Couldn't understand Enum Flags with 0x2 values

Question

I am trying to understand a portion of code but couldn't understand it so far ...

[Flags] public enum Products { Pepsi = 0x1, Coca = 0x2, Miranda = 0x3, Dew = 0x4, Wine = 0x5 } Products pp = (Products)12; pp.HasFlag(Products.Dew); ==> True pp.HasFlag(Products.Miranda); ==> False pp.HasFlag(Products.Coca); ==> False

I want to know why pp.HasFlag(Products.Dew) is True and pp.HasFlag(Products.Miranda) is False . I thought it is working as 0x1 = 1, 0x2 = 2, 0x3 = 4, 0x4 = 8, 0x5 = 16. Kindly guide me what is going on

I don't really see a reason to downvote this question. At least not whithout stating a reason... — nozzleman
– nozzleman, Commented Jan 20, 2016 at 6:27

Rob · Accepted Answer · 2016-01-20 06:20:54Z

4

You're mistaken about 0x means. 0x5 does not equal 16, it equals 5. 0x lets you write hexadecimal, so that you could write 0xA = 10.

Change your definition to be:

public enum Products { Pepsi = 1, Coca = 2, Miranda = 4, Dew = 8, Wine = 16 }

Thus, 12 would represent the flag Dew and Miranda

answered Jan 20, 2016 at 6:20

Rob♦

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4 Comments

Waqar Ahmed Over a year ago

HasFlag(Products.Dew) is True ?

Rob Over a year ago

@WaqarAhmed Yes, because 12 represents 8+4 (which is Dew and Miranda).

Waqar Ahmed Over a year ago

According to my code Why pp.HasFlag(Products.Dew) is True and pp.HasFlag(Products.Miranda) is False?

Rob Over a year ago

@WaqarAhmed Because 12 is 1100 in binary. Miranda (3) is 0011. Dew (4) is 0100. 0100 & 1100 yields 0100, so the flag is on for Dew. 0011 & 1100 yields 0000, so the flag is off for miranda.

Dmitrii Bychenko · Accepted Answer · 2016-01-20 06:36:59Z

Your initial declaration equals to

[Flags] public enum Products { Pepsi = 0x1, Coca = 0x2, Miranda = Coca | Pepsi, // equals to 0x3 since 0x3 == 0x2 | 0x1 Dew = 0x4, Wine = Dew | Pepsi // equals to 0x5 since 0x5 == 0x4 | 0x1 }

You probably want

[Flags] public enum Products { Pepsi = 0x1, Coca = 0x2, Miranda = 0x4, Dew = 0x8, Wine = 0x10 }

Community · Accepted Answer · 2017-05-23 11:52:05Z

You should read this topic. Your flags are little bit incorrect. For example:

Pepsi | Cola = Miranda 0001 | 0010 = 0011

Logically right flags:

[Flags] public enum Products { Pepsi = 0x1, Coca = 0x2, Miranda = 0x4, Dew = 0x8, Wine = 0x0A }

Arin Ghazarian · Accepted Answer · 2016-01-20 06:34:31Z

In order to understand Flags it's better to convert each flag value to its binary representation. So in your case we have:

[Flags] public enum Products { Pepsi = 0x1, //--> 0001 Coca = 0x2, //--> 0010 Miranda = 0x3, //--> 0011 Dew = 0x4, //--> 0100 Wine = 0x5 // --> 0101 }

then when 12 (which in binary is '1100') casted to Products enum you can clearly see that the flag bit for Dew (which is 0100) is on (or 1 in binary). In other words, every product which its third bit from right is 1 has Dew in it.

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