LINQ C# Book


            OfType accepts a nongeneric IEnumerable collection and emit a generic IEnumerable sequence that you can subsequently query: 
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
class Program
{
 static void Main()
 {
 ArrayList classicList = new ArrayList(); // in System.Collections 
 classicList.AddRange(new int[] { 3, 4, 5 });
 IEnumerable sequence1 = classicList.OfType();
 foreach (int i in sequence1)
 {
 Console.WriteLine(i);
 }
 }
}
 
The output:
3
4
5
When encountering an incompatible type OfType ignores the incompatible element.
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
class Program
{
 static void Main()
 {
 ArrayList classicList = new ArrayList(); // in System.Collections 
 classicList.AddRange(new int[] { 3, 4, 5 });
 IEnumerable sequence1 = classicList.Cast();
 foreach (int i in sequence1)
 {
 Console.WriteLine(i);
 }
 DateTime offender = DateTime.Now;
 classicList.Add(offender);
 sequence1 = classicList.OfType(); // OK - ignores offending DateTime 
 foreach (int i in sequence1)
 {
 Console.WriteLine(i);
 }
 }
}
 
The output:
3
4
5
3
4
5