Multi-dimensional vector

Question

How can I create a 2D vector? I know that in 2D array, I can express it like:

a[0][1]=98;
a[0][2]=95;
a[0][3]=99;
a[0][4]=910;

a[1][0]=98;
a[1][1]=989;
a[1]         


        

Answer 1

std::vector< std::vector > a;

    //m * n is the size of the matrix

    int m = 2, n = 4;
    //Grow rows by m
    a.resize(m);
    for(int i = 0 ; i < m ; ++i)
    {
        //Grow Columns by n
        a[i].resize(n);
    }
    //Now you have matrix m*n with default values

    //you can use the Matrix, now
    a[1][0]=98;
    a[1][1]=989;
    a[1][2]=981;
    a[1][3]=987;

//OR
for(i = 0 ; i < m ; ++i)
{
    for(int j = 0 ; j < n ; ++j)
    {      //modify matrix
        int x = a[i][j];
    }

}