c how to make a dynamic array pointer in a struct

Question

I am taking in input from the user for the number of elemenets inside an array. The array is inside my struct 'Polymer'

struct Polymer
{
    int length;

    struct Monomer *monomer;

}polymer;

In main, I am creating a new monomer array pointer and setting the mononomer pointer in "Polymer" to it

struct Monomer *monomers[size];
polymer.monomer = momomers;

I am getting the error "Assignment from incompatible pointer type" which I assume is because we are converting a monomer array pointer to a monomer. How do I declare it as a monomer array pointer in the struct?

Answer 1

You are declaring an array of monomer pointers when you probably want an array of monomers . Drop the * :

struct Monomer monomers[size];
polymer.monomer = momomers;

Answer 2

struct Monomer *monomers[size];
polymer.monomer = momomers;

monomers is an array of pointers . They aren't pointing to any valid locations and has garbage values. While Polymer::monomer is a pointer . Array of pointers isn't type compatible to just a pointer.

Instead try -

struct Monomer monomers[size];
polymer.monomer = momomers;  // 2

Now this statement 2 is valid because array decays to a pointer.