Solved

Flagged enum equation logic

Posted on 2007-11-13
16
313 Views
Last Modified: 2013-11-07
HI,

Suppose I have:

[Flags]
enum Fruits
{
     None = 0,
     Apple = 1,
     Orange = 2,
     Peach = 4,
     Banana = 8
}

and then I initialize a avriable:

Fruits fruits = Fruits.Apple | Fruits.Orange | Fruits.Banana;

how do I then find out if "fruits" variable is equal to "Banana"

It would be really great if I could do something like this:

if (fruits == Fruits.Banana)
{
     // do something
}

but unfortunately, it's not that convenient.
0
Comment
Question by:davidlars99
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 7
  • 5
  • 3
  • +1
16 Comments
 
LVL 8

Accepted Solution

by:
Chumad earned 200 total points
ID: 20275309
if ((fruits && Fruits.Banana)  == Fruits.Banana) {
   //do something
}

0
 
LVL 22

Assisted Solution

by:JimBrandley
JimBrandley earned 150 total points
ID: 20275319
It isn't much more difficult. This works:
if ((fruits & Fruits.Banana) > 0)
{
   // We have a bananna or fruit salad.
}

Jim
0
 
LVL 2

Expert Comment

by:JumpsInLava
ID: 20275327
Sorry, not a C# coder, and not sure of the syntax, but with bitwise stuff you want to OR stuff together, and use AND to figure out if it is part of...

if (Convert.ToBoolean(fruits & Fruits.Banana))
{
     // do something
}
0
Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

 
LVL 22

Expert Comment

by:JimBrandley
ID: 20275333
Chumad's post will work if you change it to:
if ((fruits & Fruits.Banana)  == Fruits.Banana) {
   //do something
}

Jim
0
 
LVL 2

Expert Comment

by:JumpsInLava
ID: 20275335
lol...three of the same but different answers in three mins!  must be a record.
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275418
this return match too even though Fruits.Peach is not part of the group:

Fruits fruits = Fruits.Apple | Fruits.Orange | Fruits.Banana;

if ((fruits & Fruits.Peach)  == Fruits.Peach)
{
   //do something
}

0
 
LVL 2

Assisted Solution

by:JumpsInLava
JumpsInLava earned 150 total points
ID: 20275505
:-S
you sure?  ...this works for me

    public partial class Form1 : Form
    {
        [Flags]
        enum Fruits
        {
            None = 0,
            Apple = 1,
            Orange = 2,
            Peach = 4,
            Banana = 8
        }

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Fruits fruits = Fruits.Apple | Fruits.Orange | Fruits.Banana;
            if ((fruits & Fruits.Peach) == Fruits.Peach)
            {
                MessageBox.Show("hey");
            }
        }
    }
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275535
If this works then you are not suppose to see the message box right?
0
 
LVL 22

Expert Comment

by:JimBrandley
ID: 20275598
I do not see this behavior. Running this code:
public enum TestEnum
{
   None = 0,
   Apple = 1,
   Bananna = 2,
   Orange = 4,
   Pineapple = 8
};

string hello = "We have Banannas";

TestEnum te1 = TestEnum.Apple | TestEnum.Bananna;
if ((te1 & TestEnum.Orange) == TestEnum.Orange)
{
   hello = "Now we have a Oranges?";
}

When completed, we still have banannas, and not oranges.

Jim
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275647
So, are you getting into the IF block or not?
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275665
You're right, it works... :)
0
 
LVL 22

Expert Comment

by:JimBrandley
ID: 20275679
I did not alter the string.

Jim
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275759
That's right, you didn't.

Thanks for your help!!!
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20275797
One last thing:

How do I determine if a flagged enum has more than one group?
0
 
LVL 22

Expert Comment

by:JimBrandley
ID: 20275971
Something like this will work, cannot think of a better way offhand.

public bool IsSalad( Fruits selection )
{
   int count = 0;
   if ((selection & Fruits.Apple) == Fruits.Apple)
      count++;
   if ((selection & Fruits.Banana) == Fruits.Banana)
      count++;
   etc.
   return (count > 1);
}
0
 
LVL 13

Author Comment

by:davidlars99
ID: 20290092
what about this?

if ((int)selection) > 1)
{
   // multiple selection
}
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Entity Framework is a powerful tool to help you interact with the DataBase but still doesn't help much when we have a Stored Procedure that returns more than one resultset. The solution takes some of out-of-the-box thinking; read on!
Exception Handling is in the core of any application that is able to dignify its name. In this article, I'll guide you through the process of writing a DRY (Don't Repeat Yourself) Exception Handling mechanism, using Aspect Oriented Programming.
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…

624 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question