Question

I need to get an input N from the user and generate a N*N matrix. How can I declare the matrix? Generally, the size of the array and matrix should be fixed at the declaration, right?
What about vector<vector<int>> ? I never use this before so I need suggestion from veteran.

Answer 1

Boost implements matrices (supporting mathematical operations) in its uBLAS library, and provides usage syntax like the following.

#include <boost/numeric/ublas/matrix.hpp>

int main(int argc, char* argv[])
{
    unsigned int N = atoi(argv[1]);
    boost::matrix<int> myMatrix(N, N);

    for (unsigned i = 0; i < myMatrix.size1 (); ++i)
        for (unsigned j = 0; j < myMatrix.size2 (); ++j)
            myMatrix(i, j) = 3 * i + j;

    return 0;
}