Duplicate enum values

Question

Is it allowed to have duplicate enum values in c?

Answer 1

Akshay I think you answered your own question: Yes (duh, or it wouldn't run).

What's an enum? A numeric constant. The purpose? Believe it or not laziness. WTF? Okay, not 100%, there's other purposes like abstraction (eyup), but it boils down to this:
enum pee {A=10, B, C, D};
Is shorthand for:
const int A=10, B=11, C=12, D=13;
Which is clever since our compiler generates the consts declarations.

Now you understand _what_ it is, you understand _why_ the code runs; Valen.H. ~ it works because two constants _can_ share a value:
const int X = 10;
const int Y = 10;

No problem. In the lifespan of the code, Y may need to be changed to 11, but for now it's 10.

Why not #define X 10 then? First, the preprocessor substitutes _all_ occurrences of X so you may get mangled code, second, they become literal 10 _before_ compilation. These caveats are a topic unto themselves.

Bottom line: Nothing wrong, not a hack, not a language flaw.

Answer 2

I don't think its possible in any language. Why would someone want that?

Answer 3

enum test_1 {
ZERO,
ONE,
TWO,
// TWO (Error for redeclaration)
};

// But

enum test_2 {
ZERO = 0,
ONE = 1,
TWO = 2,
THREE = 2, // A-OK for their values
};

Answer 4

A=3,
B=2,
C

After the last explicit assignment (B = 2), the enum's internal will continue to assign values incrementally (3, 4, 5, ...).

Answer 5

Valen.H. ~ please go through this code you will get idea what i am actually asking.

https://code.sololearn.com/c1yj6W3xG8Cb/?ref=app