C# Linq: Combine multiple .Where() with an *OR* clause

Question

I have been searching a lot about my current problem but I could not find a real answer to solve that issue.

I am trying to build a LINQ Query that produces the followi

Answer 1

First, create some helper extension methods to easier combine two Func predicates:

 public static Func And(this Func left, Func right) 
     => a => left(a) && right(a);

 public static Func Or(this Func left, Func right)
     => a => left(a) || right(a);

Then you can use them to chain predicates:

var list = Enumerable.Range(1, 100);

Func predicate = v => true; // start with true since we chain ANDs first

predicate = predicate.And(v => v % 2 == 0); // numbers dividable by 2
predicate = predicate.And(v => v % 3 == 0); // numbers dividable by 3
predicate = predicate.Or(v => v % 31 == 0); // numbers dividable by 31

var result = list.Where(predicate);

foreach (var i in result)
    Console.WriteLine(i);

Output:

6
12
18
24
30
31
36
42
48
54
60
62
66
72
78
84
90
93
96