How to make global 2D array using vectors

Lost User

I am trying to make a global 2D array using vectors, but I am having some trouble in doing so. Below code is a small part of my project where I need to make a global 2D array whose size has to be passed through a command line. I am passing row and column as command line arguments. "ESSolver.h"

#include

using namespace std;

extern int row;
extern int col;

extern vector> _muPop(row, vector(col));

class ESSolver
{
public:
ESSolver();
void Init();
void Disp();

private:
	vector< vector > \*muPop;

};

"ESSolver.cpp"

#include
#include
#include "../include/ESSolver.h"

using namespace std;

ESSolver::ESSolver()
{
muPop = &_muPop;

return;

}

void ESSolver::Init()
{
// Initializing object variable
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
(*muPop)[i][j] = i+1;
}
}
}

void ESSolver::Disp()
{
// Initializing object variable
for (int i = 0; i < row; i++)
{
for (int j = 0; j < col; j++)
{
cout << (*muPop)[i][j] << " ";
}
cout << endl;
}
}

"main.cpp"

#include "../include/ESSolver.h"
#include #include using namespace std;

int row;
int col;

vector> _muPop(row, vector(col));

int main(int argc, char *argv[]){
//./main #row #col

row = atoi(argv\[1\]);
col = atoi(argv\[2\]);

ESSolver es;
es.Init();

}

Lost User

You declare your vector as a global, but the values of row and col will be zero when it is created. Make it a local variable and let your ESSolver object manage it. Or better still make it a member of the ESSolver class.

Jochen Arndt

Your concept is totally wrong and won't work at least here:

vector> _muPop(row, vector(col));

because row and col are not defined. Write a class that holds the 2D array. That class should have an initialisation function with the number of rows and columns as parameters that allocates the array and initialises the array items. Then there is even no need to have a global instance of that class. It can be a local member of your main function. You might also check if the usage of vector is really necessary. If you don't need vector specific operations using classic C style arrays or C++ array templates might be a better option.

CPallini

As suggested, don't use globals. Try, for instance

#include #include #include #include using namespace std;

class Matrix
{
int R, C;
vector > m;
public:
Matrix(int r, int c):R(r),C(c)
{
for (int r = 0; r());
for (int c = 0; c= 3)
{
rows = stoi(argv[1]);
cols = stoi(argv[2]);
}

Matrix m(rows,cols);
cout << m << endl;
}

Lost User

Thanks

CPallini

You are welcome.