Validate all the values of a enum with Linq in C#

Question

Well, I have this:

public enum letters {a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z}

And I want to do this:

letters letter = letters.a;

if(letter == a || letter == b || letter = c || //to z...) {
//countinue...
}

how can I do this with a LINQ expression?

EDIT:

I realised that I can return true directly, but if I want to except one, for example letter "d" and other letter like "g", how can I do that?

EDIT2:

I like weird answers for it, I don't like answers like "use this: "||" or something similar... so teach me how to do it with linq. IsDefined is a good way to do it :P

Thanks in advanced.

Answer 1

If you want to check against one as your update asks:

but if I want to excepting one, for example letter "d", how can I do that?

Then simply do

if (letter != Letters.D)
{
    // not D
}

---

Your initial question will always be true because letter cannot not be one of Letters .#

---

To check multiple values, you can do the following

var invalidLetters = new[] { Letters.A, Letters.B };

if (invalidLetters.Contains(letter))
{
    // letter is Letters.A or Letters.B
}

Answer 2

I realised that I can return true directly, but if I want to except one, for example letter "d", how can I do that?

You can use Where + Contains :

var allLetters = Enum.GetValues(typeof(letters)).Cast<letters>();
var allButD = allLetters.Where(l => l != letters.d);
if (allButD.Contains(letter))
{ 

}

Answer 3

You can try this:

 if(Enum.IsDefined(typeof(letters), letter))
 {
     return 1;
 }
 else
 {
     return 0;
 }

Answer 4

Try

    letters letter = letters.a;

    if (Enum.IsDefined(typeof(letters), letter))
    { 

    }