linkedlist - beras

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

struct beras{
    char tipeBeras[10];
    int stok;
    struct beras *next;
};

struct beras *head = NULL;

void clearbuffer();
void menu(struct beras *);
struct beras *insertKeAwal(struct beras *);
struct beras *hapusAwal(struct beras *);
int cekTipe(const char tipeBeras[]);

int main() {
    int pilihanMenu;

    do{
        system("clear");
        menu(head);
        printf("masukkan pilihan : ");
        scanf("%d", &pilihanMenu); clearbuffer();
        if (pilihanMenu == 1)
            head = insertKeAwal(head);
        if (pilihanMenu == 2)
            head = hapusAwal(head);
    }while (pilihanMenu != 3);

    return 0;
}

void clearbuffer(){
    char ch;
    while ((ch = getchar()) != '\n' && ch != EOF);
}

void menu(struct beras *head){
    printf("blue rice stock\n");
    printf("rice stock <STACK>\n\n");

    struct beras *ptr;
    ptr = head;

    while (ptr != NULL){

        if (ptr == head)
            printf("[%s grain] : %d kg(s) -> [top]\n", ptr->tipeBeras, ptr->stok);
        else
            printf("[%s grain] : %d kg(s)\n", ptr->tipeBeras, ptr->stok);

        ptr = ptr->next;
    }

    printf("\noption : \n");
    printf("1. Stok Beras\n");
    printf("2. Jual Beras\n");
    printf("3. keluar\n\n");
}

struct beras *insertKeAwal(struct beras *head) {
    struct beras *berasBaru; //inisialisasi tempat buat menyimpat data beras
    char tipeBeras[10];
    int stok;
    int cek;

    do {
        printf("masukkan tipe beras[short/medium/long] : ");
        scanf("%s", tipeBeras); clearbuffer();
        cek = cekTipe(tipeBeras);
    }while (cek == 0);

    do {
        printf("masukkan stok [10-100] kg : ");
        scanf("%d", &stok); clearbuffer();
    } while (stok < 10 || stok > 100);

    berasBaru = (struct beras *) malloc(sizeof(struct beras)); //alokasikan memory
    strcpy(berasBaru->tipeBeras, tipeBeras); //masukkan nilai
    berasBaru->stok = stok; //masukkan nilai

    /*   beras baru
     *   ---------------
     *   |        |    |
     *   |  data  |    |
     *   |        |    |
     *   ---------------
     */

    if (head == NULL){
        berasBaru->next = NULL; //set pointer next jadi null karena ini adalah node terakhir
        head = berasBaru;

        /*              beras baru
         *           ---------------
         *           |        |    |
         *   head -> |  data  | X  |
         *           |        |    |
         *           ---------------
         */

    } else {
        berasBaru->next = head;
        head = berasBaru;


        /*                              head
         *                               |
         *               beras baru      V beras lama1      beras lama2
         *           ---------------  ----------------   ------------------
         *           |        |    |  |         |    |   |          |     |
         *           |  data  |    |  |   data  |  ----->|   data   |  X  |
         *           |        |    |  |         |    |   |          |     |
         *           ---------------  ----------------   ------------------
         */


        /*                              head
         *                               |
         *               beras baru      V beras lama1      beras lama2
         *           ---------------  ----------------   ------------------
         *           |        |    |  |         |    |   |          |     |
         *           |  data  |  ---->|   data  |  ----->|   data   |  X  |
         *           |        |    |  |         |    |   |          |     |
         *           ---------------  ----------------   ------------------
         */


        /*              beras baru      beras lama1          beras lama2
         *           ---------------  ----------------   ------------------
         *           |        |    |  |         |    |   |          |     |
         *   head -> |  data  |  ---->|   data  |  ----->|   data   |  X  |
         *           |        |    |  |         |    |   |          |     |
         *           ---------------  ----------------   ------------------
         */
    }

    printf("sukses menambah beras...."); clearbuffer();
    return head;
}

struct beras *hapusAwal(struct beras *head){
    struct beras *temp;
    temp = head;

    /*              beras baru      beras lama1          beras lama2
     *           ---------------  ----------------   ------------------
     *           |        |    |  |         |    |   |          |     |
     *   temp -> |  data  |  ---->|   data  |  ----->|   data   |  X  |
     *   head -> |        |    |  |         |    |   |          |     |
     *           ---------------  ----------------   ------------------
     */


    if (temp == NULL){
        printf("\ntidak ada data...");
        clearbuffer();
    } else {
        head = head->next;
        free(temp);
        printf("sukses menjual beras...."); clearbuffer();
        /*              beras baru      beras lama1          beras lama2
         *           ---------------  ----------------   ------------------
         *           |        |    |  |         |    |   |          |     |
         *   temp -> |  data  |  ---->|   data  |  ----->|   data   |  X  |
         *   head -> |        |    |  |         |    |   |          |     |
         *           ---------------  ----------------   ------------------
         */

        /*                              head
         *                               |
         *               beras baru      V   beras lama1          beras lama2
         *           ---------------  ----------------   ------------------
         *           |        |    |  |         |    |   |          |     |
         *   temp -> |  data  |  ---->|   data  |  ----->|   data   |  X  |
         *           |        |    |  |         |    |   |          |     |
         *           ---------------  ----------------   ------------------
         */

        /*    head
         *    |
         *    V   beras lama1      beras lama2
         *   ----------------   ------------------
         *   |         |    |   |          |     |
         *   |   data  |  ----->|   data   |  X  |
         *   |         |    |   |          |     |
         *   ----------------   ------------------
         */
    }

    return head;
}


int cekTipe(const char tipeBeras[]){
    if (strcmp(tipeBeras, "long") == 0)
        return 1;
    if (strcmp(tipeBeras, "medium") == 0)
        return 1;
    if (strcmp(tipeBeras, "short") == 0)
        return 1;

    return 0;
}