Question

Assuming I have the following enum

[Flags]
enum Options
{
    Option1 = 1 << 0, 
    Option2 = 1 << 1, 
    Option3 = 1 << 2
}

And I were to set a variable as follows

var options = 0;
options |= Options.Option1; 
options |= Options.Option3; 

// now options should equal Option1 + Option3
// I then store that single value in the database
myDatabase.Options.Submit(options);

How do I then parse “Options” in order to get the original values back?

public List<Options> ParseOptions(Options options)
{
    // Not sure how to parse the options.
}

Answer 1

You could use the Enum.HasFlag() method to see if a particular flag is set. Just go through all the individual values testing if it is set.

var value = Options.Option1 | Options.Option3;
foreach (Options flag in Enum.GetValues(typeof(Options)))
{
    if (value.HasFlag(flag))
    {
        // do something with the flag
    }
}

Note that the HasFlag() method was added to .NET 4. It is however logically equivalent to this:

public static bool HasFlag(this Enum value, Enum flag)
{
    return (value & flag) == flag;
}