Reverse a Linked List in C with Explanation

C Program to Reverse a Linked List

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

struct node {
    int data;
    struct node *next;
};

struct node *head = NULL;

struct node *createNode() {
    struct node *newNode = (struct node *)malloc(sizeof(struct node));
    return newNode;
}

void insertNode() {
    struct node *temp, *ptr;
    temp = createNode();
    printf("Enter the data you want to insert: ");
    scanf("%d", &temp->data);
    temp->next = NULL;
    if (head == NULL)
        head = temp;
    else {
        ptr = head;
        while (ptr->next != NULL) {
            ptr = ptr->next;
        }
        ptr->next = temp;
    }
}

void listReverse() {
    struct node *prev = NULL, *current, *nextNode;
    current = head;
    while (current != NULL) {
        nextNode = current->next;
        current->next = prev;
        prev = current;
        current = nextNode;
    }
    head = prev;
    printf("List reversed successfully\n");
}

void viewList() {
    struct node *temp = head;
    if (temp == NULL) {
        printf("List is empty\n");
    } else {
        printf("List items are: \n");
        while (temp != NULL) {
            printf("%d\t", temp->data);
            temp = temp->next;
        }
        printf("\n");
    }
}

int menu() {
    int choice;
    printf("\n 1. Add value to the list");
    printf("\n 2. Reverse the list");
    printf("\n 3. View the list");
    printf("\n 4. Exit");
    printf("\n Please enter your choice: ");
    scanf("%d", &choice);
    return choice;
}

int main() {
    while (1) {
        switch (menu()) {
            case 1:
                insertNode();
                break;
            case 2:
                listReverse();
                break;
            case 3:
                viewList();
                break;
            case 4:
                exit(0);
            default:
                printf("Invalid choice\n");
        }
    }
    
    return 0;
}

Output:

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