displaying 2-d vector

[shotjase]

void display(vector < vector <bool> > g, int rows, int cols)
{
// pre : none
// post : displays the grid

for (int rows = 0; rows < 9; rows++)
{
for (int cols = 0; cols < 30; cols++)
cout << g.at(rows).at(cols)
cout << endl;
}
}

is this right?? if not wat needs changing??
thanks

[jsmith]

First, your declaration of "rows" and "cols" as for loop indices shadows the parameters of the same name.

Second, I would strongly recommend passing the matrix by const reference to the function, as the overhead of copying the whole thing onto the stack when the function is called is significant.

void display( vector< vector<bool> > const& g, int rows, int cols ) {
    for( int r = 0; r < rows; ++r )
        for( int c = 0; c < cols; ++c )
            cout << g.at( r ).at( c ) << endl;
}