Linq let Concat

let：

 String[] strs = {  "A penny saved is a penny earned.",
             "The early bird catches the worm.",
             "The pen is mightier than the sword." };
            var result = from s in strs  //s是数组strs中的一个元素
                         let word = s.Split(' ')  //word是s句子中的单词数组
                         from a in word  //a是word单词数组中的一个单词
                         let w = a.ToLower()  //w是a单词的小写
                         where w[0] == 't'
                         select word;
            foreach (var r in result)
            {
                var words = r.ToArray();
                foreach (var w in words)
                {
                    Console.Write(w + "||");
                }
                Console.WriteLine();
                Console.WriteLine("=======================");
            }

2.concat:

 连接数组

var result = list.Select(q => q.Name).Concat(dogs.Select(o => o.Name));
            ap.ShowArray(result.ToArray());

注意必须都是同一类型的，例如上面就是字符串类型

连接对象数组

var result = list.Where(q => q.ID < 4);
            var result2 = list.Where(q => q.ID > 7);
            var result3 = result.Concat(result2);
            ap.Show(result3.ToList());

有相同数据的情况

   var result = list.Where(q => q.ID < 8);
            var result2 = list.Where(q => q.ID > 4);
            var result3 = result.Concat(result2);
            ap.Show(result3.ToList());