using System; using System.Linq; public class MainClass { public static void Main() { string[] numbers = { "0042", "010", "9", "2q7" }; int[] nums = numbers.Select(s => Int32.Parse(s)).ToArray(); } }
LINQ
uses select to create a sequence of each product name.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
public static void Main() {
List
var productNames =
from p in products
select p.ProductName;
foreach (var productName in productNames) {
Console.WriteLine(productName);
}
}
static List
List
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 });
return empTree;
}
}
class Product : IComparable
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
if (other == null)
return 1;
if (this.Id > other.Id)
return 1;
if (this.Id < other.Id) return -1; return 0; } } [/csharp]
Select with Anonymous Types: prints the name of every product in the product list along with the category of the product and its unit price
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
public static void Main() {
List
var productInfos =
from p in products
select new { p.ProductName, p.Category, Price = p.UnitPrice };
Console.WriteLine(“Product Info:”);
foreach (var productInfo in productInfos) {
Console.WriteLine(“{0} is in the category {1} and costs {2} per unit.”, productInfo.ProductName, productInfo.Category, productInfo.Price);
}
}
static List
List
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 });
return empTree;
}
}
class Product : IComparable
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
if (other == null)
return 1;
if (this.Id > other.Id)
return 1;
if (this.Id < other.Id) return -1; return 0; } } [/csharp]
Select with Anonymous Types: iterates over each element to print the element's name
using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass { public static void Main() { int[] numbers = { 5, 4, 1}; string[] strings = { "zero", "one", "two"}; var digitOddEvens = from n in numbers select new { Digit = strings[n], Even = (n % 2 == 0) }; foreach (var d in digitOddEvens) { Console.WriteLine("The digit {0} is {1}.", d.Digit, d.Even ? "even" : "odd"); } } }
Select with Anonymous Types: prints uppercase and lowercase versions of each string in an input array
using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass { public static void Main() { string[] words = { "Abc", "aBc", "AAA" }; var upperLowerWords = from w in words select new { Upper = w.ToUpper(), Lower = w.ToLower() }; foreach (var ul in upperLowerWords) { Console.WriteLine("Uppercase: {0}, Lowercase: {1}", ul.Upper, ul.Lower); } } }
Transformation: link two array.
using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass { public static void Main() { int[] numbers = { 5, 4, 1}; string[] strings = { "zero", "one", "two"}; var textNums = from n in numbers select strings[n]; Console.WriteLine("Number strings:"); foreach (var s in textNums) { Console.WriteLine(s); } } }
Use LINQ to query characters in a string
using System; using System.Collections.Generic; using System.Linq; static class TestString { static void Main() { var count = "abc 8" .Where(c => !Char.IsLetter(c)) .Count(); Console.WriteLine(count); } }