There is a comparator for sorting in the reverse order.
class Comp<T> : IComparer<T> where T : IComparable<T> { public int Compare(T x, T y) { return -x.CompareTo(y); //return y - x; } } Question: Is it possible to make it so that it is possible to return y - x as a result of the comparison, as in the commented section (this makes it difficult to make a generic type T)
Not. Operators cannot be used with generic types, since they are static and cannot be restricted by using the interface.
As for the subtraction for comparison, and the unary minus - there may be problems due to overflow. Although the standard Enumerable.OrderByDescending already contains this bug: http://codeblog.jonskeet.uk/2015/03/02/backward-compatibility-pain/
PS: In fact, the subtraction method can be shoved by forcing to determine the types and look for the operator during the execution of the method, but this will be a very big impact on performance, especially given that comparators are usually used when sorting.
And the best way to do a reverse comparator is
public int Compare(T x, T y) { return y.CompareTo(x); } 
Such a possibility does not exist because at the current moment it is impossible to express in C # a constraint for a generic type that guarantees the existence of one or another operator. (However, support for this is discussed by the language development team.)
However, your code with subtraction is incorrect even if T = int . Imagine that x == int.MaxValue , y == -1 , then x - y will become negative due to overflow.
Correctly in the idea so:
return -Math.Sign(x.CompareTo(y)); 
Source: https://ru.stackoverflow.com/questions/416661/
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