CODEWITHSUNDEEP
carrayspointersstruct
Arndt Bieberstein
Arndt Bieberstein

Reputation: 1128

Array assignment with struct pointers in C

I need to hold a dynamic array of structs.

The types are defined like this. I'm not able to change those, because they are given by a library called flint (library for fast number theory).

typedef struct
{
    mp_ptr coeffs;
    slong alloc;
    slong length;
    nmod_t mod;
} nmod_poly_struct;

typedef nmod_poly_struct nmod_poly_t[1];

and my struct is defined like this:

typedef struct {
    mp_limb_t D;
    mp_limb_t length;
    nmod_poly_t *s;
} she_key_symmetric_t;

So my problem is to hold a set of nmod_poly_t objects. I initialize them and want so store them in the array.

nmod_poly_t poly;
nmod_poly_init(poly);

she_key_symmetric_t key;
// init and stuff
key.s[0] = poly; // This line does not work, because 
// it always says "array type 'nmod_poly_t' (aka 
// 'nmod_poly_struct[1]') is not assignable"

In the next step I have to get the values back out of the array

she_key_symmetric_t key;
// fully initialized key
nmod_poly_t poly = key.s[0];

So how do I need to declare my dynamic array s to store my strucs inside it?

Thanks in advance

Upvotes: 1

Views: 115

Answers (1)

Dabo
Dabo

Reputation: 2373

Following will work, assuming memory allocated properly for key.s and initialized 

nmod_poly_t poly; 
poly[0] =key.s[0][0];

Upvotes: 1

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