Thread: Problem Understanding this

Post the relevant code.
How you allocate 2-D array.
Pass to function. how it is used in function.

matrix[5][5] and *(*(matriz+5)+5) are the same.

He says to me that I cannot use matriz[5][5] because that doesn't exist.

BTW, the allocation:

Code:

float **criacao_tdd (int pola, int *c) //tdd[c][c+1] c= numero de pontos
{
    float **tdd;
    int   n;
    char op;

    do{
        system("cls");
        printf("\t\t\tCriacao da Tabela Das Diferencas Divididas \n\nQuantos pontos se utilizara na tabela? \n(Numero de pontos máximos: %d)", pola);
        scanf("%d", c);
        if(*c>1 && *c <= pola)
            do{
                printf("\nDeseja Alterar o valor introduzido? S/N");
                op = toupper(getch());
            }while(op != 'S' && op != 'N');
    }while(*c<=1 || *c>pola || op == 'S');

    tdd = (float **) calloc (*c, sizeof(float *));


    for ( n = 0; n < *c; n++ )
    {
        tdd[n] = (float*) calloc (*c+1, sizeof(float));

        if (tdd[n] == NULL)
            break;
    }

    if(tdd == NULL || tdd[n] == NULL)
    {
        do{
            printf("\nErro: não há memória \nDeseja introduzir um novo valor? (S/N) \n\n");
            op = toupper(getch());
        }while(op != 'S' && op != 'N');

        if (op == 'N')
            exit(1);
        else
            tdd=criacao_tdd(pola, c);
    }

    return (tdd);
}

EDIT: When I call the function that allocates this, I do this: tdd = criacao_tdd(pola, c);


One function that use it:

Code:

int px (int c, float tdd[][c+1], float x)
{
    int coluna = 1, linha = 0, op_erro, aux = 0;
    float px = 0, aux_calculo;
    char op;

    do{
        system("cls");
        printf("Deseja Calcular o Erro? ");
        op = toupper(getch());

        if (op == 'S')
            op_erro = 1;
        if (op == 'N')
            op_erro = 0;

    }while(op_erro != 1 && op_erro != 0);

    for(coluna = 1; coluna < c+1-op_erro; coluna++)
    {
        aux_calculo = tdd[0][coluna];

        for(linha = 0; linha < aux; linha++)
            aux_calculo = aux_calculo*(x-tdd[linha][0]);

        aux++;
        px = px+aux_calculo;
    }

    printf("\n\nX = %f ",px);
    return op_erro;
}

Then you can merilly go tell your teacher that he/she is wrong.
Both of these syntaxes are valid:
aux_calculo = tdd[0][coluna];
aux_calculo = *(*(tdd+0)+coluna);
The former is better because it's more readable.