C# Linq All & Any working differently on blank array

Question

Consider following linq example with blank array:

When Any() returns false as there is no number greater than zero how can All() return true conveying all numbers greater than zero ?

var arr = new int[] { };
Console.WriteLine(arr.Any(n => n > 0)); //false 
Console.WriteLine(arr.All(n => n > 0)); //true 

question from:https://stackoverflow.com/questions/38899289/c-sharp-linq-all-any-working-differently-on-blank-array

Answer 1

Seems logical to me.

• All: Are all numbers in arr greater than zero (meaning there is no number not greater than zero) => true
• Any: Is there any number in arr that is greater than zero => false

But more important, according to Boolean Algebra:

arr.All(n => n > 0); 

gives true, because it should be the logical opposite of

arr.Any(n => !(n > 0));

which gives false (actually this is what the above two points say).