CODEWITHSUNDEEP
c++seterase
cheng
cheng

Reputation: 2136

Will the erase function of set in C++ change the address of other elements?

I have the following code:

set<Key> test;
test.insert(key1);
test.insert(key2);
iter1 = test.find(key1);
iter2 = test.find(key2);
test.erase(iter1);

My question is, if key1 is deleted, now can I use iter2 to refer to key2 in test?

Thanks

Upvotes: 5

Views: 271

Answers (3)

Kerrek SB
Kerrek SB

Reputation: 477150

Strictly speaking you have to check the return value of the "insert" operation and ensure that key1 and key2 don't compare equal; otherwise iter1 == iter2 and erasing iter1 invalidates iter2. But in general see the previous answer, erasing an iterator invalidates only that iterator and no others.

Example:

struct Foo
{
  Foo(std::string s = "") : s(s) { }
  bool operator<(const Foo & other) { return s.size() < other.size(); }
}

std::set<Foo> x;
x.insert(Foo("Cat"));
x.insert(Foo("Dog")); // booboo

Upvotes: 3

lccarrasco
lccarrasco

Reputation: 2051

Asociative containers set, multiset, map and multimap are required to only invalidate iterators and references to the erased elements.

In a deque all the iterators and references are invalidated, unless the erased members are at an end (front or back) of the deque (23.2.1.3/4), in a list only the iterators and references to the erased element is invalidated (23.2.2.3/3) and on a vector every iterator and reference after the point of erase is invalidated (23.2.4.3/3)

Upvotes: 3

Cat Plus Plus
Cat Plus Plus

Reputation: 129814

Yes, set's erase invalidates only iterators that point to the element that was erased (note that this is not necessarily true for all containers).

Upvotes: 7

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