How do i get access to an element in a set ?
vector<int> myvec (4,100);
int first = myvec.at(0);
set<int> myset;
myset.insert(100);
int setint = ????
Can anybody help ?
views:
61answers:
3
+4
A:
set<int>::iterator iter = myset.find(100);
if (iter != myset.end())
{
int setint = *iter;
}
Kristo
2010-03-29 20:18:06
You should check `iter!=myset.end()` before dereferencing that iterator.
Space_C0wb0y
2010-03-29 20:19:10
if you know you're looking for 100, why not just assign 100 to `setint`?
wilhelmtell
2010-03-29 20:19:30
The equivalent to that in the `vector` case is `vecint = *find(myvec.begin(), myvec.end(), 100);`
wilhelmtell
2010-03-29 20:21:13
+2
A:
You can't access set elements by index. You have to access the elements using an iterator.
set<int> myset;
myset.insert(100);
int setint = *myset.begin();
If the element you want is not the first one then advance the iterator to that element. You can look in a set to see if an element exists, using set<>::find(), or you can iterate over the set to see what elements are there.
wilhelmtell
2010-03-29 20:18:36
The iterators and positions of elements are invalidated only if you erase items from the set.
UncleBens
2010-03-29 20:39:23
Ah, sorry. inserting into a set doesn't invalidate old iterators, and erasing elements doesn't invalidate old iterators either (except of course for iterators pointing at the element removed).
wilhelmtell
2010-03-29 20:51:47
+1
A:
In general I find that this is a good documentation of the STL.
Space_C0wb0y
2010-03-29 20:20:20