Anonymous methods in C#.net :
Anonymous methods is a new language feature in C# 2.0, Anonymous methods
allow us to define a code block where a delegate object is acceptable. This
facility saves us an extra step of creating a delegate for small code blocks
that we want to pass to a delegate. It also removes the cluttering of small methods in the class code. Let us say, for
instance, that we have a
string
collection class named MyCollection. This class has a
method that retrieves all the items in the collection that satisfies a user
supplied criteria, i.e., the caller decides whether a particular item in the
collection qualifies for being retrieved as part of the return array from this
method.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
namespace AnonymousMethodsandDelegates
{
class Program
{
delegate int PointToAddFunction(int
num1, int num2);
static void Main(string[] args)
{
Stopwatch
objwatch = new Stopwatch();
for (int m = 0;m <
10; m++)
{
objwatch.Reset();
objwatch.Start();
for (int
l = 0; l < 1000; l++)
{
//another Method
PointToAddFunction p = delegate(int x, int y)
{
return
x + y;
};
int z = p.Invoke(23, 45);
}
objwatch.Stop();
Console.WriteLine(objwatch.ElapsedTicks.ToString());
}
Console.ReadLine();
}
static int Add(int num1, int num2)
{
return num1 + num2;
}
}
}
Output is : Recording
For Anony Methods(Elapsing Time)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
namespace AnonymousMethodsandDelegates
{
class Program
{
delegate int PointToAddFunction(int
num1, int num2);
static void Main(string[] args)
{
Stopwatch objwatch = new
Stopwatch();
for (int m = 0;m <
10; m++)
{
objwatch.Reset();
objwatch.Start();
for (int
l = 0; l < 1000; l++)
{
//another Method
PointToAddFunction p = Add;
int z = p.Invoke(23, 45);
}
objwatch.Stop();
Console.WriteLine(objwatch.ElapsedTicks.ToString());
}
Console.ReadLine();
}
static int Add(int num1, int num2)
{
return num1 + num2;
}
}
}
Recording for Named Delegates(Elapsing Time) :
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleLambda
{
class Program
{
delegate double CalArePointer(int
r);
static CalArePointer cpointer = CalculateArea;
static void Main(string[] args)
{
double area = cpointer.Invoke(23);
Console.WriteLine("Area
of the Circle is : " + area);
Console.ReadLine();
}
static double
CalculateArea(int r)
{
return 3.14 * r * r;
}
}
}
-------------------------xxxxxx
Or
xxxx----------------------------------------------
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleLambda
{
class Program
{
delegate double CalArePointer(int
r);
static void Main(string[] args)
{
CalArePointer cpointer = new
CalArePointer(delegate(int r)
{
return
3.14 * r * r;
}
);
double area = cpointer(20);
Console.WriteLine("Area
of the Circle is : " + area);
Console.ReadLine();
}
}
}
By using Lambda Expressions
:
CalArePointer cpointer = r => 3.14 * r *
r;
double area = cpointer(20);
Console.WriteLine("Area
of the Circle is : " + area);
Using Lambda
Expressions+Functions :
Func<double, double> cpointer = r => 3.14 * r * r;
double area = cpointer(20);
Console.WriteLine("Area
of the Circle is : " + area);
Using Action:
Action<string>
Myaction = y => Console.WriteLine(y);
Myaction("Welcome");
Using Predicates :
Predicate<string>
checkgreaterthan5 = x => x.Length > 5;
List<string>
ostring = new List<string>();
ostring.Add("Mohan");
ostring.Add("Venkat");
string str = ostring.Find(checkgreaterthan5);
Console.WriteLine(str);
Expression Trees :
Coding for
(23+56)-(40+20)
BinaryExpression b1 = Expression.MakeBinary(ExpressionType.Add,
Expression.Constant(23), Expression.Constant(56));
BinaryExpression b2 = Expression.MakeBinary(ExpressionType.Add,
Expression.Constant(40),
Expression.Constant(20));
BinaryExpression b3 = Expression.MakeBinary(ExpressionType.Subtract, b1, b2);
int result= Expression.Lambda<Func<int>>(b3).Compile()();
Console.WriteLine("Result
is : " + result);
