How do I implement my special ordering as CompareTo

Question

So I have following struct

public struct Foo
{
    public readonly int FirstLevel;
    public readonly int SecondLevel;
    public readonly int ThirdLevel;
    public readonly int FourthLevel;
}

Somewhere I do the following

var sequence = new Foo[0];
var orderedSequence = sequence
    .OrderBy(foo => foo.FirstLevel)
    .ThenBy(foo => foo.SecondLevel)
    .ThenBy(foo => foo.ThirdLevel)
    .ThenBy(foo => foo.FourthLevel);

Now I would like to implement System.IComparable<Foo> to take eg. advantage of .Sort() of Foo[].

How do I transfer the logic (from my special/wired OrderBy/ThenBy) to int CompareTo(Foo foo)?

Answer 1

What about something like:

public struct Foo : IComparable<Foo>
{
    public readonly int FirstLevel;
    public readonly int SecondLevel;
    public readonly int ThirdLevel;
    public readonly int FourthLevel;

    public int CompareTo(Foo other)
    {
        int result;

        if ((result = this.FirstLevel.CompareTo(other.FirstLevel)) != 0)
            return result;
        else if ((result = this.SecondLevel.CompareTo(other.SecondLevel)) != 0)
            return result;
        else if ((result = this.ThirdLevel.CompareTo(other.ThirdLevel)) != 0)
            return result;
        else 
            return this.FourthLevel.CompareTo(other.FourthLevel);
    }
}