C# [VB.net / C#] Events/Delegates example [SOURCE]

[C#] [VB.net / C#] Events/Delegates example [SOURCE] - Printable Version

+- Hack Forums (https://hackforums.net)
+-- Forum: Tech (https://hackforums.net/forumdisplay.php?fid=444)
+--- Forum: Coding (https://hackforums.net/forumdisplay.php?fid=151)
+---- Forum: Software Development (https://hackforums.net/forumdisplay.php?fid=118)
+---- Thread: [C#] [VB.net / C#] Events/Delegates example [SOURCE] (/showthread.php?tid=575989)

[VB.net / C#] Events/Delegates example [SOURCE] - Charny - Jul 29, 2010

Hello, I made a little events/delegates example. I did it because I was bored and I decided to make it :P. I'm sharing it with you because events and delegates can be hard when your learn them and this example could help you.

I know, there's better way to divide, but I needed a subject for the example. So I took the division.

C#
Spoiler (Click to View)

Visual Basic .NET
Spoiler (Click to View)

Division class (Division.cs)

Code 
Class Division

    Public Delegate Sub EventHandler(sender As [Object], e As DivisionEventArgs)

    'Delegate

    Public Event DivisionDone As EventHandler

    'This event will be executed when the divison will be done.

    Public Event DivisionPerZero As EventHandler

    'This event will be executed when the divisor is 0.

    Public Sub New()

        'Constructor

    End Sub

    Public Sub Divide(dividend As Integer, divisor As Integer)

        If divisor = 0 Then

            If DivisionPerZero IsNot Nothing Then

                RaiseEvent DivisionPerZero(Me, New DivisionEventArgs(dividend, divisor, 0.0))

                'Execute the DivisionPerZero event

                Return

            End If

        End If

        Dim num As Double = dividend \ divisor

        RaiseEvent DivisionDone(Me, New DivisionEventArgs(dividend, divisor, num))

        'Execute the DivisionDone event

    End Sub

End Class

Class DivisionEventArgs

    Inherits EventArgs

    'The arguments of the division.

    Public Sub New(a As Integer, b As Integer, r As Double)

        m_dividend = a

        m_divisor = b

        m_result = r

    End Sub

    Private m_dividend As Integer

    Private m_divisor As Integer

    Private m_result As Double

    Public ReadOnly Property Dividend() As Integer

        Get

            Return m_dividend

        End Get

    End Property

    Public ReadOnly Property Divisor() As Integer

        Get

            Return m_divisor

        End Get

    End Property

    Public ReadOnly Property Result() As Double

        Get

            Return m_result

        End Get

    End Property

End Class

And you can use it like that :

Code 
Private Sub TESTING_METHOD()

    Dim division As New Division()

    division.DivisionDone += New Division.EventHandler(AddressOf div_DivisionDone)

    division.DivisionPerZero += New Division.EventHandler(AddressOf div_DivisionPerZero)

    division.Divide(10, 5)

End Sub

Private Sub div_DivisionPerZero(sender As Object, e As DivisionEventArgs)

    MessageBox.Show("Error! Division per zero!")

End Sub

Private Sub div_DivisionDone(sender As Object, e As DivisionEventArgs)

    MessageBox.Show("Result : " + e.Result.ToString())

End Sub

Enjoy! If you have any questions, ask them here!

* - CometJack - Jul 29, 2010

That looks very confusing, can you comment a little please? Rated 5 stars :)

* - xhtmlphp™ - Jul 29, 2010

(Jul 29, 2010 08:01 PM)CometJack Wrote: That looks very confusing, can you comment a little please? Rated 5 stars :)

Ya, I think Charny should do an explanation on this :P

I don't understand Delegates, I've seen them being mentioned a few times but never understood the use of them :(

* - Charny - Jul 29, 2010

(Jul 29, 2010 08:26 PM)xhtmlphp Wrote: Ya, I think Charny should do an explanation on this :P

I don't understand Delegates, I've seen them being mentioned a few times but never understood the use of them :(

You can use delegates like that.. :

Code 
public delegate void Write(string str);

  private void writeString(string str)

  {

    MessageBox.Show(str);

  }

  private void writeLength(string str)

  {

    MessageBox.Show(str.Length.ToString());

  }

  private void TestDelegate()

  {

    Write write = new Write(writeString);

    write += new Write(writeLength);

    write("test");

  }

Try this code and check the result, then you can play with the code ;).

* - CometJack - Jul 29, 2010

I get the delegate's but I don't get how you make your own event handler :(

* - Charny - Jul 29, 2010

(Jul 29, 2010 08:41 PM)CometJack Wrote: I get the delegate's but I don't get how you make your own event handler :(

Read some events tutorials, you will learn it ;).

* - Charny - Jul 30, 2010

A little buump! 😁

* - enacje - Jul 30, 2010

this is hard to learn but harder to explain it :P I can make them but I can't explain how and what lol

* - Charny - Jul 30, 2010

(Jul 30, 2010 08:40 AM)enacje Wrote: this is hard to learn but harder to explain it :P I can make them but I can't explain how and what lol

Haha, same for me 😝. That's why I didn't really gave informations on them.

* - Charny - Aug 6, 2010

A little bump for my post :D!

* - laptopguy - Aug 7, 2010

Nice one Charny. People who call themselves programmers and don't understand this type of shit aren't tbh. And why was the thread allowed to die ? This is one of those things in this section that is actually useful, like the things Vorfin and Deathader post sometimes.

* - Charny - Aug 7, 2010

(Aug 7, 2010 12:14 PM)kRaeTwin Wrote: Nice one Charny. People who call themselves programmers and don't understand this type of shit aren't tbh. And why was the thread allowed to die ? This is one of those things in this section that is actually useful, like the things Vorfin and Deathader post sometimes.

Thanks, and why is this thread dieing? Because most 'coders' here doesn't bother learning delegates & events because their IDE does everything for them..

(Sorry if it didn't make sense <.<)

* - Charny - Aug 11, 2010

Bumppp! I'll do another example soon :).

* - killerdoob420 - Aug 11, 2010

very nice i couldnt have explained it better

* - Charny - Aug 11, 2010

(Aug 11, 2010 11:02 AM)killerdoob420 Wrote: very nice i couldnt have explained it better

Thanks for the comment 😁!