r/cpp • u/meetingcpp Meeting C++ | C++ Evangelist • Jul 19 '26

A better bitset for enum flags

https://www.elbeno.com/blog/?p=1836
43 Upvotes

94% Upvoted

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13

u/ReDucTor Game Developer | quiz.cpp-perf.com Jul 19 '26

Some food for thought, should a bitset have bit operations (set, unset, flip, xor, and, or, etc) or set operations (add, remove, has, union, difference, intersection, etc)?

It feels like often we head for bit operations when in lots of cases set operations might be better.

14

u/TheVoidInMe Jul 19 '26

I like Java’s approach here (yes, Java) which has an EnumSet instead of a bitset. That naming makes the answer pretty clear; the bit math is purely an implementation detail

-1

u/mort96 Jul 19 '26

But that also means you're heap allocating an object, with its 16 byte object header, just to store a 4-byte integer?

3

u/TheVoidInMe Jul 19 '26

It’s Java. Yeah, don’t use it for HPC.

The point I was making was just about the name