How can I resize a 2D C++ vector?

Question

I have a 2D char vector:

vector< vector > matrix;

I will read in a matrix as an input and store it in that v

Answer 1

    const size_t ROW = 10;
    const size_t COL = 20;
    std::vector> v;

    v.resize( ROW );

    std::for_each( v.begin(), v.end(), 
                   std::bind2nd( std::mem_fun_ref( &std::vector::resize ), COL ) );

    std::cout << "size = " << v.size() << std::endl;
    for ( const std::vector &v1 : v ) std::cout << v1.size() << ' ';
    std::cout << std::endl;