linked.c

#include <stdio.h>
#include <cs50.h>

void quit();
void show_menu();

void print_list();
void insert_at_tail();
int search();

int running = 1;

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

node *head;

int main()
{
    
    while(running)
    {
        show_menu();
        int input = get_int();
        
        if (input==0)
        {
            quit();
        }
        else if(input==1)
        {
            print_list();
        }
        else if(input==2)
        {
            printf("What value to insert: ");
            int val = get_int();
            insert_at_tail(val);
        }
        else if(input==3)
        {
            printf("What value would you like to find: ");
            int val = get_int();
            if(search(val))
            {
                printf("Found it!\n");
            }
            else
            {
                printf("Did not find it!\n");
            }
        }
    }
}

void quit()
{
    running = 0;
    printf("Bye, thanks for playing.\n");
}

void show_menu()
{
    printf("1. Print list.\n");
    printf("2. Insert value at tail.\n");
    printf("3. Search for value.\n");
    printf("0. Quit to command line.\n");
}

void print_list()
{
    if(head==NULL)
    {
        printf("List empty. No elements.\n");
    }
    else
    {
        node* crawler = head;
        
        while (crawler->next != NULL)
        {
            printf("Value is: %d\n", crawler->val);
            crawler = crawler -> next;
        };
        if (crawler->next == NULL)
        {
            printf("Value is: %d\n", crawler->val);
        }
        printf("Finished with the list.\n");
    }
}

void insert_at_tail(int passed_val)
{
    if(head==NULL) // list is empty, set head to this value.
    {
        head = malloc(sizeof(node));
        head->val = passed_val;
        head->next = NULL;
    }
    else
    {
        node* crawler = head;
        
        while(crawler->next != NULL)
        {
            crawler = crawler -> next;
        }
        node * last = malloc(sizeof(node));
        crawler->next = last;
        last->val = passed_val;
        last -> next = NULL;
    }
}

int search(int n)
{
    node* crawler = head;
    while(crawler->next != NULL)
    {
        if(crawler->val == n)
        {
            return 1;
        }
        crawler = crawler->next;
    }
    if(crawler->next == NULL)
    {
        if(crawler->val ==n)
        {
            return 1;
        }
    }
    return 0;
}