Question

I have a vector of Rect: vector<Rect> myRecVec;

I would like to remove the ones which are overlapping in the vector:

So I have 2 nested loop like this:

vector<Rect>::iterator iter1 = myRecVec.begin();
vector<Rect>::iterator iter2 = myRecVec.begin();

while( iter1 != myRecVec.end() ) {
    Rectangle r1 = *iter1;

    while( iter2 != myRecVec.end() ) {
        Rectangle r2 = *iter1;

        if (r1 != r2) { 
             if (r1.intersects(r2)) {
                 // remove r2 from myRectVec
             }
        }
    }
}

My question is how can I remove r2 from the myRectVect without screwing up both my iterators? Since I am iterating a vector and modifying the vector at the same time?
I have thought about putting r2 in a temp rectVect and then remove them from the rectVect later (after the iteration). But how can I skip the ones in this temp rectVect during iteration?

Answer 1

1. You need to increment iter1 and iter2.
2. erase returns an iterator to the next element. When you delete, use this instead of incrementing the iterator.

Like so:

while( iter1 != myRecVec.end() ) {
    Rectangle r1 = *iter1;

    iter2 = iter1 + 1;

    while( iter2 != myRecVec.end() ) {
        Rectangle r2 = *iter2;

        if( r1.intersects(r2) ) {
            iter2 = myRectVec.erase(iter2);
        }
        else {
            ++iter2;
        }
    ++iter1;
}