C#-Specific Lambdas Operations

C#-Specific Lambdas Operations

As mentioned, C# lambda expressions currently offer more flexibility than their VB counterparts. The main reason
C# lambdas are more expressive is due to the fact that C# supports anonymous methods.

Specifically, VB lambdas have the following limitations. VB lambdas can only be used if the underlying delegate
points to functions, not subroutines. In other words, a Function statement must always have a return value.

Furthermore, VB lambdas can only process arguments via a single code statement. It is not possible to define a
collection of code statements to process lambda arguments in VB.

C# lambda expressions can specify a set of code statements that will be used to process incoming arguments.
Furthermore, the code statements do not need to return a value. Again, this is not currently possible in VB.

When your arguments are processed by multiple code statements, they are grouped within curly brackets to define
their scope. Consider the following code example. Notice you are using a lambda that uses a delegate prototyped to
return void and take a single string parameter. Also notice the code in bold is in fact an argument to the
PrintInReverse delegate constructor.

namespace LambdaExpressionsMultipleParams
{
public delegate void PrintInReverse(string msg);

class Program
{
  static void Main(string[] args)
  {
    Console.WriteLine("***** Lambdas with Multiple Code Statements! *****\n");

    // This lambda pushes a single arg to
    // a stack of code statements.
    PrintInReverse p = new PrintInReverse(msg => {
      Console.WriteLine("Message is: {0}", msg);
      char[] chars = msg.ToCharArray();
      Array.Reverse(chars);
      string strReverse = new string(chars);
      Console.WriteLine("Message reversed is: {0}", strReverse);
    });

    p("Hello World!");
    Console.ReadLine();
  }
}
}

To wrap up your look at lambdas, remember the following:
      •        They offer a concise way to interact with delegates.
      •        They break down into a set of arguments to process and an expression to process them.
      •        VB lambdas can only work with delegates pointing to functions, not subroutines.
      •        VB lambdas can only process arguments with a single code expression.

LINQ uses lambdas transparently in the background when you make use of LINQ query operators. However, more
complex LINQ queries may entail working with the lambda expressions directly. Be sure to consult the .NET
Framework 3.5 SDK documentation for further examples of lambda expression syntax.

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