linked.c

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

// November 7 2020
// Data Structure Fun
// Linked List Implementation

typedef struct node {
    int val;
    struct node* next;
} node;

void append_node(node**, int);
void append_node_end(node**, int);
void remove_node(node**, int);
void display_list(node*);

int main(void) {

    node* head = NULL;
    int inp, val;

    printf("\nSimple Linked List Implementation.\n");
    printf("Select An Action...\n\n");
    printf("1) Add to List\n");
    printf("2) Remove From List\n");
    printf("3) Display List\n\n");

    // add some random values to the list
    time_t t;
    srand((unsigned) time(&t));
    for (int i = 0; i < 10; i++) {
        append_node_end(&head, rand() % 100);
    }

    for (;;) { // menu loop

        printf("$ ");
        scanf("%d", &inp);

        switch (inp) {
            case 1:
                printf("What Value Would You Like To Add?\n");
                printf("> ");
                scanf("%d", &val);
                append_node_end(&head, val);
                break;
            case 2:
                printf("Which Item Would You Like To Remove?\n");
                printf("> ");
                scanf("%d", &val);
                remove_node(&head, val);
                break;
            case 3:
                display_list(head);
                break;
            default:
                printf("Unknown Option.\n");
                break;
        }

    }

}

void append_node(node** head, int val) {

    node* new = (node*)malloc(sizeof(node));
    new->val = val;
    new->next = NULL;

    if (*head == NULL) {
        *head = new;
        return;
    }

    new->next = *head;
    *head = new;

}

void append_node_end(node** head, int val) {

    node* new = (node*)malloc(sizeof(node));
    new->val = val;
    new->next = NULL;

    if (*head == NULL) {
        *head = new;
        return;
    }

    node* temp = *head;

    while (temp->next != NULL) {
        temp = temp->next;
    }

    temp->next = new;

}

void remove_node(node** head, int index) {

    node *temp = *head, *prev = *head;

    if (index == 0) {
        if (temp->next != NULL) {
            *head = temp->next;
            free(temp);
            return;
        } else {
            printf("Error: Can't Delete Entire List.\n");
            return;
        }
    }

    for (int i = 0; i < index; i++) {
        if (temp == NULL) {
            printf("Error: Index Out Of Bounds!\n");
            return;
        }
        prev = temp;
        temp = temp->next;
    }

    prev->next = temp->next;
    free(temp);

}

void display_list(node* head) {

    int counter = 0;

    while (head != NULL) {
        printf("Item #%d Has Value %d\n", counter, head->val);
        head = head->next;
        counter += 1;
    }

}