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// Invoke() is really called here!

Console.WriteLine("10 + 10 is {0}", b(10, 10));

Under the hood, the runtime actually calls the compiler-generated Invoke() method. You can

verify this fact for yourself if you open your assembly in ildasm.exe and investigate the CIL code

within the Main() method:

.method private hidebysig static void Main(string[] args) cil managed

{

...

callvirt instance int32 SimpleDelegate.BinaryOp::Invoke(int32, int32)

}

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Although C# does not require you to explicitly call Invoke() within your code base, you are free

to do so. Thus, the following code statement is permissible:

Console.WriteLine("10 + 10 is {0}", b.Invoke(10, 10));

Recall that .NET delegates are type safe. Therefore, if you attempt to pass a delegate a method

that does not “match the pattern,” you receive a compile-time error. To illustrate, assume the

SimpleMath class now defines an additional method named SquareNumber(), which takes a single

integer as input:

public class SimpleMath

{

...

public static int SquareNumber(int a)

{ return a * a; }

}

Given that the BinaryOp delegate can only point to methods that take two integers and return

an integer, the following code is illegal and will not compile: