enum as flags - compare to byte

[todorov-fkt]

Hello everyone,

I have a field which is 1 byte long and is used to store different flags
(according to specs) - it is the flags bit in the ID3 tag header. So
0xabc00000 represents the byte, where only bits a,b and c have any meaning,
the other bits are always 0. I also have the following:
[Flags] enum ID3_Header_Flags {
NoFlag = 0x00000000,
FlagC = 0x00100000,
FlagB = 0x01000000,
FlagA = 0x10000000
};

When I compare the byte with the flag like
if (tagHeader[5] & ID3_Header_Flags.FlagX) where tagHeader is a byte[],
tagHeader[5] is the flags byte, and FlagX represents any of the Flags in the
enum, I get the following error:
"The operator '&' can not be used on Operands of type byte and
test02.Form1.ID3_Header_Flags".

And if I do [Flags] enum ID3_Header_Flags : byte, then the flags are too big
to fit in a byte....

Can you give me any hints what I'm doing wrong and how to solve my problem?
Any help is highly appreciated. Thanks in advance.

[Morten Wennevik]

Hi Todorov,

There are several errors in your code.
First, I assume you want binary flags, but 0x?? are hexadecimal numbers so any of your numbers are far too big to be compared to a byte. Try something like

[Flags] enum ID3_Header_Flags
{
NoFlag = 0x00000000,
FlagC = 0x00000001,
FlagB = 0x00000002,
FlagA = 0x00000004
};

Furthermore, comparing two numbers using & will not produce a boolean value. You will need to do something like

if (((ID3_Header_Flags)tagHeader[5] & ID3_Header_Flags.FlagX) > 0)

This casts the byte in tagHeader to a ID3_Header_Flags type and if number1 & number2 is larger than 0 we have a match. This of course will be 0 no matter what if you compare to NoFlag.

--
Happy coding!
Morten Wennevik [C# MVP]