What does this pointer to pointer in a struct mean?

Question

So I was given a struct:

struct Xxx
{
    struct Yyy{...};
    Yyy **yyys;             // matrix of yyys
};

I am confused about how pointer to pointer is related to a matrix?

And how can I initialize a new Yyy and a new Xxx?

Answer 1

The first level pointer would point to an array of pointers, and each second level pointer would point to an array of Yyy.

They can be set up as follows:

struct Yyy **makeMatrix(int rows, int cols)
{
    int i;
    struct Yyy **result = malloc(rows*sizeof(struct Yyy *));
    for (i = 0; i < rows; i++) {
        result[i] = malloc(cols*sizeof(struct Yyy));
    }
    return result;
}