October 04, 2016
Good afternoon,

I have just written a function, which uses the "set_union()" function for merging two sorted std::vectors.
The issue is that this is very slow, and I think I understand why: the function "set_union()" takes two input vectors and generates an output vector, which means that every element in the resulting vector needs to be allocated in memory.

What I'm actually looking for, is a function which merges the values of one std::vector into another one. Here the number of allocations should be far less and I expect the performance of this function being far better.

Does anybody know if such a function exists and how to use it? (I'm having quite some trouble getting STL functions to work)

Thanks in advance