What spelling is that flags enum values having 0x as prefix?

Question

I have found this enum with a Flags attribute:

    [Flags]
    public enum Technology
    {
       None = 0x0000,
        X1 = 0x0001,
        X2 = 0x0002,
        X3 = 0x0004,
        X4 = 0x0008,
        X5 = 0x0010,
        X6 = 0x0020,       
    }

The values assigned to the enum members, what spelling is it?

And would that be the same?

    [Flags]
    public enum Technology
    {
       None = 0,
        X1 = 1,
        X2 = 2,
        X3 = 4,
        X4 = 8,
        X5 = 10,
        X6 = 20,       
    }

If yes, why is X5 not 16 twice the value from X4, because that logic takes place from X1 to X4!

`0x0020` is *hexadecimal* (please, note `0x` *prefix*) which is `32` *decimal*; so `X5 = 16, X6 = 32` — Dmitry Bychenko, Nov 06 '19 at 10:55
Does this answer your question? [What do numbers using 0x notation mean?](https://stackoverflow.com/questions/8186965/what-do-numbers-using-0x-notation-mean) — Sinatr, Nov 06 '19 at 11:20
Possible duplicate of [What do numbers using 0x notation mean?](https://stackoverflow.com/questions/8186965/what-do-numbers-using-0x-notation-mean) and [What does the Flags Enum Attribute mean in C#?](https://stackoverflow.com/questions/8447/what-does-the-flags-enum-attribute-mean-in-c) — , Nov 06 '19 at 11:34

Dmitry Bychenko · Accepted Answer · 2019-11-06T11:28:40.800

4

Well, 0x prefix means hexadecimal, not just decimal. So the equivalent declarations will be

hexadecimal (0x prefix)

[Flags]
public enum Technology
{
   None = 0x0000,
     X1 = 0x0001,
     X2 = 0x0002,
     X3 = 0x0004,
     X4 = 0x0008,
     X5 = 0x0010, // 0x0010 == 1 * 16 + 0 == 16
     X6 = 0x0020, // 0x0020 == 2 * 16 + 0 == 32       
}

decimal

[Flags]
public enum Technology
{
   None =  0,
     X1 =  1,
     X2 =  2,
     X3 =  4,
     X4 =  8,
     X5 = 16,
     X6 = 32,       
}

binary (note 0b prefix)

[Flags]
public enum Technology
{
   None = 0b000000,
     X1 = 0b000001,
     X2 = 0b000010,
     X3 = 0b000100,
     X4 = 0b001000,
     X5 = 0b010000,
     X6 = 0b100000,       
}

edited Nov 06 '19 at 11:28

answered Nov 06 '19 at 10:59

Dmitry Bychenko

180,369
20
160
215

I think C#8 should enforce `[Flags]` being in binary notation :) – tymtam Nov 06 '19 at 11:41
@tymtam why and how could it be ? a number is a number, no matter how it was written – Cid Nov 06 '19 at 12:57

score 3 · Answer 2 · edited Jun 20 '20 at 09:12

0x0000 is 0 in Hexadecimal. Which means that 0x0010 is actually 16 in decimal - making the x5 and x6 members of both enums different.

In order to make them the same, in the second enum you need the values 16 and 32 for x5 and x6.

The 0x prefix is what tells the c# compiler that the value is hexadecimal - as documented in the Integer Literals paragraph in Integral numeric types (C# reference):

Integer literals can be

decimal: without any prefix

hexadecimal: with the 0x or 0X prefix

binary: with the 0b or 0B prefix (available in C# 7.0 and later)

What spelling is that flags enum values having 0x as prefix?

2 Answers2