C#: bitwise operator in enum (Custom Authorization in MVC)

Question

I'm currently reading an article , but I do not really understand how this work with the logical operator. Can anyone explain this to me? eg. If I want to have 4 level securities with customer, employee, supervisor and Admin. ``` [Serializable] [Flags] public enum WebRoles { customer= 1 << 0, employee= 1 << 1, supervisor = 1 << 2, Admin = 2 << 3 } ``` and then how I should implement the following logic. ``` if (Roles != 0 && ((Roles & role) != role)) return false; ``` Can anyone provide me some knowledge of this implementation? Thank you very much. Daoming

Accepted Answer

This example uses the bitwise shift operator: "<<". This operator takes the bits and shifts them. For example, "1 << 3" results in the number 8. So, in binary,

```
customer =    0001
employee =    0010
supervisor =  0100
admin =       1000 (I think this was supposed to read 1 << 3)
```

Now, you can assign people multiple roles using the bitwise-or operator. This would be a single vertical-bar "|". The bitwise or combines the two numbers bit-by-bit, setting each bit that is set in either of the two operands.

```
myRole = customer | employee = 0011
```

The if-statement you have is intended to tell whether someone has a particular role. It uses bitwise-and: "&". Bitwise-and combines the two numbers, setting a bit only if the bit is set in both the operands.

C#: bitwise operator in enum (Custom Authorization in MVC)

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