iterator for 2d vector

Question

How to create iterator/s for 2d vector (a vector of vectors)?

Answer 1

Assuming you mean an STL iterator, and a custom container that implements a generic 2D array of objects, this is impossible. STL iterators support only increment and decrement (i.e. "next" an "previous") operations, where motion through a 2D set requires four such primitives (e.g. left/right/up/down, etc...). The metaphors don't match.

What are you trying to do?

Answer 2

Although your question is not very clear, I'm going to assume you mean a 2D vector to mean a vector of vectors:

vector< vector<int> > vvi;

Then you need to use two iterators to traverse it, the first the iterator of the "rows", the second the iterators of the "columns" in that "row":

//assuming you have a "2D" vector vvi (vector of vector of int's)
vector< vector<int> >::iterator row;
vector<int>::iterator col;
for (row = vvi.begin(); row != vvi.end(); row++) {
    for (col = row->begin(); col != row->end(); col++) {
        // do stuff ...
    }
}