Wednesday, October 21, 2009

IComparable.Between Extension Method

IComparableT-SQL has a between statement to make it easier to determine if a test object occurs between two other objects. I needed similar functionality in C# but I didn't know what the type the objects would be; however, I did know they would always be IComparable. Obviously, there's no real need for an extension method here, but it did make things a bit more convenient.

Like T-SQL, the between extension method is inclusive and the start parameter doesn't have to be lower than the end parameter.

Here's what some test cases look like:
5.Between(1, 10) // true
5.Between(10, 1) // true
5.Between(10, 6) // false
5.Between(5, 5)) // true

Here's the method:
public static bool Between<T>(this T target, T start, T end)
    where T : IComparable
    if (start.CompareTo(end) == 1)
        return (target.CompareTo(end) >= 0) && (target.CompareTo(start) <= 0);

    return (target.CompareTo(start) >= 0) && (target.CompareTo(end) <= 0);

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