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IS the complete defination for Polymorphism....?
Polymorphism:-
When child class inherits from a parent class and it gains all the method's properties of the parent class.
To resolve this problem a class member from a parent class, the parent class has to be declare as virtual while the child class should declare as override..
this whole process is called polymorphism
MUHAMMAD FAROOQ
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Somewhat, but you're bogged down in details of implementation.
MUHAMMAD FAROOQ1991 wrote: To resolve this problem
What problem?
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Try not to repost[^].
Too much of heaven can bring you underground
Heaven can always turn around
Too much of heaven, our life is all hell bound
Heaven, the kill that makes no sound
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An essential feature of polymorphism is that the child classes exhibit different behaviors than the parent and sibling classes. This is implied by the name, which means "many shapes" in Latin.
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I don't think that "child ... parent and sibling classes" is strictly a part of polymorphism (at least not since we got interfaces); in my opinion they're really just one implementation.
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Well, yes, but we no longer need a parent to define an interface (in some languages).
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The value of this arrangement is that the parent's interface is used by the users of these classes, so any child class can be substituted, and will provide different ("poly") behavior ("morphism").
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But we no longer require a parent/child relationship in order to have different ("poly") behavior ("morphism") -- now unrelated classes can be used.
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Well I think I would disagree with the statement of using Interfaces.
In the truest, textbook usage of polymorphism your are providing a different implementation of an existing implementation. While an Interface defines necessary methods/properties that must be implemented, and you can have various implementations of those methods, you don't have a base behaviour to fall back on.
So an example of Polymorphism would be a class that has a computation method that has been marked virtual.
In the base class it uses all of the various properties within the class to compute a value. In addition to this computation method are a number of setters/validators that ensure all the data is valid before you call the method. There may also be some security wrapped around everything and it has all been tested and proven functional.
You now need that class library to collect exactly the same data, and all validations, but you need to alter how the computation method behaves. So you inherit the base class and override the existing method to implement your behaviour.
In a few months you may have another use of the same base class and in that case you want the base computation to occur, but you need to return half the value. In that case, once again, you inherit the base class, override the method, call the base computation and then return the value returned by 2.
What you gain in the polymorphism model is all of the functionality of the base class that does NOT have to be tested (since it is already tested and working). All you have to test is your new computation code. Thus you gain functionality and minimize the testing needed to accomplish your goal.
Software Zen: delete this;
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Michael J. Eber wrote: textbook usage
An outdated textbook, yes.
Michael J. Eber wrote: method that has been marked virtual
That's just details of implementation and language.
Michael J. Eber wrote: inherit the base class, override the method, call the base computation
That's details, and the caller doesn't need to know what's going on inside the class -- encapsulation.
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In MSDN I found this for dll import used with PInvoke:
Kernel32.dll on Windows 7 and Windows Server 2008 R2;
Psapi.dll if PSAPI_VERSION=1 on Windows 7 and Windows Server 2008 R2;
Psapi.dll on Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000
So how do i do programaticly find PSAPI_VERSION? I already Can determent windows version. But i am missing from the List Windwos 2008 and R2. I am doing the folowing way:
public static EnumWinVer GetWindowsVersion()
{
OperatingSystem os = Environment.OSVersion;
Version vs = os.Version;
if (os.Platform == PlatformID.Win32Windows)
{
switch (vs.Minor)
{
case 0:
return EnumWinVer.Win95;
case 10:
if (vs.Revision.ToString() == "2222A")
return EnumWinVer.Win98SE;
else
return EnumWinVer.Win98;
case 90:
return EnumWinVer.WinME;
}
}
else if (os.Platform == PlatformID.Win32NT)
{
switch (vs.Major)
{
case 3:
return EnumWinVer.WinNT3_51;
case 4:
return EnumWinVer.WinNT4_0;
case 5:
if (vs.Minor == 0)
return EnumWinVer.Win2000;
else
return EnumWinVer.WinXP;
case 6:
if (vs.Minor == 0)
return EnumWinVer.WinVista;
else
return EnumWinVer.Win7;
default:
break;
}
}
return EnumWinVer.Undefined;
}
I am looking into GetModuleFileNameEx. QueryFullProcessImageName also can do the job. But minimum OS is Vista.
So what would happen when Dllimport calls function that doesn't exsist on current OS. So how do i handle that.
Thanks in advance for any answers to those question.
Have a nice day
edit:
[DllImport("kernel32.dll", EntryPoint = "GetModuleFileNameEx")]
static extern int K32GetModuleFileNameEx(IntPtr hProcess, IntPtr hModule, StringBuilder lpFilename, int nSize);
[DllImport("psapi.dll", EntryPoint = "GetModuleFileNameEx")]
static extern int PSAPIGetModuleFileNameEx(IntPtr hProcess, IntPtr hModule, StringBuilder lpFilename, int nSize);
After this i will Handle System.EntryPointNotFoundExpection.
Now i only need how to detect Windows version for Windows 2008.
modified on Sunday, September 4, 2011 6:02 AM
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Why are you using unmanaged code? It seems that Process.MainModule.FileName will get this information without worrying about this sort of thing (which is the entire purpose of using a framework like .Net in the first place).
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Because I am gonna use WriteProcessMemory and ReadProcessMemory. Those calls does not support in .NET. I am creating a Memory Scanner. My personal project for hobby. I am creating similar to CheatEngine. The second thing is I want to learn PInvoke, even if it is harder.
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Looks like you can get the parameters you need for Read/WriteProcessMemory (which is resident in one place) via Process.Handle and Process.MainModule.BaseAddress.
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Hi...I'm new in image processing and I have to recognize shapes from monochrome bitmap. I puled the matrix from image and now I have to create chain code for it. It has to be 8 directional. If someone has the finished code please send me or if not please give me some directions of how to create it myself. Thanks in advance.
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Thanks 
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hello guys... I have couple of IP cameras which I have managed to configure, and assigned them the IPs. But I dont know how to discover these IP cameras in some c# application.
Like, the form should show all the discoverable (available) ip cameras and when upon clicking a camera from the list, it should start showing the video from that camera.
What should be the first step? thnx
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Hi there,
I have another problem in my code,
this is my code :
private void SendEmail(MailMessage message, MailAddress from)
{
SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
smtpClient.EnableSsl = false;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = new NetworkCredential("someone@gmail.com", "password");
try
{
smtpClient.Send(message);
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
message.Dispose();
}
}
and now I have following exception in line "smtpClient.Send(message)" :
System.Net.Mail.SmtpException: Failure sending mail. ---> System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 209.85.143.108:587
at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)
--- End of inner exception stack trace ---
at System.Net.ServicePoint.GetConnection(PooledStream PooledStream, Object owner, Boolean async, IPAddress& address, Socket& abortSocket, Socket& abortSocket6, Int32 timeout)
at System.Net.PooledStream.Activate(Object owningObject, Boolean async, Int32 timeout, GeneralAsyncDelegate asyncCallback)
at System.Net.PooledStream.Activate(Object owningObject, GeneralAsyncDelegate asyncCallback)
at System.Net.ConnectionPool.GetConnection(Object owningObject, GeneralAsyncDelegate asyncCallback, Int32 creationTimeout)
at System.Net.Mail.SmtpConnection.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpTransport.GetConnection(ServicePoint servicePoint)
at System.Net.Mail.SmtpClient.GetConnection()
at System.Net.Mail.SmtpClient.Send(MailMessage message)
--- End of inner exception stack trace ---
at System.Net.Mail.SmtpClient.Send(MailMessage message)
at EmailSender.EmailSenderForm.SendEmail(MailMessage message, MailAddress from) in
is it from my code or my machine or my network or ...?
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Gmail requires EnableSsl = true
Its the man, not the machine - Chuck Yeager
If at first you don't succeed... get a better publicist
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I set EnableSsl = true but I have same exception
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I alreayd told you what the problem is. There's nothing wrong with your code. You've got a network problem that we cannot solve for you.
Your errors are telling you that the gmail network isn't reachable. That means you've got one or more firewalls blocking traffic to either gmail, or blocking anything on port 587, or you're got much larger network issues to deal with.
There is no code in the world that is going to get around that problem. You either have to have your network administrators fix this, or give up on getting this to work.
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