What is the right way to initialize double pointer in c

As title, I want to know how to initialize double pointer with sizeof a pointer.

For instance

int **p=malloc(sizeof *p * rows);

for(size_t i = 0; i < rows; i++){
    p[i]=malloc(sizeof ? * cols);
}

What should I fill in ?.

Any help would be appreciated.

>Solution :

It looks like you want p to be an array that can hold pointers, and the number of pointers is rows. So you can allocate memory for p like this:

int ** p = malloc(sizeof(int *) * rows);

Now if you want p[i] to point to an array that holds cols ints, do this:

p[i] = malloc(sizeof(int) * cols);