I think you can… You’ll have to add operators for bitmasky things. I didn’t do it here but you could easily overload any relational operator. /** * */ // NOTE: I changed to a more descriptive and consistent name // This needs to be a real bitmask type. enum class file_permissions : int { no_perms … Read more
The construct if ((mask & FLAG3) == FLAG3) tests if all bits in FLAG3 are present in mask; if (mask & FLAG3) tests if any are present. If you know FLAG3 has exactly 1 bit set, they are equivalent, but if you are potentially defining compound conditions, it can be clearer to get into the … Read more
The answer to your question is to use the Bitwise & like this: SELECT * FROM UserTable WHERE Roles & 6 != 0 The 6 can be exchanged for any combination of your bitfield where you want to check that any user has one or more of those bits. When trying to validate this I … Read more
Bits and Bytes In computing, numbers are internally represented in binary. This means, where you use an integer type for a variable, this will actually be represented internally as a summation of zeros and ones. As you might know, a single bit represents one 0 or one 1. A concatenation of eight of those bits … Read more
Splendid question! Firstly, let’s make some assumptions about “better”. I’m assuming you don’t much care about disk space – a bitmask is efficient from a space point of view, but I’m not sure that matters much if you’re using SQL server. I’m assuming you do care about speed. A bitmask can be very fast when … Read more
Briefly, a bitmask helps to manipulate the position of multiple values. There is a good example here; Bitflags are a method of storing multiple values, which are not mutually exclusive, in one variable. You’ve probably seen them before. Each flag is a bit position which can be set on or off. You then have a … Read more
Declaring Bitmasks: Alternatively to assigning absolute values (1, 2, 4, …) you can declare bitmasks (how these are called) like this: typedef enum : NSUInteger { FileNotDownloaded = (1 << 0), // => 00000001 FileDownloading = (1 << 1), // => 00000010 FileDownloaded = (1 << 2) // => 00000100 } DownloadViewStatus; or using modern … Read more
It’s quite simple actually. First a bit of code to demonstrate how it can be implemented. If you don’t understand anything about what this code is doing or how it works, feel free to ask additional questions in the comments: const FLAG_1 = 0b0001; // 1 const FLAG_2 = 0b0010; // 2 const FLAG_3 = … Read more
I see values from at least a handful of different enumerations in there… My first thought was to approach the problem by splitting the permissions up in logical groups (RuleGroupPermissions, RulePermissions, LocationPermissions, …), and then having a class (WebAgentPermissions) exposing a property for each permission enum type. Since the permission values seem repetitive, you could … Read more
The traditional way to do this is to use the Flags attribute on an enum: [Flags] public enum Names { None = 0, Susan = 1, Bob = 2, Karen = 4 } Then you’d check for a particular name as follows: Names names = Names.Susan | Names.Bob; // evaluates to true bool susanIsIncluded = … Read more