Question

I have a unit test program i wrote to catch errors in the functions of an open source project before the initial compilation. All of the functions i need to test return a pointer to a struct(in this case bn_poly) while my variable is NOT a pointer. I know there must be an easier solution to this problem but after a bit of googling i came up with nothing, here is what i’m currently doing

/* only relevant part of code */
struct *bn_poly poly_summ;
unsigned i
poly_summ = (struct bn_poly*)bu_malloc(sizeof(struct bn_poly),"sum");
/* test multiplication and begin checking data */
*poly_summ = bn_poly_mul(&poly_summ,poly_eqn,poly_mul);
/* bn_poly returns a pointer to bn_poly, so i have to declare
 * a temporary pointer to find the value. Is this the only way
 * or is there a type cast method i am missing?
 */

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what i would like to be able to do:

struct bn_poly poly_summ;
poly_summ = (somethingToConvertReturnVal)bn_poly_mul(&poly_summ,poly_eqn,poly_mul);
/* no memory allocation needed! */

Answer 1

I’m a little bit confused regarding what your question is But here’s what i know about “casting” pointers.

• the & symbol is the reference symbol, so &x gives you the address of x, or a pointer which points to x

• the * symbol is the deference symbol, so suppose x is a pointer, *x gives you the value x points to

in your case, i think you want

struct bn_poly poly_summ;
poly_summ = *(bn_poly_mul(/*params*/));

as an additional note, by the looks of it, bn_poly_mul looks like it already allocates your struct and puts it on the heap. You don’t even need to allocate it, in-fact doing so would result in a memory leak

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Also, the fact that the first parameter of bn_poly_mul is &poly_summ is a little bit off-putting to me, so I’d have to see the function to know for sure