The program defines three delegate types: voidDelegate, voidDelegateWithParam, and voidDelegateWithParamOrReturn. These delegate types represent references to methods with a particular parameter list and return type.
The voidDelegate delegate type represents a method with no parameters and no return value. The voidDelegateWithParam delegate type represents a method with a single string parameter and no return value. The voidDelegateWithParamOrReturn delegate type represents a method with a single string parameter and a string return value.
The Main() method of the Progam class creates three delegate instances, one for each delegate type. The delegate instances are then passed to the ExecuteDelegate(), ExecuteDelegateWithParam(), and ExecuteDelegateWithParamOrReturn() methods of the MyDelegates class. These methods invoke the corresponding methods that are referenced by the delegate instances.
For example, the following code creates a delegate instance for the voidDelegate delegate type and passes it to the ExecuteDelegate() method:
Code snippet
using static Program;
public class Program
{
public delegate void voidDelegate();
public delegate void voidDelegateWithParam(string msg);
public delegate string voidDelegateWithParamOrReturn(string msg);
public static void Main(string[] args)
{
//Delegate use case 1
voidDelegate voidDelegateObj = ShowMessage;
voidDelegateObj += ShowMessage2;
MyDelegates.ExecuteDelegate(voidDelegateObj);
//Delegate use case 2
voidDelegateWithParam voidDelegateWithParamObj = ShowMessageWithParam;
MyDelegates.ExecuteDelegateWithParam(voidDelegateWithParamObj, "This is voidDelegateWithParam Executed.");
//Delegate use case 3
voidDelegateWithParamOrReturn voidDelegateWithParamOrReturnObj = ShowMessageWithParamOrReturn;
Console.WriteLine("Return:"+MyDelegates.ExecuteDelegateWithParamOrReturn(voidDelegateWithParamOrReturnObj, "This is voidDelegateWithParamOrReturn Executed."));
}
private static void ShowMessage()
{
Console.WriteLine("This is voidDelegate Executed.");
}
private static void ShowMessage2()
{
Console.WriteLine("This is voidDelegate Executed. 2");
}
private static void ShowMessageWithParam(string msg)
{
Console.WriteLine(msg);
}
private static string ShowMessageWithParamOrReturn(string msg)
{
return msg;
}
}
public class MyDelegates
{
public static void ExecuteDelegate(voidDelegate voidDelegate)
{
voidDelegate();
}
public static void ExecuteDelegateWithParam(voidDelegateWithParam voidDelegate, string msg)
{
voidDelegate(msg);
}
public static string ExecuteDelegateWithParamOrReturn(voidDelegateWithParamOrReturn voidDelegate, string msg)
{
return voidDelegate(msg);
}
}
This code will invoke the ShowMessage() method, which prints the following message to the console:
Code snippet
This is voidDelegate Executed.
The other two delegate types are used in a similar way. The voidDelegateWithParam delegate type is used to pass a string parameter to the ShowMessageWithParam() method, and the voidDelegateWithParamOrReturn delegate type is used to pass a string parameter to the ShowMessageWithParamOrReturn() method and return the result as a string.
The program also prints the result of the ShowMessageWithParamOrReturn() method to the console. The result of the ShowMessageWithParamOrReturn() method is the string that was passed to it as a parameter.Here are some additional scenarios where delegates can be used in C#:
Asynchronous programming: Delegates can be used to implement asynchronous methods in C#. This allows code to run in the background without blocking the main thread.
Testing: Delegates can be used to test code in C#. This allows code to be tested without having to run the actual code.
Debugging: Delegates can be used to debug code in C#. This allows the behavior of code to be traced and analyzed.
Source Code:https://github.com/sunnisagar/Delegates/tree/master
I hope this explanation is helpful. Please let me know if you have any other questions.