Question

I am unable to decide which STL container to use in the following case:

1. I want to preserve the order of insertion of the elements
2. The elements in the container have to be unique.

Is there any readymade container available for this? I don’t want to use a vector and then perform a std::find before doing a push_back every time.

Answer 1

Boost MultiIndex should be able to do exactly what you want – you can just use one sequenced index to get the ‘ordered by insertion order’ requirement, and either a hashed_unique or ordered_unique index to get the uniqueness requirement.