Create a function to allocate a dynamic matrix

Question

I want to create a function in C that allocates a dynamic matrix; the idea is to allocate an array whose elements are pointers to arrays; if I want to do that in a function, what is the correct code?

this

f(***matrix)

or this

f(**matrix)?

I would say the first one, but I'm not sure. thank you!

Answer 1

You probably want something like

double **
allocate_array(size_t rows, size_t cols)
{
    double **array = malloc(cols * sizeof(*array));
    if (array == NULL) return NULL;
    for (size_t i = 0; i < cols; i++) {
        array[i] = malloc(rows * sizeof(*array[i]));
        for (size_t j = 0; j < rows; j++) array[i] = 0.0;
        if (array[i] == NULL) {
             while (i != 0) free(array[--i]);
             free(array);
             return NULL;
        }
    }
    return array;
}