C# Delegates and Events logic and syntax issues

As my code suggests, I'm trying to create a delegate which will point to the StringBuff method BuffString, which creates a StringBuilder that is going to have a fair amount of settings, etc.

My problem is that, for some reason, no matter what it is I try I can't pass the reference to the StringBuff class I made within my Sprite class to the delegate's constructor without receiving an error. Ontop of that, I feel like creating an event may be useful to help initiate the delegate.

The main problem is that I'm just now barely grasping these two concepts, as well as how to use them as replacements for function pointers which are allowed in other programming languages.

If anyone has any idea on what it is I need to do to make this work, I would definitely appreciate it.

Here's the code:

public class StringBuff
        {
            private static StringBuilder stringBuffer = new StringBuilder();

            public static StringBuilder BuffString(string _string) //--may possibly have to use IntPtr to reference stringBuffer here. 
            //This is the equivalent to the "strbuff_new" C++ method variant, designed to update the stringBuffer.
            {
                int iCounter = 0;

                stringBuffer.Append(_string + " ");

                iCounter += _string.Length + 1;

                if (iCounter == stringBuffer.Capacity - 1)
                {
                    stringBuffer.Capacity += stringBuffer.Capacity; 
                }

                return stringBuffer;
            }
        }

        public delegate void UpdateStringBuffer(StringBuff sender);

        public class Sprite : SpriteInterface.ISprite
        {
            private StringBuff stringBuff = new StringBuff();

            public event UpdateStringBuffer stringBuffEvent
            {
                add
                {
                    Console.WriteLine("Adding");
                    stringBuffEvent += value;
                }
                remove
                {
                    Console.WriteLine("Removing...");
                    stringBuffEvent -= value;
                }
            }

            static void Main()
            { 
 开发者_如何学Go               new Sprite().stringBuffEvent += new UpdateStringBuffer(stringBuff);
            }




        }

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I believe you are in need for some reading. Refer to the following:

Events Tutorial

Introduction to Delegates and Events

Events and Delegates simplified

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You are misunderstanding the use of events and delegate.

When you want to add an Event Handler to an event, you pass a delegate of the same type as the event (which you did correctly)
But when you create a delegate, what you should pass in the constructor (most of the time) is a Method Name and not some variable, since a delegate is a kind of pointer to a (list of) functions.

I reccomend you to read more about delegates as Akram Shahda suggested but just for now i'll tell you that the method that you should pass as parameter to the delegate constructor should have the same signature - means return the same value and accept the same parameters. so for example you could have:

// This method have the same signature as UpdateStringBufferDelegate
public void SomeMethod (StringBuff buff)  
{
    // Doing somthing here
}

And then you can do in your main:

// Passing method's name and not a variable!!
new Sprite().stringBuffEvent += new UpdateStringBuffer(SomeMethod);

The Actuall parameters that will be passed to the function itself (some StringBuff) only determined at the time of the invokation of the event.
You should read more about that.

Good Luck!

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you are doing it wrong,

 new Sprite().stringBuffEvent += new UpdateStringBuffer(stringBuff);

Above code is invalid due to following reasons.

1. stringBuff that your UpdateStringBuffer is taking is an instance of StringBuff within Sprite.

2. You are accessing stringBuff from the static Main method which does not have any idea about stringBuff where it is located.

---

1- The delegate's constructor can only have a parameter Method. Ex

public delegate void UpdateStringBuffer(StringBuff sender);

2- You can declare ur event and add a method to define ur method in ur Splite class. Ex:

public event UpdateStringBuffer stringBuffEvent;

public ProcessUpdateStringBuffer(UpdateStringBuffer yourMethod)
{
       stringBuffEvent += yourMethod
}

3- and from ur main u can define ur method to the event and invoke it like this:

Sprite sprite = new Sprite();
sprite.ProcessUpdateStringBuffer(UpdateStringBuffer(urMethod));
sprite.stringBuffEvent(ur parameters);