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Suppose I have two items, a and b, that compare the same. So a < b is false, and b < a is false. If these items are inserted into a std::multiset (or std::multimap) as keys, do I have any guarantees of their final sorted order?
I've checked a couple of references, but I couldn't find the answer. I'm tempted to think that there are no guarantees and that it's left up to each particular implementation.
Thanks.
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Following are the properties of multisets: Stores elements in sorted order. It allows the storage of multiple elements. We can erase more than 1 element by giving the start iterator and end iterator.
stable_sort() in C++ STL. stable_sort() is used to sort the elements in the range [first, last) in ascending order. It is like std::sort, but stable_sort() keeps the relative order of elements with equivalent values.
Note that this is the largest item in the multiset, because the multiset is always stored in sorted order.
In case of Set, data is stored in sorted order. In case of MultiSet also the data is stored in sorted order. In Set duplicate values are not allowed to get stored.
This thread implies that it is not guaranteed by the current standard but is met by all known current implementations, and gives a link to the C++0x draft standard that includes a guarantee.
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