A lambda expression is an anonymous function
that you can use to create delegates or expression tree types. By using lambda
expressions, you can write local functions that can be passed as arguments or
returned as the value of function calls. Lambda expressions are particularly
helpful for writing LINQ query expressions. Lambda expression you can use in two
case one when you want to make tree business logic and second when you want
simplify code in delegate. In order to understand lambda function, just have
quick look of Delegate in C#.
What is delegate in C#?
A delegate in C# is similar to a function pointer in C or C++. Using a delegate
allows the programmer to encapsulate a reference to a method inside a delegate
object. The delegate object can then be passed to code which can call the
referenced method, without having to know at compile time which method will be
invoked. Unlike function pointers in C or C++, delegates are object-oriented,
type-safe, and secure.
Let's create a simple delegate that will called square function.
Code
using
System;
class
Example
{
delegate int
delPointer(int i);
static int Square(int
x)
{
return x * x;
}
static delPointer obj = Square;
//Delegate pointing to Square method..
public static
void Main()
{
//Invoking deleaget
int Result = obj(5);
Console.WriteLine("Square
:" + Result);
}
}
Output
![Image-1.jpg]()
Now let's simplify above code using lambda expression.
To create a lambda expression, you specify input parameters (if any) on the left
side of the lambda operator =>, and you put the expression or statement block on
the other side. For example, the lambda expression x => x * x specifies a
parameter that's named x and returns the value of x squared. You can assign this
expression to a delegate type, as the following example shows:
Code
using
System;
class
Example
{
delegate int
del(int i);
static void Main(string[]
args)
{
del myDelegate = x => x * x;
int j = myDelegate(5);
//j = 25
Console.WriteLine("Square:"
+ j);
}
}
Output
![Image-2.jpg]()