Lazy loading C#. Lazy initialization.

C# 4.0 introduced new class Lazy which provided for Lazy initialization. Lazy instantiation here means object is not created until it is get used first time. Primary use of Lazy initialization is performance improvements, reduce program memory requirements.Lazy provides thread safe object initialization.

Lasy<T> example to load object lazily

public partial class LazyClass : System.Web.UI.Page 
{
 private Lazy<List<string>> lazyItems = null; 
 public LazyClass() 
 { 
   lazyItems = new Lazy<List<string>>(GetItems); 
 } 
 public List<string> GetItems() 
 {
      List<string> items = new List<string>(); 
      for (int i = 0; i < 10; i++) 
       { 
          items.Add(string.Format("Item {0}", i)); 
       } return items;
 }

 public List<string> GetItemValues { get { return lazyItems.Value; } } 
}

So in above example we have defined private Lazy<List<string>> lazyItems = null; and then in constructor we have delegate the call to GetItems method which will return list of items. But here it will not generate and return list until we call "lazyItems.Value".

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Skip in Linq C#

Skip() in Linq avoids or skips the given number of elements from the sequence.

Skip() example in Linq

  protected void Page_Load(object sender, EventArgs e)
        {
            var numArr = new int[5];
            numArr[0] = 9;
            numArr[1] = 6;
            numArr[2] = 3;
            numArr[3] = 5;
            numArr[4] = 2;

            var numbers = numArr.Skip(3);
            foreach (var number in numbers)
            {
                Console.WriteLine(number);
            }

// Output will be 5, 2

So in above example of skip in linq, we have numArr.Skip(3);, that will skip first three elements from array and print remaining array elements.

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Take() in Linq C#

In Linq i.e. System.Linq, Take operator is used to get the first specified number of elements a sequence.

Linq Take() example

using System.Linq;
protected void Page_Load(object sender, EventArgs e)
        {
            var numArray = new int[5];
            numArray[0] = 95;
            numArray[1] = 66;
            numArray[2] = 3;
            numArray[3] = 54;
            numArray[4] = 2;


            var numbers = numArray.Take(3);
            foreach (var number in numbers)
            {
                Console.WriteLine(number);
            }
        }

//It will print 95, 66, 3.

So in above sample code of Take() we have numArray.Take(3) that means it will return us the sequence of first three elements from array.

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