Problem when I try pass a struct pointer to a function

Question

Whats's wrong with this code?

typedef struct jogador{
    char nome[7];
    int pecas[6][2];
}Jogador;

void distribuir_pecas( Jogador* jogadores );

int main()
{
    Jogador* jogadores;
    jogadores = (Jogador*) malloc( 4 * sizeof(Jogador));
    distribuir_pecas( jogadores );
    return 0;
}
void distribuir_pecas( Jogador* jogadores ){
    int domino[28][2];
    int vetor_aux[28];

    int i, j;
    int peca_sorteada;
    int num_jogador = 0;
    int num_domino = 0;
    srand(time(NULL));

    for( i = 0; i < 28; i++){
        vetor_aux[i] = 1;
    }
    for( i = 0 ; i < 7; i++){
        for( j = 0; j < 7; j++){
            if( j == 0 ){
                j = i;
            }
            domino[num_domino][0] = i;
            domino[num_domino][1] = j;
            //printf("%d*%d\n", domino[num_domino][0], domino[num_domino][1]);
            num_domino++;
        }
    }

    while( num_jogador < 4 ){
        for( i = 0; i < 6; ){
            peca_sorteada = rand()%28;
            if( vetor_aux[peca_sorteada] ){

                vetor_aux[peca_sorteada] = 0;
                jogadores[num_jogador].pecas[i][0] = domino[peca_sorteada][0];
                jogadores[num_jogador].pecas[i][1] = domino[peca_sorteada][1];
                i++;
                printf("[%d|%d]\n",jogadores[num_jogador].pecas[i]                        [0],jogadores[num_jogador].pecas[i][1]);
            }
        }
        printf("\n\n");
        num_jogador++;
    }
}

When I try equate domino[peca_sorteada][0] to jogadores[num_jogador].pecas[i][0], for exemple, using a -> operand a compilation error ocurrs, but with . operand the printf don't print the correct value. Why????

Please clarify your question. Give an example of some code that doesn't work, and give the output it produces. Also, please simplify your code example (do we really need to see all these loops, and the mallocs, etc.?) — Oliver Charlesworth
– Oliver Charlesworth, Commented Nov 9, 2010 at 1:11

Cameron Skinner · Accepted Answer · 2010-11-09 01:07:08Z

3

Not sure if this is the underlying problem, but this:

int domino[28][2];
....
for( i = 0 ; i < 7; i++){
    for( j = 0; j < 7; j++){
        if( j == 0 ){
            j = i;
        }
        domino[num_domino][0] = i;
        domino[num_domino][1] = j;
        //printf("%d*%d\n", domino[num_domino][0], domino[num_domino][1]);
        num_domino++;
    }
}

is going to cause you problems. num_domino will be 49 by the end of this double loop, but the domino array is only 28 elements long.

answered Nov 9, 2010 at 1:07

Cameron Skinner

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2 Comments

Cameron Skinner Over a year ago

You do use it inside the loop, though. And you're writing to elements of domino that are outside its bounds.

adriano Over a year ago

It´s true Cameron. I'm increase 'i' before print the content of 'jogadores'.Thanks!

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