如何在另一个结构中使用结构的 function？

Question

i'm doing a simple project in C in which, for the moment, i use two structs: Player and Card. I have created the 2 struct in different header files, because functions in Player use Card, but also other elements that I haven't already done. When I try to use getId() in Player, the VSCode's compiler says:

reference to external symbol _getId not resolved in _discardCard()

card.h code is:

#include <stdbool.h> 
typedef struct card{
    int id;
    bool black;
    int numElems;
    char* text[3];
}card;

card* initCard(int id,bool black,char* text[],int numElems)
int getId(card* c);

card.c code is:

#include "carta.h"
#include<stdio.h>
#include <stdbool.h>
#include <stdlib.h>

...
int getId(carta* c){
    return c->id;
}

Instead the code for Player.h is:

#include "card.h"
#define CARDSMAX 5

typedef struct{
    bool master;
    int id;
    int points;
    char* nickname;
    card* cards[CARDSMAX];
    int NumCards;
}player;

... //other functions

card* discardCard(int id,player* g);

The code for Player.c is:

#include "player.h"
#include <stdio.h>
#include <stdlib.h>
player* initPlayer(char* nickname,int id){
    player* g=(player*) malloc(sizeof (player));
    g->id=id;
    g->nickname=nickname;
    g->master=false;
    g->points=0;
    g->NumCards=0;
    for(int i=0;i<CARDSMAX;i++){
        g->cards[i]=(card*)malloc(sizeof(card));
    }
    return g;
}

....   

card* DiscardCard(int id,player* g){
    for(int i=0;i<CARDSMAX;i++){
        card* c=g->cards[i];
        if(getId(c)==id){
            card* e= g->cards[i];
            g->cards[i]=NULL;
            g->NumCards--;
            return e;
        }
    }
    return NULL;
}

Can someone help me? (If you see some inconsistency in the code, it'is because i tried a fast translation from my language)

Answer 1

So, as suggested, the problem was that in Windows' compiler, when you use struct that use function defined in other structs,it is required to pass the.obj file during the compilation. For doing this you need to compile every.c file that is used by others singulary and then link the.obj file created in this fase. So in my case the first step is to compile:

cl card.c

that create a card.obj (the Windows' compiler could show you a message that says something like:"The start point is not indicated" if you don't use a main in this first file, don't worry and carry on with this procedure) and then I compile:

cl player.c /link card.obj

So in this way you pass the compiled object in which it's provided the implementation of all the function in the struct.