How to iterate through "set" enum in .NET C# 3.5

Question

I know in .NET 4 you can use HasFlag

Is there any alternative to the following in .NET 3.5?

if ((enumVar & EnumType.ValueOne) == EnumType.ValueOne)
{
  // someMethod(1) or someMethod(EnumType.ValueOne)
}
if ((enumVar & EnumType.ValueTwo) == EnumType.ValueTwo)
{
  // someMethod(2) or someMethod(EnumType.ValueTwo)
}
if ((enumVar & EnumType.ValueThree) == EnumType.ValueThree)
{
  // someMethod(3) or someMethod(EnumType.ValueThree)
}
if ((enumVar & EnumType.ValueFour) == EnumType.ValueFour)
{
  // someMethod(4) or someMethod(EnumType.ValueFour)
}

...etc for each value in the enum? You must be able to use a for..each loop to accomplish this where the argument to someMethod is the index of the loop?

[Flags]
enum EnumType
{
  ValueOne = 1
  , ValueTwo = 2
  , ValueThree = 4
  , ValueFour = 8
}

EDIT: Only worth looking at the accepted answer, the rest of the comments/answers can be safely ignored.

@RhysW thats the whole point. I gave ifs and asked if they could be rewritten as a loop — Greg Tarr, Jan 21 '13 at 15:53
Apologies, i assumed youre reply was directed at Chris, did not see the loop requirement — , Jan 21 '13 at 15:54

score 5 · Accepted Answer · answered Jan 21 '13 at 15:48

5

You should be able to write something like this. You can make it generic if you want, but there's no way to set the constraint to be enum, so you'd have to check that yourself with reflection.

public static bool HasFlag(YourEnum source, YourEnum flag)
{
    return (source & flag) == flag;
}

answered Jan 21 '13 at 15:48

Honza Brestan

10,637
2
32
43

2

shame about that, I guess its why hasFlag was introduced – Greg Tarr Jan 21 '13 at 15:49
2

@GregT If you "cheat", you can constrain to an enum. See [another answer in another thread](http://stackoverflow.com/a/1409873/1336654) where the project Unconstrained Melody is linked. – Jeppe Stig Nielsen Jan 21 '13 at 21:52

score 3 · Answer 2 · answered Jan 21 '13 at 15:49

3

foreach (EnumType enumType in Enum.GetValues(typeof(EnumType)))
{
    if(enumVar.HasFlag(enumType)) 
    {
        Console.WriteLine(enumTpye.ToString());
    }
}

answered Jan 21 '13 at 15:49

Matt

1,648
12
22

I did say not to use HasFlag - this is .NET 3.5 – Greg Tarr Jan 21 '13 at 15:50
Apologies - didn't read that. In which case you need to use the & operator. – Matt Jan 21 '13 at 15:51
@lazyberezovsky HasFlag was introduced in .net 4 he is using an earlier version – Jan 21 '13 at 15:53
2

if(enumVar & enumType){...} should produce the same result as hasFlag – nakchak Jan 21 '13 at 16:13
yes, but HasFlag can be parameterized but the other notation cannot, so cannot be done in a loop – Greg Tarr Jan 21 '13 at 17:10

MethodMan · Answer 3 · 2013-01-21T15:59:24.307

0

You can do something like this to do a foreach loop of EnumType

foreach (EnumType enumType in Enum.GetValues(typeof(EnumType)))
{
    if (enumType.HasFlag(enumType))
    {
        Console.WriteLine(enumType.ToString());
    }
}

This will return ValueOne, ValueTwo, ValueThree.. etch not sure if this is what you are looking for please test and let me as well as others know

edited Jan 21 '13 at 15:59

answered Jan 21 '13 at 15:44

MethodMan

18,625
6
34
52

That doesn't check whether the enum value is set? – Greg Tarr Jan 21 '13 at 15:45
1

You could add a conditional statement in that loop I hope that I am understanding your question correctly.. you could also add a Switch statement if you like – MethodMan Jan 21 '13 at 15:45
can you give example code? it can't use HasFlag as this is .NET 3.5 – Greg Tarr Jan 21 '13 at 15:46
GregT I misunderstood your question I gave an answer that would return the values of the EnumType in a forloop I apologize – MethodMan Jan 21 '13 at 15:49

score 0 · Answer 4 · answered Jan 21 '13 at 15:48

0

switch enumvar
{
case valueOne:
{
//do some thing
breake;
}
case valuetwo:
{
//do some thing else
break;
}
default:
break;
    }

answered Jan 21 '13 at 15:48

Maghraby

11
1

How to iterate through "set" enum in .NET C# 3.5

4 Answers4