Csharp/C Sharp/LINQ/LastOrDefault
Содержание
Call LastOrDefault returned from Take
<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.Take(0).LastOrDefault();
Console.WriteLine(name == null ? "NULL" : name);
}
}
</source>
LastOrDefault returns null when an Element Is Found
<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.LastOrDefault();
Console.WriteLine(name == null ? "NULL" : name);
}
}
</source>
LastOrDefault with string operator
<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.LastOrDefault(p => p.StartsWith("Z"));
Console.WriteLine(name == null ? "NULL" : name);
}
}
</source>
Use LastOrDefault
<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, 3, 5, 7, 9 };
var query = numbers.FirstOrDefault(n => n % 2 == 0);
Console.WriteLine("The first even element in the sequence");
Console.Write(query);
Console.WriteLine("The last odd element in the sequence");
query = numbers.LastOrDefault(n => n % 2 == 1);
Console.Write(query);
}
}
</source>
