IEnumerable result = null;             List a = new List ();             List b = new List() { "a","b","c","d"};             List c = new List() { "c", "d", "e", "f" };             //a b取交集             result = a.Intersect(b);             Console.WriteLine($"a.Intersect(b)");             Console.WriteLine($"a,b取交集,a:空,b:\"{string.Join(",", b)}\",结果:{string.Join(",",result)}");             Console.WriteLine("===========");             //a b取并集             result = a.Union(b);             Console.WriteLine($"a.Union(b)");             Console.WriteLine($"a,b取并集,a:空,b:\"{string.Join(",", b)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             //a b取差集             result = a.Except(b);             Console.WriteLine($"a.Except(b)");             Console.WriteLine($"a,b取差集,a:空,b:\"{string.Join(",", b)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             //b a取差集             result = b.Except(a);             Console.WriteLine($"b.Except(a)");             Console.WriteLine($"b,a取差集,a:空,b:\"{string.Join(",", b)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===============================================");

            //b,c取交集             result = b.Intersect(c);             Console.WriteLine($"b.Intersect(c)");             Console.WriteLine($"b,c取交集,b:\"{string.Join(",", b)}\",c:\"{string.Join(",", c)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             //b,c取并集             result = b.Union(c);             Console.WriteLine($"b.Union(c)");             Console.WriteLine($"b,c取并集,b:\"{string.Join(",", b)}\",c:\"{string.Join(",", c)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             //b,c取差集             result = b.Except(c);             Console.WriteLine($"b.Except(c)");             Console.WriteLine($"b,c取差集,b:\"{string.Join(",", b)}\",c:\"{string.Join(",", c)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             //b,c取差集             result = c.Except(b);             Console.WriteLine($"c.Except(b)");             Console.WriteLine($"c,b取差集,b:\"{string.Join(",", b)}\",c:\"{string.Join(",", c)}\",结果:{string.Join(",", result)}");             Console.WriteLine("===========");             Console.Read();