How to create a Between Extension Method

Question

I have a variable whose value is populated at runtime. I want to check whether that value is between two same datatype values (say lowest and highest) or not using an Extension Method.

I want to check like

int a = 2; //here static but is can be changed at runtime

if(a.Between(0,8))
   DoSomething();
else
   DoNothing();

If a is 0 or 8 or any value between them, it should return true.

If a is (-1 or less) or (9 or greater) then it should return false

i want to create an extension method like

public static bool Between<T1>(this T1 val1, T1 lowest, T1 highest) where ????
{
    What code to write here???? 
}

Just a remark : this has nothing to do with Linq, it's just "Fluent" — Raphaël Althaus, May 09 '12 at 06:52
Many people think linq means extension methods, as the linq ones are the one people are most familiar with. A total misunderstanding, but quite common. — Falanwe, May 09 '12 at 07:12

score 16 · Accepted Answer · edited May 23 '17 at 11:53

16

You can do it like this:

public static bool Between<T>(this T actual, T lower, T upper) where T : IComparable<T>
{
    return actual.CompareTo(lower) >= 0 && actual.CompareTo(upper) <= 0;
}

Reference here

Or if you want to do it on a collection you can do this:

public static IEnumerable<TSource> Between<TSource, TResult>
(
    this IEnumerable<TSource> source, Func<TSource, TResult> selector,
    TResult lowest, TResult highest
)
    where TResult : IComparable<TResult>
{
    return source.OrderBy(selector).
        SkipWhile(s => selector.Invoke(s).CompareTo(lowest) < 0).
        TakeWhile(s => selector.Invoke(s).CompareTo(highest) <= 0 );
}

Reference here

Usage:

var tenTo40 = list.Between(s => s, 10, 40);

edited May 23 '17 at 11:53

Community

1
1

answered May 09 '12 at 06:50

Arion

31,011
10
70
88

Last part from here http://www.codeproject.com/Articles/310581/A-Between-extension-method-for-Linq-in-Csharp – Nikhil Agrawal May 09 '12 at 06:54
Oops.. I did forget the references. Thanks for pointing that out – Arion May 09 '12 at 06:56
Edited your answer to include <= with highest comparison because i want to check for both values inclusive – Nikhil Agrawal May 09 '12 at 07:09

score 2 · Answer 2 · answered May 09 '12 at 06:54

2

Maybe like this:

public static bool Between<T1, T2>(this T1 val1, T2 lowest, T2 highest) where T1 : IComparable where T2 : IComparable {
    return val1.CompareTo(lowest) > 0 && val1.CompareTo(highest) < 0;
}

answered May 09 '12 at 06:54

Malmi

387
3
8

i think it's `<=` isntead of `<` and `>=` isntead of `>` – fubo Jul 07 '16 at 13:24

score 1 · Answer 3 · answered May 09 '12 at 06:49

Mixing types will make it harder, eg. if T1 is datetime and t2 is int then what behaviour do you expect?

Using only one type all the way you can use the IComparable interface

public static bool Between<T>(this T self, T lower,T higher) where T : IComparable
{
    return self.CompareTo(lower) >= 0 && self.CompareTo(higher) <= 0;
}

How to create a Between Extension Method

3 Answers3

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