Question

for each number in A and each number in B if their difference is more than 3 ,add the new number

A={6,7,10}
B={2,3}
result={4,5,4,8,7}

for example :

6-2=4 true Add 4

6-3=3 false

7-2=5 true Add 5

my attempt :

  var result = A.Select((a, i) => new
  {
   desired = a - B[i] > 3 ? a - B[i] :0

   });

Answer 1

It sounds like you want:

var query = from a in A
            from b in B
            let diff = a - b
            where diff > 3
            select diff;

Or in dot notation, which drops out really neatly:

var query = A.SelectMany(a => B, (a, b) => a - b)
             .Where(x => x > 3);

With your test data:

using System;
using System.Linq;

class Test
{
    public static void Main()        
    {
        int[] A = {6, 7, 10};
        int[] B = {2, 3};

        var query = A.SelectMany(a => B, (a, b) => a - b)
                     .Where(x => x > 3);

        foreach (var result in query)
        {
            Console.WriteLine(result);
        }
    }
}