Getting common flags enum value in c#

问题

Say I have the below enum

[Flags]
enum Letters
{
     A = 1,
     B = 2,
     C = 4,
     D = 8,
     E = 16,
     F = 32,
     AB = A | B,
     All = A | B | C,
}

If I have the variables:

var s = Letters.A | Letters.B | Letters.D;
var p = Letters.A | Letters.C | Letters.D | Letters.E;

What I want is to get the common values between these two enums so in this case it should be A | D. Can some one please tell me how I can achieve this.

Thanks

回答1:

You can get that using the binary & (and) operator:

var s = Letters.A | Letters.B | Letters.D;
var p = Letters.A | Letters.C | Letters.D | Letters.E;
var sAndp = s & p; // This will give you only the common values ( A & D)

回答2:

Just as you use | to get a union of values, you can use the & to get the intersection:

var s = Letters.A | Letters.B | Letters.D;
var p = Letters.A | Letters.C | Letters.D | Letters.E;

var intersection = s & p;  // A | D
var union = s | p;         // All | D | E

回答3:

Here is the result:

    var result =  s & p;

回答4:

If that's suitable for you it will return List of individual flags

 static IEnumerable<Enum> GetFlags(Enum input)
    {
        foreach (Enum value in Enum.GetValues(input.GetType()))
            if (input.HasFlag(value))
                yield return value;
    }

GetFlags(s).Intersect(GetFlags(p))

来源：https://stackoverflow.com/questions/51975514/getting-common-flags-enum-value-in-c-sharp