nowne

This is an amazing tool, I use it almost daily. Whenever I want to test an idea, or see what is going on in the assembly, I go straight to godbolt.

It will likely link, since both clang and gcc will perform RVO on bar(), so the copy constructor won't be called.

Linear probing works by initially hashing the value, call it h(x), then if there is a collision, it checks h(x)+1, h(x)+2, ..., h(x) + k, until it finds a open slot. Lookup works in the same way, and deletion is a bit more complicated.

This model plays nicely with the cache, although its downside is there tend to be more "runs" of contiguous filled slots in the hash table. This method still provably takes an expected insert/lookup time of O(1) with a 5-wise independent hash function and a load factor smaller than 1.

The problem with that method is that it doesn't have data access locality, while linear probing does. Linear probing ends up being more efficient because it is easy on the cache.

There are countably infinite number of functions. A simple proof is that each function can be represented as a string, and there are countably infinite number of strings for a finite alphabet. You could also argue that functions are equivalent to Turing machines, and there are a finite number of Turing machines.

That wouldn't solve much, if anything at all, see Kerckhoffs's Principle[1]. The standard encryption algorithms perform perfectly well to the best of our knowledge, why make your own encryption algorithm and risk getting it wrong?

[1] http://en.wikipedia.org/wiki/Kerckhoffs's_principle