matrix in a class in C++ - c++

Question

the following code is for three classes , class One, class Two, class Three.
class Three takes tow vectors, the first vector contains instances of One , the second vector contains instances of Two.
I want to get a 2D matrix via a method in Three , this matrix will have two equal indices each one is the size of the vector of One instances.
I don't know where to declare this matrix , and how to initialize it.
i will present a code is working fine before i declare the matrix , then i will present one example of my many tries which is not working and producing error messages.
here is the code before declaring the matrix(it works fine)
#include<iostream>
#include<vector>
#include <stdlib.h>
using namespace std;
const unsigned int N = 5;
class One
{
private:
unsigned int id;
public:
unsigned int get_id(){return id;};
void set_id(unsigned int value) {id = value;};
One(unsigned int init_val = 0): id(init_val) {}; // constructor
~One() {}; // destructor
};
class Two
{
private:
One first_one;
One second_one;
unsigned int rank;
public:
unsigned int get_rank() {return rank;};
void set_rank(unsigned int value) {rank = value;};
unsigned int get_One_1(){return first_one.get_id();};
unsigned int get_One_2(){return second_one.get_id();};
Two(const One& One_1 = 0, const One& One_2 =0 , unsigned int init_rank = 0)
: first_one(One_1), second_one(One_2), rank(init_rank)
{
}
~Two() {} ; // destructor
};
class Three
{
private:
std::vector<One> ones;
std::vector<Two> twos;
public:
Three(vector<One>& one_vector, vector<Two>& two_vector)
: ones(one_vector), twos(two_vector)
{
}
~Three() {};
vector<One> get_ones(){return ones;};
vector<Two> get_twos(){return twos;};
void set_ones(vector<One> vector_1_value) {ones = vector_1_value;};
void set_twos(vector<Two> vector_2_value) {twos = vector_2_value;};
};
int main()
{
cout<< "Hello, This is a draft for classes"<< endl;
vector<One> elements(5);
cout<<elements[1].get_id()<<endl;
vector<Two> members(10);
cout<<members[8].get_One_1()<<endl;
Three item(elements, members);
cout<<item.get_ones()[3].get_id() << endl;
return 0;
}
now i declared a method to produce a matrix in Three , the method's name is get_Mat() here is the code :
#include<iostream>
#include<vector>
#include <stdlib.h>
using namespace std;
const unsigned int N = 5;
class One
{
private:
unsigned int id;
public:
unsigned int get_id(){return id;};
void set_id(unsigned int value) {id = value;};
One(unsigned int init_val = 0): id(init_val) {}; // constructor
~One() {}; // destructor
};
class Two
{
private:
One first_one;
One second_one;
unsigned int rank;
public:
unsigned int get_rank() {return rank;};
void set_rank(unsigned int value) {rank = value;};
unsigned int get_One_1(){return first_one.get_id();};
unsigned int get_One_2(){return second_one.get_id();};
Two(const One& One_1 = 0, const One& One_2 =0 , unsigned int init_rank = 0)
: first_one(One_1), second_one(One_2), rank(init_rank)
{
}
~Two() {} ; // destructor
};
class Three
{
private:
std::vector<One> ones;
std::vector<Two> twos;
public:
Three(vector<One>& one_vector, vector<Two>& two_vector)
: ones(one_vector), twos(two_vector)
{
}
~Three() {};
vector<One> get_ones(){return ones;};
vector<Two> get_twos(){return twos;};
void set_ones(vector<One> vector_1_value) {ones = vector_1_value;};
void set_twos(vector<Two> vector_2_value) {twos = vector_2_value;};
unsigned int get_Mat() {
unsigned int mat[ones.size()][ones.size()];
for(unsigned int i = 0; i < ones.size(); ++i)
for(unsigned int j = 0; j < ones.size(); ++j)
mat[i][j] = 1;
return mat;}
};
int main()
{
cout<< "Hello, This is a draft for classes"<< endl;
vector<One> elements(5);
cout<<elements[1].get_id()<<endl;
vector<Two> members(10);
cout<<members[8].get_One_1()<<endl;
Three item(elements, members);
cout<<item.get_ones()[3].get_id() << endl;
return 0;
}
I will be very thankful if you can help me to find a way to produce this matrix via a method in class Three.
Thanks.

Answer 1

get_Mat returns an integer, not a matrix. It is better to use vector<vector<unsigned int> >, that will avoid a lot of troubles later on.
Or have a look here (c++):
Return a 2d array from a function
or here (C):
Return a 2d array from a function