How to compare two values in generic method?

Question

I need to create generic method which returns greater of two params. Operators > and < don't work. Here is signature of my method:

public static T Greater<T>(ref T a, ref T b)
{
    if (a > b) 
    {
       return a;
    }
    else 
    {
       return b;
    }
}

I'm quite rookie in C# and totally new in generic types.

Or http://stackoverflow.com/questions/390900/cant-operator-be-applied-to-generic-types-in-c. — Patrick Hofman, Sep 24 '14 at 11:25
As a non related comment, to shorten your method you can write: `return a.CompareTo(b) > 0 ? a : b;` — Yuval Itzchakov, Sep 24 '14 at 11:25
These aren't quite duplicates. Those are about comparing equality. This question is about order / precedence. — vcsjones, Sep 24 '14 at 11:26
Not related to your question, but why are those `ref`s there? They don't seem necessary, since you're not modifying the parameters. — svick, Sep 24 '14 at 11:39

score 10 · Answer 1 · answered Sep 24 '14 at 11:23

10

Since the T can be any type there is no guarantee that T will overload > or < operators. Adding a IComparable<T> constraint you are saying that T must implement IComparable<T> which contains a method named CompareTo, then you can use that method to compare your objects instead:

public static T Greater<T>(ref T a, ref T b) where T : IComparable<T>
{
    if(a.CompareTo(b) > 0) return a;
    else return b;
}

answered Sep 24 '14 at 11:23

Selman Genç

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Thanks, that works. With your help learning C# is easier! :) – Box Sep 24 '14 at 11:27

How to compare two values in generic method?

1 Answers1