Stl invalidating iterators aries woman dating an aquarius man

That is the purpose of a map: access to storage of mutable data via some form of unique key.Lastly, maps are unique among all STL associative containers in that they do implement the [] operator. Oops, I knew I'd get flamed for my response because I realized last night while I was caulking my bathroom sink that you were trying to swap associated values, not keys, in which case the original problem could be solved using std::advance().

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Hope this will help Using a for loop to increment an iterator 100 times, doesn't sound fast.

Also just changing the iterator isn't what I want, I want direct access.

I'm surprised that STL uses a chain of blocks.

With the ring buffer approach, if your dequeue stays within a certain bound, you never need to allocate again once it gets up to size.

Another one is using 2 lists where one works as a key list.

Another solution is iterating through the keys a random number of times but creating a new iterator every step would be to slow.Other languages call it a "dictionary" or "associative array." There is no "index" order. do as adir suggests and iterate through the map, element by element, or 2. maps guarantee O(log N) lookups by storing elements in a tree in order.do as I suggest and know the keys for the elements you want. You can't just go and change elements willy-nilly in a map.If neither of these work, perhaps you are using the wrong data type. If you really need to do that, then map isn't the right container. Further, exchanging the pairs' seconds doesn't do anything to the map's internal storage.If you want to be able to do "iterator N" then you need a container that supports random access iterators. The order is only defined internally to be a linear, strict-weak, increasing ordered set. (Copy constructors work wonders.) It is not incongruous to modify a key's associated value.If a vector's growth factor is 1.5x, and vectors have random lengths, then on average they'll be halfway between the previous and the next reallocation. Even for a 2x growth factor, 2 / 1.5 = 33% overhead.

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