Question

How can I compare a enum to a variable if the enum contains mulitple possible values?

Ex: for the following enum

typedef enum {
    EnumValueA = 2,
    EnumValueB = 3,
    EnumValueC = 4,
    EnumValueD = (0 | -1)
} EnumValues;

When comparing a variable like BOOL result = (a == EnumValueD) I get NO if int a = 0 and YES if int a = -1.

Also, this enum is inside a component so I just can’t change it..How

How can I make this comparison return YES for both 0 and -1?

Answer 1

Your question is based on a misunderstanding. The line

EnumValueD = (0 | -1)

does not indicate “multiple values”. That is a “bitwise-or” operator: it performs an operation (bitwise) on the numbers zero and minus one, and yields just one answer. It’s a curious bit of code (probably having to do with integer byte size issues), but you only need to test against -1. (If you really want to be safe you could test against (0|-1), I suppose.)

Moral: Don’t confuse logical-or || with the bitwise-or operator |.