Finding out if an int is equal to any member of a set of ints?

Question

I know I can do it like this:

if(myint == 1 || myint == 2 || myint ==3) //etc...

But I feel like there must be a more efficient way to code this. Is there a way to possibly make a statement like this work?

if(myint.Contains(1 || 2 || 3 || 4))

possible duplicate of [Combining multiple conditional expressions in C#](http://stackoverflow.com/questions/6390138/combining-multiple-conditional-expressions-in-c-sharp) — 48klocs, Aug 21 '13 at 20:35

score 14 · Answer 1 · answered Aug 21 '13 at 19:55

14

you can do inverse

new List<int>{1,2,3,4}.Contains(myInt)

Note that there is also Enumerable.Any, but Contains would work for .net 2.0 too.

answered Aug 21 '13 at 19:55

Tigran

6

You don't need List, any IEnumerable will do, including a plain old array. – Preston Guillot Aug 21 '13 at 19:57
4

+1. Note if set is constant and big enough `HashSet` would give better performance. – Alexei Levenkov Aug 21 '13 at 19:58
Note that this syntax requires C# >= 3: http://msdn.microsoft.com/en-us/library/vstudio/bb384062.aspx – cheesemacfly Aug 21 '13 at 20:04

Khan · Accepted Answer · 2013-08-21T20:01:43.660

8

Close, try the following.
It will take a collection and return true if your int is in the collection:

if (new[] { 1, 2, 3, 4 }.Contains(myint))
    //Do something

new[] { 1, 2, 3, 4 } represents an array of integers.

The Contains method is an extension of IEnumerable<T> and will be available to anything that implements it.

edited Aug 21 '13 at 20:01

answered Aug 21 '13 at 19:56

Khan

2 Answers2