Vector of Vectors to create matrix


I am trying to take in an input for the dimensions of a 2D matrix. And then use user input to fill in this matrix. The way I tried doing this is via vectors (vectors of vectors). But I have encountered some errors whenever I try to read in data and append it to the matrix.

//cin>>CC; cin>>RR; already done
vector<vector<int> > matrix;
for(int i = 0; i<RR; i++)
{
    for(int j = 0; j<CC; j++)
    {
    cout<<"Enter the number for Matrix 1";
         cin>>matrix[i][j];
    }
}

Whenever I try to do this, it gives me a subscript out of range error. Any advice?


Answers:


As it is, both dimensions of your vector are 0.

Instead, initialize the vector as this:

vector<vector<int> > matrix(RR);
for ( int i = 0 ; i < RR ; i++ )
   matrix[i].resize(CC);

This will give you a matrix of dimensions RR * CC with all elements set to 0.