What do I want to do?

I want to make an array of struct types and insert struct instances into it.

{"struct Matrix matrix1", "struct Matrix matrix2"}

What have I done till now?

I have created a function create_struct() that takes the necessary parameters for the struct and return a struct pointer.

typedef struct
{
    size_t rows, columns;
    int *table;
} mat;

mat *create_struct(int x, int y)
{
    mat *data = (mat *)malloc(sizeof(*data));
    data->table = malloc(sizeof(int[(x * y)]));
    data->columns = y;
    data->rows = x;
    return data;
}

Then I created a pointer-to-object in this case struct and tried inserting struct instances with help of a for loop and the create_struct() function. But doing so the program crashes.

int main()
{
    size_t dimensions[2][2] = {{3, 3}, {3, 2}};

    mat *matrix;

    for (size_t i = 0; i < 2; i  )
    {
        matrix[i] = create_struct(dimensions[i][0], dimensions[i][1]);
    }

    return 0;
}

I think the main issue is with this line.

matrix[i] = create_struct(dimensions[i][0], dimensions[i][1]);

First of all, the above will result in to compile error a value of type "mat *" cannot be assigned to an entity of type "mat"

So to solve this I did something like this. Which I think is completely vague. I might be wrong.

matrix[i] = *create_struct(dimensions[i][0], dimensions[i][1]);

What do I expect from the answers

The following should be the main point of focus:

• Is it possible to do something like I'm doing?
• Is there a better way or procedure to insert struct instances into a struct types array?
• Provide information if you feel that I lack any conceptual knowledge.

CodePudding user response：

Of course. Just allocate the memory for pointers to mat rather than dereferencing uninitialized pointer matrix. Alternatively use an array of pointer to mat.

int main()
{
    size_t dimensions[2][2] = {{3, 3}, {3, 2}};

    mat** matrix = calloc(2, sizeof *matrix);
    // OR
    // mat* matrix[2];

    for (size_t i = 0; i < 2; i  )
    {
        matrix[i] = create_struct(dimensions[i][0], dimensions[i][1]);
    }

    return 0;
}