visual studio LNK2019

Question

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

#define CMAX 52
#define BUFF_SIZE 256

struct input
{
    int card[CMAX];
    int num;
};

int  comp(void);
int  getcard(struct input *inp_card);
void print_card(const struct input *inp_card, const char *card[]); 

int calc(const struct input *inp_card);

#define randmize() srand(time(NULL))

int main()
{
    const static char* card[] = { "0","A","2","3","4","5","6","7","8","9","10","J","Q","K" };

    int x;
    int c_score;
    int h_score;
    char in[BUFF_SIZE];
    struct input h_card = {{0}, 0};

    printf("Blackjack Game \n");
    randmize();
    c_score = comp();

    x = getcard( &h_card);
    printf("you took the '%s'",card[x] );
    printf("get a card (y/n)");

    while (h_card.num < CMAX && fgets(in, BUFF_SIZE, stdin) != NULL)
    {
        if (strncmp(in, "y", 1) == 0)
        {
            x = getcard( &h_card);
            printf("you took the '%s'", card[x]);
            print_card(&h_card, card);
            printf("get a card (y/n)");
        }
        else if
            (strncmp(in, "n", 1) == 0)
            break;
        else
            printf("type y or n.\n");
    }

    h_score = calc(&h_card);
    printf("your score : %d\ncomputer score : %d\n", h_score, c_score);

    if
        (c_score <= 21 && (h_score > 21 || c_score > h_score))
        printf("Computer WIN!\n");
    else if
        (h_score <= 21 && (c_score > 21 || h_score > c_score))
        printf("You WIN!\n");
    else
        printf("Draw\n");

    return 0;
}

right now I am trying to make a blackjack game with C in VisualStudio.

but it makes errors and i dont know why

how should i change my code?

it said error code LNK1120 and LNK2019,getcardmain,calcmain,compmain,print_cardmain

i think i have to fix getcard, print_card and calc

but i dont know how