Csharp/CSharp Tutorial/LINQ/Max
Содержание
Get the Min and max value from a query
<source lang="csharp">using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; using System.Reflection; class Salary {
int _id; int _year; double _salary; public int ID { get { return _id; } set { _id = value; } } public int Year { get { return _year; } set { _year = value; } } public double SalaryPaid { get { return _salary; } set { _salary = value; } }
} class Employee {
int _id; int _idRole; string _lastName; string _firstName; public int ID { get { return _id; } set { _id = value; } } public int IDRole { get { return _idRole; } set { _idRole = value; } } public string LastName { get { return _lastName; } set { _lastName = value; } } public string FirstName { get { return _firstName; } set { _firstName = value; } }
} class Role {
int _id; string role; public int ID { get { return _id; } set { _id = value; } } public string Role { get { return role; } set { role = value; } }
} public class MainClass {
public static void Main() { List<Employee> people = new List<Employee> { new Employee { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"}, new Employee { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}, new Employee { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"}, new Employee { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"} }; List<Role> roles = new List<Role> { new Role { ID = 1, Role = "Manager" }, new Role { ID = 2, Role = "Developer" } }; List<Salary> salaries = new List<Salary> { new Salary { ID = 1, Year = 2004, SalaryPaid = 10000.00 }, new Salary { ID = 1, Year = 2005, SalaryPaid = 15000.00 }, new Salary { ID = 1, Year = 2005, SalaryPaid = 15000.00 } }; var query = from p in people join s in salaries on p.ID equals s.ID where p.ID == 1 select s.SalaryPaid; Console.WriteLine("Minimum Salary:"); Console.Write(query.Min()); Console.WriteLine("Maximum Salary:"); Console.Write(query.Max()); }
}</source>
Grouped Max
<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {
public static void Main() { List<Product> products = GetProductList(); var categories = from p in products group p by p.Category into g select new { Category = g.Key, MostExpensivePrice = g.Max(p => p.UnitPrice) }; Console.Write(categories); } static List<Product> GetProductList() { List<Product> empTree = new List<Product>(); empTree.Add(new Product { ProductName = "A", Category = "O", UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 2 }); empTree.Add(new Product { ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 3 }); empTree.Add(new Product { ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 4 }); empTree.Add(new Product { ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 5 }); empTree.Add(new Product { ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 6 }); return empTree; } static List<Customer> GetCustomerList() { List<Product> empTree = new List<Product>(); empTree.Add(new Product { ProductName = "A", Category = "O", UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); empTree.Add(new Product { ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 }); List<Customer> l = new List<Customer>(); l.Add(new Customer { CompanyName = "A", Region = "R1", UnitsInStock = 1, Orders = empTree, CustomerId = 0 }); l.Add(new Customer { CompanyName = "B", Region = "R2", UnitsInStock = 2, Orders = empTree, CustomerId = 1 }); l.Add(new Customer { CompanyName = "C", Region = "R3", UnitsInStock = 3, Orders = empTree, CustomerId = 2 }); l.Add(new Customer { CompanyName = "D", Region = "R4", UnitsInStock = 4, Orders = empTree, CustomerId = 3 }); l.Add(new Customer { CompanyName = "E", Region = "R5", UnitsInStock = 5, Orders = empTree, CustomerId = 4 }); return l; }
} class Customer : IComparable<Customer> {
public string CompanyName { get; set; } public string Region { get; set; } public List<Product> Orders { get; set; } public int UnitsInStock { get; set; } public int CustomerId { get; set; } public override string ToString() { return String.Format("Id: {0}, Name: {1}, Region: {3}", this.CustomerId, this.rupanyName, this.Region); } int IComparable<Customer>.rupareTo(Customer other) { if (other == null) return 1; if (this.CustomerId > other.CustomerId) return 1; if (this.CustomerId < other.CustomerId) return -1; return 0; }
} class Product : IComparable<Product> {
public string ProductName { get; set; } public string Category { get; set; } public int UnitPrice { get; set; } public int UnitsInStock { get; set; } public int Total { get; set; } public DateTime OrderDate { get; set; } public int Id { get; set; } public override string ToString() { return String.Format("Id: {0}, Name: {1} , Category: {3}", this.Id, this.ProductName, this.Category); } int IComparable<Product>.rupareTo(Product other) { if (other == null) return 1; if (this.Id > other.Id) return 1; if (this.Id < other.Id) return -1; return 0; }
}</source>
Max on int array
<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {
public static void Main() { int[] myInts = new int[] { 974, 2, 7, 1374, 27, 54 }; int maxInt = myInts.Max(); Console.WriteLine(maxInt); }
}</source>
Max on object list
<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {
public int birthYear; public string firstName; public string lastName; public static Employee[] GetEmployees() { Employee[] actors = new Employee[] { new Employee { birthYear = 1964, firstName = "K", lastName = "R" }, new Employee { birthYear = 1968, firstName = "O", lastName = "W" }, new Employee { birthYear = 1960, firstName = "J", lastName = "S" }, new Employee { birthYear = 1964, firstName = "S", lastName = "B" }, }; return (actors); }
} public class MainClass {
public static void Main() { int youngestEmployeeAge = Employee.GetEmployees().Max(a => a.birthYear); Console.WriteLine(youngestEmployeeAge); }
}</source>
Max on Object list array
<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {
public int birthYear; public string firstName; public string lastName; public static Employee[] GetEmployees() { Employee[] actors = new Employee[] { new Employee { birthYear = 1964, firstName = "K", lastName = "R" }, new Employee { birthYear = 1968, firstName = "O", lastName = "W" }, new Employee { birthYear = 1960, firstName = "J", lastName = "S" }, new Employee { birthYear = 1964, firstName = "S", lastName = "B" }, }; return (actors); }
} public class MainClass {
public static void Main() { string lastAlphabetically = Employee.GetEmployees().Max(a => a.lastName); Console.WriteLine(lastAlphabetically); }
}</source>
Max on String array
<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {
public static void Main() { string[] presidents = {"G", "H", "H", "H", "H", "J"}; string maxName = presidents.Max(); Console.WriteLine(maxName); }
}</source>
Numeric Aggregates: max
<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text;
class Program { static void Main(string[] args) { Random generator = new Random(0); int[] numbers = new int[1000]; for (int i = 0; i < 1000; i++) { numbers[i] = generator.Next(); } var queryResults = from n in numbers where n > 100 select n; Console.WriteLine("Max of Numbers > 100"); Console.WriteLine(queryResults.Max()); } }</source>
uses Max to get the length of the longest word in a string array.
<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {
public static void Main() { string[] words = { "cherry", "apple", "blueberry" }; int longestLength = words.Max(w => w.Length); Console.WriteLine("The longest word is {0} characters long.", longestLength); }
}</source>
Using Max to get the highest number in an integer array.
<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {
public static void Main() { int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; int maxNum = numbers.Max(); Console.WriteLine("The maximum number is {0}.", maxNum); }
}</source>