LINQ to Object

 1 using System;

 2 using System.Collections.Generic;

 3 using System.Linq;

 4 using System.Collections;

 5

 6 namespace Demo1

 7 {

 8     class Program

 9     {

10

11         static void Main(string[] args)

12         {

13             Console.WriteLine("简单查询");

14             string[] currentVideoGames = { "Morrowind", "Uncharted 2", "Fallout  3", "Daxter", "System Shock 2" };

15             IEnumerable<string> subSet = from g in currentVideoGames where g.Contains(" ") orderby g select g;

16             foreach (string s in subSet)

17                 Console.WriteLine(s);

18

19             int [] numbers = {10,20,30,1,2,4,8 };

20             List<Person> personList = new List<Person>

21             {

22                 new Person{Age = 15, Name = "Lucy"},

23                 new Person{Age = 13, Name = "Tom"},

24                 new Person{Age = 18, Name = "Bob"},

25                 new Person{Age = 20, Name = "Jake"}

26             };

27             Console.WriteLine("简单条件查询");

28             var resu = from i in numbers where i < 10 select i;

29             foreach (var s in resu)

30                 Console.WriteLine(s);

31             Console.WriteLine("复合条件查询");

32             var myPersons = from p in personList where p.Age >= 18 && p.Name!="Jake" select p;

33             foreach (var p in myPersons)

34                 Console.WriteLine("Age = {0}, Name = {1}",p.Age, p.Name);

35

36             Console.WriteLine("把ArrayList转换成一个兼容于 IEnumerable<T>的类型");

37             ArrayList persons = new ArrayList()

38             {

39                 new Person{Age = 13, Name = "Tom" },

40                 new Person{Age = 20, Name = "Jake"}

41             };

42             var personsEnum = persons.OfType<Person>();

43             var personTom = from p in personsEnum where p.Name == "Tom" select p;

44             foreach (var p in personTom)

45                 Console.WriteLine("Age = {0}, Name = {1}",p.Age,p.Name);

46

47             Console.WriteLine("使用 ofType<T> 筛选数据");

48             ArrayList myStuff = new ArrayList();

49             myStuff.AddRange(new object[]{10,400,8,false,new Person(), "string data"});

50             var myInts = myStuff.OfType<int>();

51             foreach (int i in myInts)

52                 Console.WriteLine("Int  value: {0}",i);

53

54             Console.WriteLine("将查询结果投影到新数据类型");

55             var nameList = from n in personList select new { n.Name };

56             foreach (var n in nameList)

57                 Console.WriteLine(n.Name);

58             //    Except() 返回容器与比较的容器的不同之处

59             //    Intersect() 返回容器与比较的容器的相同之处

60             //    union() 合并成员，不允许重复(任何地方)

61             //    Concat()  直接连接，不检查(如果想检查，加上 Distinct() 即可)

62             //    Count(), Max(), Min(), Sum(), Average() ...s

63             Console.WriteLine("常用方法");

64             List<string> str1 = new List<string> { "Yugo", "Aztec", "BMW"};

65             List<string> str2 = new List<string>{"BMW","Saab","Aztec"};

66             Console.WriteLine("Use Except()");

67             foreach(var i in  str1.Except(str2))

68                 Console.WriteLine(i);

69             Console.WriteLine("Use Intersect()");

70             foreach (var i in str1.Intersect(str2))

71                 Console.WriteLine(i);

72             Console.WriteLine("Use Union()");

73             foreach (var i in str1.Union(str2))

74                 Console.WriteLine(i);

75             Console.WriteLine("Use Concat()");

76             foreach (var i in str1.Concat(str2))

77                 Console.WriteLine(i);

78             Console.ReadLine();

79         }

80     }

81     public class Person

82     {

83         public int Age { get; set; }

84         public string Name { get; set; }

85     }

86 }

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