Csharp/C Sharp by API/System.Linq/Enumerable
Содержание
- 1 Enumerable.Aggregate
- 2 Enumerable.Average()
- 3 Enumerable.Cast
- 4 Enumerable.Count()
- 5 Enumerable.DefaultIfEmpty
- 6 Enumerable.Distinct()
- 7 Enumerable.ElementAt
- 8 Enumerable.ElementAtOrDefault
- 9 Enumerable.ElementsAfterSelf
- 10 Enumerable.Empty
- 11 Enumerable.First
- 12 Enumerable.OrderBy
- 13 Enumerable.Range
- 14 Enumerable.Repeat
- 15 Enumerable.Where
Enumerable.Aggregate
<source lang="csharp">
using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass {
public static void Main() {
int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
var query = numbers.Aggregate((a, b) => a * b);
}
}
</source>
Enumerable.Average()
<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 };
double averageNum = numbers.Average();
Console.WriteLine("The average number is {0}.", averageNum);
}
}
</source>
Enumerable.Cast
<source lang="csharp"> using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{
public static void Main(){
object[] doubles = {1.0, 2.0, 3.0};
IEnumerable<double> d = doubles.Cast<double>();
Console.Write(d);
}
}
</source>
Enumerable.Count()
<source lang="csharp"> 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);
}
}
</source>
Enumerable.DefaultIfEmpty
<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", "a", "H", "over", "Jack"};
string name =
presidents.Where(n => n.Equals("H")).DefaultIfEmpty("Missing").First(); Console.WriteLine(name);
}
}
</source>
Enumerable.Distinct()
<source lang="csharp"> using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{
public static void Main(){
int[] numbers = {1, 1, 2, 3, 3};
Console.Write(numbers.Distinct());
}
}
</source>
Enumerable.ElementAt
<source lang="csharp"> using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{
public static void Main(){
int[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};
var query = numbers.ElementAt(4);
Console.Write(query);
}
}
</source>
Enumerable.ElementAtOrDefault
<source lang="csharp"> using System; using System.Collections; using System.Collections.Generic; using System.Text; using System.Linq; public class MainClass{
public static void Main(){
int[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};
var query = numbers.ElementAtOrDefault(9);
Console.Write(query);
}
}
</source>
Enumerable.ElementsAfterSelf
<source lang="csharp">
using System; using System.Linq; using System.Collections; using System.Collections.Generic; using System.Xml; using System.Xml.Linq; public class MainClass {
public static void Main() {
XElement firstParticipant;
XDocument xDocument = new XDocument(
new XDeclaration("1.0", "UTF-8", "yes"),
new XDocumentType("Books", null, "Books.dtd", null),
new XProcessingInstruction("Book", "out-of-print"),
new XElement("Books",
new XComment("Begin Of List"), firstParticipant =
new XElement("Book",
new XAttribute("type", "Author"),
new XElement("FirstName", "J"),
new XElement("LastName", "R")),
new XElement("Book",
new XAttribute("type", "Author"),
new XElement("FirstName", "E"),
new XElement("LastName", "B")),
new XComment("End Of List")));
foreach (XNode node in firstParticipant.ElementsAfterSelf()) {
Console.WriteLine(node);
}
}
}
</source>
Enumerable.Empty
<source lang="csharp"> using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {
public static void Main() {
IEnumerable<string> strings = Enumerable.Empty<string>();
foreach (string s in strings)
Console.WriteLine(s); Console.WriteLine(strings.Count());
}
}
</source>
Enumerable.First
<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", "a", "H", "over", "Jack"};
string jones = presidents.Where(n => n.Equals("H")).First();
if (jones != null)
Console.WriteLine("H was found");
else
Console.WriteLine("H was not found");
}
}
</source>
Enumerable.OrderBy
<source lang="csharp"> using System; using System.Linq; static class TestArray {
static void Main() {
Object[] array = { "String", 12, true, "a" };
var types =
array
.Select(item => item.GetType().Name)
.OrderBy(type => type);
}
}
</source>
Enumerable.Range
<source lang="csharp"> using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {
public static void Main() {
var numbers =
from n in Enumerable.Range(100, 50)
select new { Number = n, OddEven = n % 2 == 1 ? "odd" : "even" };
foreach (var n in numbers) {
Console.WriteLine("The number {0} is {1}.", n.Number, n.OddEven);
}
}
}
</source>
Enumerable.Repeat
<source lang="csharp"> using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {
public static void Main() {
var numbers = Enumerable.Repeat(7, 10);
foreach (var n in numbers) {
Console.WriteLine(n);
}
}
}
</source>
Enumerable.Where
<source lang="csharp"> using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {
public static void Main() {
string[] strings = { "one", "two", null, "three" };
Console.WriteLine("Before Where() is called.");
IEnumerable<string> ieStrings = strings.Where(s => s.Length == 3);
Console.WriteLine("After Where() is called.");
foreach (string s in ieStrings) {
Console.WriteLine("Processing " + s);
}
}
}
</source>
