Define values that can be combined

Asked Jun 26 '17 at 07:39

Active Jun 26 '17 at 07:39

Viewed 45 times

I would like to define an enum with different states that can be combined. I found that I could use bitset but I am not sure about how I can combine them.

So here is my enum :

enum Mode {
  NONE = 0,
  MODE_1 = 1 << 0,
  MODE_2 = 1 << 1,
  MODE_3 = 1 << 2
};

And what I want to do is to have a value that includes for instance mode_1 and mode_2.

asked Jun 26 '17 at 07:39

klaus

What's the problem exactly? This *is* how you define bit flags. – StoryTeller - Unslander Monica Jun 26 '17 at 07:40
Let's say I have a function with parameter Mode. If I want to call this function with this parameter set to a value that corresponds to MODE_1 and MODE_2, how can I do this ? – klaus Jun 26 '17 at 07:50
@klaus Supposed you have a function declaration like `void foo(uint8_t modes);` you'll call it like `foo(MODE_1 | MODE_2);`. – πάντα ῥεῖ Jun 26 '17 at 07:54
@πάντα ῥεῖ : thank you - and is it better to define the header like I did or like this : https://stackoverflow.com/questions/1448396/how-to-use-enums-as-flags-in-c ? – klaus Jun 26 '17 at 07:55
@klaus Read the duplicate to get known all of the relevant information. – πάντα ῥεῖ Jun 26 '17 at 07:56
1

@πάνταῥεῖ For type safety it would be better to have `void foo(Mode modes)` which could be achieved by overloading bitwise operators as suggested in the duplicate. – zett42 Jun 26 '17 at 07:59
@zett42 Yes, that's correct. I just wanted to give a short example. – πάντα ῥεῖ Jun 26 '17 at 08:01
@klaus See here: https://meta.stackexchange.com/questions/10841/how-should-duplicate-questions-be-handled/ – πάντα ῥεῖ Jun 26 '17 at 09:15

Define values that can be combined

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