Test for multiple values in an if statement in C#

Question

Is there a shorthand syntax in C# to make this:

if ((x == 1) || (x==2) || (x==5) || (x==13) || (x==14))

... shorter? Something like (hypothetically)

if (x in {1, 2, 5, 13, 14})

I "feel" like it exists, I'm just coming up short mentally and Googly. In reality I have to test a bunch of enums frequently and it's just unreadable. I also hate to make a little helper function if the language supports it already.

Thanks in advance!

Edit

There are clever solutions involving lists... but I was hoping for a pure logical construct of some kind. If it doesn't exist, so be it. Thanks!

http://stackoverflow.com/questions/3907299/c-sharp-if-statements-matching-multiple-values — Jeremy D, Mar 07 '12 at 01:43
It is not necessary to use inner quotes: `if ( x == 1 || x == 2 || x == 5...)` except if you have used Pascal/Delphi several years and has "professional distortion". — i486, Nov 20 '15 at 10:36

score 13 · Accepted Answer · answered Mar 07 '12 at 01:44

13

Try this:

if ((new[]{1, 2, 5, 13, 14}).Contains(x)) ...

answered Mar 07 '12 at 01:44

Sergey Kalinichenko

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Yeah... I suppose that would be slightly cleaner than what I have. In the absence of a super-simple syntax, I just use a helper function like 3907299 that "Jeremy D" posted. Thanks anyway. – Adamlive Mar 07 '12 at 01:52
`HashSet` would be faster than `Array`! =) – Sergey Vyacheslavovich Brunov Mar 07 '12 at 05:51

Brad Christie · Answer 2 · 2012-03-07T02:00:54.677

2

Though I think the if statement is fine, and making code brief for breifness's sake is useless, here goes:

First approach, assuming you want to go the LINQ route:

if ((new[]{1,2,5,13,14}).Contains(x)){
}

Second approach, ArrayList

if ((new System.Collections.ArrayList(new[]{1,2,5,13,14})).Contains(x)){
}

Third approach, List:

if ((new System.Collections.Generic.List<Int32>(new[]{1,2,5,13,14})).Contains(x)){
}

But keep in mind all of these add more overhead (and really don't add much as far as readability, given the performance consideration).

oh, and working example of the above.

edited Mar 07 '12 at 02:00

answered Mar 07 '12 at 01:47

Brad Christie

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Good point about the overhead. This will run far more often than I need to read it. – Adamlive Mar 07 '12 at 01:53

score 2 · Answer 3 · answered Mar 07 '12 at 05:50

I would like to recommend using HashSet(T) Class to check whether the element belongs to the set of elements.

Furthermore, as HashSet<T> is an associative container, its lookup complexity is O(1), i.e. constant time: HashSet(Of T).Contains Method, while Array and List<T> has linear time lookup: O(n). So, HashSet<T> would be the better for lookup.

HashSet<int> numbers = new HashSet<int> { 1, 2, 5, 13, 14 };
int x = 1;
if (numbers.Contains(x))
{
    Console.WriteLine("Contains!");
}

score 0 · Answer 4 · answered Mar 07 '12 at 01:44

0

No, there is no support for comparing directly like that. However, you could use LINQ methods such as Contains(). I could provide an example but it sort of depends how the data items are originally stored.

answered Mar 07 '12 at 01:44

Jonathan Wood

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score 0 · Answer 5 · answered Mar 07 '12 at 01:51

0

You could perhaps do something like this:

if( Array.LastIndexOf(new int[]{1, 2,3,4}, x) != -1)
{
    //YOUR CODE HERE
}

Not tested, but I believe this would work.

edit Looks like a similar response has already been posted.

answered Mar 07 '12 at 01:51

A.Midlash

143
4

Test for multiple values in an if statement in C#

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