十四、C# 支持标准查询运算符的集合接口

 1     class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5             var patent1 = new
 6             {
 7                 Title = "xxm1",
 8                 YearOfPublication = "1977"
 9             };
10             var patent2 = new
11             {
12                 Title = "xxm2",
13                 YearOfPublication = "1978"
14             };
15             var patent3 = new
16             {
17                 patent1.Title,
18                 //重新命名属性
19                 Year = patent2.YearOfPublication
20             };
21  
22             Console.WriteLine(patent1.Title + ":" + patent1.YearOfPublication);
23             Console.WriteLine(patent2.Title + ":" + patent2.YearOfPublication);
24             Console.WriteLine(patent3.Title + ":" + patent3.Year);
25  
26             Console.WriteLine();
27             Console.WriteLine(patent1);
28             Console.WriteLine(patent2);
29             Console.WriteLine(patent3);
30  
31             Console.ReadLine();
32  
33  
34  
35         }
36     }
37  
38 输出:
39 xxm1:1977
40 xxm2:1978
41 xxm1:1978
42  
43 { Title = xxm1, YearOfPublication = 1977 }
44 { Title = xxm2, YearOfPublication = 1978 }
45 { Title = xxm1, Year = 1978 }

1 string text=" this is a test of the ...";
2 //<====>
3 var text="this is a test of the ...";

 1     class Program
 2     {
 3         static void Main(string[] args)
 4         {
 5  
 6             List<string> sevenWorldBlunders = new List<string>();
 7             sevenWorldBlunders = new List<string>()
 8             {
 9                 "Wealth without work",
10                 "Pleasure without conscience",
11                 "Knowledge without character",
12             };
13  
14  
15             Print(sevenWorldBlunders);
16  
17         }
18         private static void Print<T>(IEnumerable<T> items)
19         {
20             foreach (T item in items)
21             {
22                 Console.WriteLine(item);
23             }
24  
25         }
26     }

  1     class Program
  2     {
  3         static void Main(string[] args)
  4         {
  5             IEnumerable<Patent> patents = PatentData.Patents;
  6  
  7             Print(patents);
  8  
  9             Console.WriteLine();
 10  
 11             IEnumerable<Inventor> inventors = PatentData.Inventors;
 12  
 13             Print(inventors);
 14  
 15             Console.ReadLine();
 16  
 17  
 18  
 19  
 20         }
 21         public static void Print<T>(IEnumerable<T> items)
 22         {
 23             foreach (T item in items)
 24             {
 25                 Console.WriteLine(item);
 26             }
 27         }
 28         //专利类
 29         public class Patent
 30         {
 31             public string Title { get; set; }
 32  
 33             public string YearOfPublication { get; set; }
 34             public string ApplicationNumber { get; set; }
 35             public long[] InventorIds { get; set; }
 36             public override string ToString()
 37             {
 38                 return string.Format("{0}({1})", Title, YearOfPublication);
 39             }
 40         }
 41         //发明者类
 42         public class Inventor
 43         {
 44             public long Id { get; set; }
 45             public string Name { get; set; }
 46             public string City { get; set; }
 47             public string State { get; set; }
 48             public string Country { get; set; }
 49             public override string ToString()
 50             {
 51                 return string.Format("{0}({1},{2})", Name, City, State);
 52             }
 53         }
 54  
 55         //实际数据
 56         public static class PatentData
 57         {
 58             public static readonly Inventor[] Inventors = new Inventor[] {
 59                 new Inventor(){
 60                     Name="Benjamin Franklin",City="Philadelphia",
 61                     State="PA",Country="USA",Id=1
 62                 },
 63                 new Inventor(){
 64                     Name="Orville Wright",City="Kitty Hawk",
 65                     State="NC",Country="USA",Id=2
 66                 },
 67                 new Inventor(){
 68                     Name="Wilbur Wright",City="Kitty Hawk",
 69                     State="NC",Country="USA",Id=3
 70                 },
 71                 new Inventor(){
 72                     Name="Samuel Morse",City="New York",
 73                     State="NY",Country="USA",Id=4
 74                 },
 75                 new Inventor(){
 76                     Name="George Stephenson",City="Wylam",
 77                     State="Northumberland",Country="UK",Id=5
 78                 },
 79                 new Inventor(){
 80                     Name="John Michaelis",City="Chicago",
 81                     State="IL",Country="USA",Id=6
 82                 },
 83                 new Inventor(){
 84                     Name="Mary Phelps Jacob",City="New York",
 85                     State="NY",Country="USA",Id=7
 86                 },
 87             };
 88  
 89             public static readonly Patent[] Patents = new Patent[] {
 90                 new Patent(){
 91                     Title="Bifocals",YearOfPublication="1784",
 92                     InventorIds=new long[]{1}
 93                 },
 94                 new Patent(){
 95                     Title="Phonograph",YearOfPublication="1877",
 96                     InventorIds=new long[]{1}
 97                 },
 98                 new Patent(){
 99                     Title="Kinetoscope",YearOfPublication="1888",
100                     InventorIds=new long[]{1}
101                 },
102                 new Patent(){
103                     Title="Electrical Telegraph",YearOfPublication="1837",
104                     InventorIds=new long[]{4}
105                 },
106                 new Patent(){
107                     Title="Flying machine",YearOfPublication="1903",
108                     InventorIds=new long[]{2,3}
109                 },
110                 new Patent(){
111                     Title="Steam Locomotive",YearOfPublication="1815",
112                     InventorIds=new long[]{5}
113                 },
114                 new Patent(){
115                     Title="Droplet deposition apparatus",YearOfPublication="1989",
116                     InventorIds=new long[]{6}
117                 },
118                 new Patent(){
119                     Title="Backless Brassiere",YearOfPublication="1914",
120                     InventorIds=new long[]{7}
121                 },
122             };
123         }
124     }

 1             IEnumerable<Patent> patents = PatentData.Patents;
 2             bool result;
 3             patents = patents.Where(patent =>
 4                 {
 5                     if (result = patent.YearOfPublication.StartsWith("18"))
 6                     {
 7                         Console.WriteLine("Where StartsWith 18 :" + patent);
 8                     }
 9                     return result;
10                 });
11             Console.WriteLine("1. Patents prior to the 1900s are:");
12             foreach (Patent patent in patents)
13             {
14  
15             }
16             Console.WriteLine();
17             Console.WriteLine("2. A second listing of patents prior to the 1900s:");
18             Console.WriteLine("   There are {0} patents prior to 1900.", patents.Count());
19  
20             Console.WriteLine();
21             Console.WriteLine("3. A third listing of patents prior to the 1900s:");
22             patents = patents.ToArray();
23             Console.Write("   There are  ");
24             Console.WriteLine("{0} patents prior to 1900.", patents.Count());

 1             IEnumerable<Patent> items = null;
 2             Patent[] patents = PatentData.Patents;
 3  
 4             items = patents.OrderBy(patent => patent.YearOfPublication)
 5                 .ThenBy(patent => patent.Title);
 6             Print(items);
 7  
 8             Console.WriteLine();
 9  
10             items = patents.OrderByDescending(patent => patent.YearOfPublication)
11                 .ThenByDescending(patent => patent.Title);
12             Print(items);
13  

  1     class Program
  2     {
  3         static void Main(string[] args)
  4         {
  5  
  6             Department[] departments = CorporateData.Departments;
  7             Employee[] employees = CorporateData.Employees;
  8  
  9             var items = employees.Join(
 10                 departments,//关联的数据
 11                 employee => employee.DepartmentId,//联接时的参考属性
 12                 department => department.Id,//联接时的参考属性
 13                 (employee, department) => new //返回的数据
 14                 {
 15                     employee.Id,
 16                     employee.Name,
 17                     employee.Title,
 18                     Department = department
 19  
 20                 });
 21             Print(items);
 22  
 23             Console.ReadLine();
 24  
 25  
 26  
 27  
 28         }
 29         public static void Print<T>(IEnumerable<T> items)
 30         {
 31             foreach (T item in items)
 32             {
 33                 Console.WriteLine(item);
 34             }
 35         }
 36  
 37  
 38         //部门类
 39         public class Department
 40         {
 41             public long Id { get; set; }
 42             public string Name { get; set; }
 43             public override string ToString()
 44             {
 45                 return string.Format("{0}", Name);
 46             }
 47         }
 48  
 49         //员工类
 50         public class Employee
 51         {
 52             public int Id { get; set; }
 53             public string Name { get; set; }
 54             public string Title { get; set; }
 55             public int DepartmentId { get; set; }
 56             public override string ToString()
 57             {
 58                 return string.Format("{0}({1})", Name, Title);
 59             }
 60         }
 61  
 62         //实际数据
 63         public static class CorporateData
 64         {
 65             public static readonly Department[] Departments = new Department[] {
 66                 new Department()
 67                 {
 68                     Name="Corporate",Id=0
 69                 },
 70                 new Department()
 71                 {
 72                     Name="Corporate",Id=1
 73                 },
 74                 new Department()
 75                 {
 76                     Name="Engineering",Id=2
 77                 },
 78                 new Department()
 79                 {
 80                     Name="Information Technology",Id=3
 81                 },
 82                 new Department()
 83                 {
 84                     Name="Research",Id=4
 85                 },
 86                 new Department()
 87                 {
 88                     Name="Marketing",Id=5
 89                 },
 90             };
 91             public static readonly Employee[] Employees = new Employee[] {
 92                 new Employee()
 93                 {
 94                     Name="Mark Michaelis",
 95                     Title="Chief Computer Nerd",
 96                     DepartmentId=0
 97                 },
 98                 new Employee()
 99                 {
100                     Name="Michael Stokesbary",
101                     Title="Senior Computer Wizard",
102                     DepartmentId=2
103                 },
104                 new Employee()
105                 {
106                     Name="Brian Jones",
107                     Title="Enterprise Integration Guru",
108                     DepartmentId=2
109                 },
110                 new Employee()
111                 {
112                     Name="Jewel Floch",
113                     Title="Bookkeeper Extraordinaire",
114                     DepartmentId=1
115                 },
116                 new Employee()
117                 {
118                     Name="Robert Stokesbary",
119                     Title="Expert Mainframe Engineer",
120                     DepartmentId=3
121                 },
122                 new Employee()
123                 {
124                     Name="Paul R.Bramsman",
125                     Title="Programmer Extraordinaire",
126                     DepartmentId=2
127                 },
128                 new Employee()
129                 {
130                     Name="Thomas Heavey",
131                     Title="Software Architect",
132                     DepartmentId=2
133                 },
134                 new Employee()
135                 {
136                     Name="John Michaelis",
137                     Title="Inventor",
138                     DepartmentId=4
139                 },
140  
141             };
142         }
143  
144     }
145  
146 输出：
147 { Id = 0, Name = Mark Michaelis, Title = Chief Computer Nerd, Department = Corpo
148 rate }
149 { Id = 0, Name = Michael Stokesbary, Title = Senior Computer Wizard, Department
150 = Engineering }
151 { Id = 0, Name = Brian Jones, Title = Enterprise Integration Guru, Department =
152 Engineering }
153 { Id = 0, Name = Jewel Floch, Title = Bookkeeper Extraordinaire, Department = Co
154 rporate }
155 { Id = 0, Name = Robert Stokesbary, Title = Expert Mainframe Engineer, Departmen
156 t = Information Technology }
157 { Id = 0, Name = Paul R.Bramsman, Title = Programmer Extraordinaire, Department
158 = Engineering }
159 { Id = 0, Name = Thomas Heavey, Title = Software Architect, Department = Enginee
160 ring }
161 { Id = 0, Name = John Michaelis, Title = Inventor, Department = Research }

 1             IEnumerable<Employee> employees = CorporateData.Employees;
 2             IEnumerable<Department> departments = CorporateData.Departments;
 3  
 4             IEnumerable<IGrouping<int, Employee>> groupedEmployees =
 5                 employees.GroupBy(employee => employee.DepartmentId);
 6             foreach (IGrouping<int, Employee> employeeGroup in groupedEmployees)
 7             {
 8                 Console.WriteLine();
 9                 foreach (Employee employee in employeeGroup)
10                 {
11                     Console.WriteLine("\t"+employee);
12                 }
13                 Console.WriteLine("\t Count:"+employeeGroup.Count());
14             }
15  

 1             IEnumerable<Employee> employees = CorporateData.Employees;
 2             IEnumerable<Department> departments = CorporateData.Departments;
 3  
 4  
 5             var items = departments.GroupJoin(
 6                 employees,//关联的对象数组
 7                 department => department.Id,//关联的键
 8                 employee => employee.DepartmentId,//关联的键
 9                 (department, departmentEmployees) => new//返回的数据
10                 {
11                     department.Id,
12                     department.Name,
13                     Employees = departmentEmployees
14                 });
15             foreach (var item in items)
16             {
17                 Console.WriteLine("部门：{0}", item.Name+":");
18                 foreach (Employee employee in item.Employees)
19                 {
20                     Console.WriteLine("\t"+employee);
21                 }
22             }

 1             string[] text = { "a b", "c d", "e f" };
 2             var items = text.Select(
 3                 item => item.Split(‘ ‘)
 4                 );
 5             foreach (string[] strs in items)
 6             {
 7                 foreach (string str in strs)
 8                 {
 9                     Console.WriteLine("\t"+str);
10                 }
11             }
12 换成SelectMany
13             string[] text = { "a b", "c d", "e f" };
14             var items = text.SelectMany(
15                 item => item.Split(‘ ‘)
16                 );
17             foreach (var item in items)
18             {
19                 Console.WriteLine("\t" + item);
20             }