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c++enumsflagsenum-flagsbitflags

Compact non-repetitive way for an ALL flag in enums that represent bitflags in C++

I often use enums for bitflags like the following

enum EventType {
    NODE_ADDED = 1 << 0,
    NODE_DELETED = 1 << 1,
    LINK_ADDED = 1 << 2,
    LINK_DELETED = 1 << 3,
    IN_PIN_ADDED = 1 << 4,
    IN_PIN_DELETED = 1 << 5,
    IN_PIN_CHANGE = 1 << 6,
    OUT_PIN_ADDED = 1 << 7,
    OUT_PIN_DELETED = 1 << 8,
    OUT_PIN_CHANGE = 1 << 9,

    ALL = NODE_ADDED | NODE_DELETED | ...,
};

Is there a clean less repetitive way to define an ALL flag that combines all other flags in an enum? For small enums the above works well, but lets say there are 30 flags in an enum, it gets tedious to do it this way. Does something work (in general) like this

ALL = -1

?

Solution

  • Use something that'll always cover every other option, like:

    ALL = 0xFFFFFFFF

    Or as Swordfish commented, you can flip the bits of an unsigned integer literal:

    ALL = ~0u

    To answer your comment, you can explicitly tell the compiler what type you want your enum to have:

    enum EventType : unsigned int