C++ accessing class array pointer in a pointer to a structure - c++

Question

I am new to C++ and I really need some help on this. I am trying to create a structure to interface with the GSL Monte-Carlo algorithms (a fact that is really not important for this example). I have searched all of the C++ tutorials, the stackoverflow posts and the GSL documentation with no luck. I am using the armadillo package for matrix manipulation; it is very robust. I am unable to use a dynamic array within the structure, as per the documentation, so I am trying to find a way to make my structure variable *M point to the values in my array *L[]. I am sure that this would be better with a vector but 1) the rest of the code (in bad form) uses pointers already, and 2) I am looking at this as a learning experience. I am surprised that the addresses for *M and *L[] are not the same in my code. I am also, less importantly, surprised that my std::cout prints a different number of spaces for each line. The code exits before printing the last std::cout as shown in the output below.
Thanks for your help!
#include "pch.h"
#include "stdio.h"
#include "complex"
#include "new"
#include "armadillo"
using namespace arma;
class Link
{
public:
arma::Mat<cx_double>::fixed<3, 3>* dir[4]; // pointer to directional SU(3) matrices
Link(); // default constructor
};
Link::Link() // default constructor - all directional matrices are the identity
{
for (size_t hcount = 0; hcount < 4; hcount++)
{
dir[hcount] = new arma::Mat<cx_double>::fixed<3, 3>{ fill::eye }; // create directional matrix in direction hcount
}
}
struct Param
{
Link* M;
};
int main()
{
const int size = 10;
Param* Parameters = new Param{ NULL };
Link* L[size];
arma::Mat<cx_double>::fixed<3, 3> One{ fill::eye };
for (size_t hcount = 0; hcount < 10; hcount++)
{
L[hcount] = new Link();
*L[hcount]->dir[1] = *L[hcount]->dir[1] + hcount * One; // Make each array element #1 unique
}
Parameters->M = L[0];
std::cout << "&L = " << &L << std::endl;
std::cout << "&Parameters->M = " << &Parameters->M << std::endl; // surprised that addresses are not the same
std::cout << std::endl;
std::cout << "&L[0] = " << &L[0] << std::endl;
std::cout << "&Parameters->M[0] = " << &Parameters->M[0] << std::endl;
std::cout << std::endl;
std::cout << "&L[5] = " << &L[5] << std::endl;
std::cout << "&Parameters->M[5] = " << &Parameters->M[5] << std::endl;
std::cout << std::endl;
std::cout << "&L[5]->dir[1] = " << &L[5]->dir[1] << std::endl;
std::cout << "&Parameters->M[5].dir[1] = " << &Parameters->M[5].dir[1] << std::endl;
std::cout << std::endl;
std::cout << "*L[5]->dir[1] = " << *L[5]->dir[1] << std::endl; // This works
std::cout << "*Parameters->M[5].dir[1] = " << *Parameters->M[5].dir[1] << std::endl; // This does not
std::cout << std::endl;
}
OUTPUT
&L = 0024F7CC
&Parameters->M = 004EEFD8
&L[0] = 0024F7CC
&Parameters->M[0] = 004E0578
&L[5] = 0024F7E0
&Parameters->M[5] = 004E05C8
&L[5]->dir[1] = 004E50C4
&Parameters->M[5].dir[1] = 004E05CC
*L[5]->dir[1] = (+6.000e+00,+0.000e+00) (0,0) (0,0)
(0,0) (+6.000e+00,+0.000e+00) (0,0)
(0,0) (0,0) (+6.000e+00,+0.000e+00)
*Parameters->M[5].dir[1] =

Answer 1

&L is the adress of L, so it's the adress of the pointer to the first element not the adress of the first elemenr itself. Same for & Parameters->M. That is the adress of thd the Member M from Parameters. You want to compare L[0] with Parameters->M except when M should not point to the element that L[0] refers to but to the start of the array itself, then you want to compare it with L. But then you also have to change the assignment.
I find it a bit weird that you use an array of pointers. Just use an array of Links.