Hi ! And oh I forgot in the last mail. The iterator is 'valid' if the contents of the container doesn't change, means there is no deletion, or addition in the container.
If there is addition / deletion the iterator gets invalidated. Indika Bandara Udagedara wrote: > > Hi, > can you explain the life cycle of an iterator ? > > pls consider following example. > > typedef map<int, int> mapii; > typedef map<int, int>::iterator itii; > > mapii m; > pair<itii, bool> p = m.insert(make_pair(1, 2)); > itii it = p.first; > > // do all sorts of insert/erase to map > // but dont remove pair(1,2) > m.insert(0, 1); > m.insert(2, 3); > m.insert(3, 4); > // so the map would be > // 0,1 > // 1,2 <-- we are looking at here > // 2,3 > // 3,4 > > // do some erases > m.erase(2); > m.erase(0); > // so the map would be > // 1,2 <-- we are looking at here > // 3,4 > > // do some inserts > m.insert(-1, 0); > m.insert(0, 1); > m.insert(5, 6); > // so the map would be > // -1,0 > // 0,1 > // 1,2 <-- we are looking at here > // 3,4 > // 5,6 > > // now we are going to remove 'it' which we kept safely > m.erase(it); > // so the map would be > // -1,0 > // 0,1 > // 3,4 > // 5,6 > > this works as expected. but can this be guarenteed. > eg. if i do all sorts of manipulations for the map without touching > the iterator would it last ? > > one more thing. the iterator is a local variable. map returns an > iterator on insert (not a reference to an iterator). so is what i'm > doing correct? can the iterator be treated like a pointer. i tried > with moving the local iterator around functions eg. returning > iterator. it works like a pointer as i understood. > > thanks. > >
