C++ map insertion and lookup performance and storage overhead

Question

I would like to store a mapping of an integer key to a float value in-memory.

I have roughly 130 million keys (and, accordingly, 130 million v

Answer 1

Most compilers ship with a non-standard (but working) hash_map (or unordered_map) that might be faster for you. It's coming in C++0x (is in tr1) and it is also (as always) in boost already.

GCC did too, but I haven't done C++ on that for .. 12 years .., but it should still be in there somewhere.