNode(35);

    printf(
        "\nList before reversing individual data item \n");
    printList(head);

    reverseIndividualData(head);

    printf("\nList after reversing individual data item\n");
    printList(head);

    return 0;
}

Output

List before reversing individual data item 
56 87 12 49 35 
List after reversing individual data item
65 78 21 94 53