Fórum ➡ Prime numbers implemented using LINQ statements AND using FOR loop ♦, C#

Fórum ➡ Prime numbers implemented using LINQ statements AND using FOR loop ♦

//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

#define USE_LINQ_STATEMENTS
    
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

// aljodav
// http://rextester.com/users/376

// in reply to the MSDN thread:
// http://bit.ly/2ecZbzL

// Prime numbers using Sieve of Eratosthenes algorithm.
// Implementations through LINQ statements and through for-loop.

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            const int maxNumber=12345; // user defined
     
            if(maxNumber<2)throw new Exception("Invalid Maximum Number");
            
            Console.Write("Prime numbers up to {0}:\n\n2 ",maxNumber);
            
            if(maxNumber>2){
                
                List<int> nonPrimes=new List<int>(); // helper list
                
#if USE_LINQ_STATEMENTS
                
                Enumerable
                    .Range(3,maxNumber-2)
                    .Where(x=>(x&1)==1&&false==nonPrimes.Contains(x))
                    .Select(x=>{
                        nonPrimes.AddRange(Enumerable.Range(3,maxNumber/x).Where(y=>(y&1)==1).Select(y=>y*x));
                        return x;
                    })
                    .ToList()
                    .ForEach(x=>Console.Write("{0} ",x))
                    ;
                
#else
                    
                for(int i=3;i<=maxNumber;i+=2){
                    if(false==nonPrimes.Contains(i)){
                        Console.Write("{0} ",i);
                        for(int j=3;j<=maxNumber/i;j+=2)nonPrimes.Add(j*i);
                    }
                }
                
#endif
                
            }
            
            Console.WriteLine("\n\nHello, world!");
        }
    }
}


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