Point of Interest

Point of Interest:

Msdn : " A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types.

MSDN "

The general rules for lambdas are as follows:

The lambda must contain the same number of parameters as the delegate type.

Each input parameter in the lambda must be implicitly convertible to its corresponding delegate parameter.

The return value of the lambda (if any) must be implicitly convertible to the delegate's return type.

Note that lambda expressions in themselves do not have a type because the common type system has no intrinsic concept of "lambda expression." However, it is sometimes convenient to speak informally of the "type" of a lambda expression. In these cases the type refers to the delegate type or Expression type to which the lambda expression is converted.

This Code Demonstrates an Anonymous Delegate

delegate void FunctionPointer(string str);
static void Main(string[] args)
{
FunctionPointer fp = delegate(string s)
{
Console.WriteLine(s);
Console.ReadLine();
};
fp("Hello World!");

In the example below, we are comparing Anonymous delegate with Lamda expression.

using delegate Anonymously : Func<string, string[]> funcRefofAMethod = delegate(string s) ....

using Func : Func<string,string[]> usingLamda = (s) => s.Split(spacer);

Step : 1 Create a web-site ( http://manas6/aspnet.35/mm.LINQFuncDelegate2/ )

Step: 2 Edit Codes

Class: FuncGeneric.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
//for IEnumerator and GetEnumerator();
using System.Collections;
/// <summary>
/// Summary description for FuncGeneric
/// </summary>
public class FuncGeneric
{
public string strProcess; public string str;
public FuncGeneric(){ str += "<br/>Constructor started"; }
public string StringProcessor(string title)
{
char [] spacer = new char[]{' '};
str += "<br/> Func<(Of <(T1, T2, TResult>)>)<font color='Teal'>";
str+="delegate with anonymous methods </font>";
// delegating a routine
Func<string, string[]> funcRefofAMethod = delegate(string s)
{
int i = s.Length;
char[] spacers = new char[] { ' ' };
return i > 0 ? s.Split(spacers, i) : s.Split(spacers);
};
str += "<br/>----->";
foreach (string word in funcRefofAMethod(title))
{
str += (word) + "&nbsp / ";
}
//alternate way
Func<string,string[]> usingLamda = (s) => s.Split(spacer);
//
str += "<br/> Using Lamda Expression <font color='red'>";
str+="(s) => s.Split(spacer);</font>";
str += "<br/>----->";
foreach(string word in usingLamda(title))
{
str += (word) + "&nbsp / ";
}
return str;
}

public static string[] UsingFunc(String param, int limit)
{
char[] spacers = new char[] { ' ' };
string[] str;
if (limit > 0)
{
str= param.Split(spacers, limit);
}
else
{
str = param.Split(spacers);
}
return str;
}
}

Default.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
protected string str;
protected void Page_Load(object sender, EventArgs e)
{
FuncGeneric fg = new FuncGeneric();
L1.Text += "----- Calling a Method in an external Class";
L1.Text += fg.StringProcessor("<br/>If it be love indeed, tell me how much");

}
}

Default.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>mm.LINQFuncDelegate2: Func Delegate and Lamda </title>
</head>
<body bgcolor="#cccccc">
<form id="form1" runat="server"
style="background-color: #FFFFCC; border: thick solid #800080; padding: 10px; margin: 10px; width: 500px">
<div>
<asp:Label ID="L1" runat="server" Text=""></asp:Label>
</div>
</form>
</body>
</html>

Step : 3 Runtime analysis

With debug

tying variable in watch window