.NET (Core and Framework)

Dave Kreskowiak25-Jun-07 10:02

Dave Kreskowiak

25-Jun-07 10:02

The only resource I know of is experience, or the tried and true technique of "trial and error".

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

Paul Conrad25-Jun-07 15:06

Paul Conrad

25-Jun-07 15:06

Dave Kreskowiak wrote:
The only resource I know of is experience, or the tried and true technique of "trial and error".

Know that feeling :->

Giorgi Dalakishvili25-Jun-07 20:37

Giorgi Dalakishvili

25-Jun-07 20:37

Dave Kreskowiak wrote:
The only resource I know of is experience, or the tried and true technique of "trial and error".

So you say that there is not any article in the internet on that subject?

#region signature
my articles
#endregion

originSH25-Jun-07 22:19

originSH

25-Jun-07 22:19

He's saying he doesn't know of one.

Doing a search on google returns lots of results but I don't know if any of them are any good:

http://www.google.co.uk/search?hl=en&q=c%23+memory+leaks&meta=[^]

Dave Kreskowiak26-Jun-07 2:42

Dave Kreskowiak

26-Jun-07 2:42

originSH wrote:
He's saying he doesn't know of one.

Thank you!

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007

How to build a IP LAN Scanner in .Net

originSH26-Jun-07 2:44

originSH

26-Jun-07 2:44

Carmine_XX25-Jun-07 4:49

Carmine_XX

25-Jun-07 4:49

Hello,
How can I build a IP lan scanner in .net(vb.net/c#)?
It should give the list of all computers/devices in the network, and their relative IPs and (eventually) MAC Address and device/computer name.
Thanks in advance, Wink | ;)

Carmine,
Webmaster of: www.thetotalsite.it
My web blog: blog.thetotalsite.it

Re: How to build a IP LAN Scanner in .Net

Ilya Verbitskiy8-Jul-07 1:18

Ilya Verbitskiy

8-Jul-07 1:18

http://www.codeproject.com/cs/internet/host_info_within_network.asp?df=100&forumid=146669&exp=0&select=1498979

Re: How to build a IP LAN Scanner in .Net

Carmine_XX8-Jul-07 4:41

Carmine_XX

8-Jul-07 4:41

Mhm but that program displays only PCs based on Windows.
Is there a way to display all network devices? (network printers, routers, PCs with Linux/MAC etc.)?

Carmine,
Webmaster of: www.thetotalsite.it
My web blog: blog.thetotalsite.it

Re: How to build a IP LAN Scanner in .Net

Ilya Verbitskiy8-Jul-07 21:19

Ilya Verbitskiy

8-Jul-07 21:19

You can use System.Net.NetworkInformation.Ping[^] to ping, is machine a live, after that you can use System.Net.Dns[^] to retrieve host name.

Generics, Inheritance and frustration

Santiago Perez25-Jun-07 2:38

25-Jun-07 2:38

I have a slightly different problem, I have a generic function that handles populating all the properties of a class and all it's inhreited class objecs. Such as this:

public static List<iperson> TGeneratePersonList(IDataReader oDR, ePersonType PersonType)
{
ArrayList oCols = Field.GetColumnNames(oDR);
oCols = Utilities.Field.GetColumnNames(oDR);
iPerson oP = null;
List<iperson> oPList = new List<iperson>();
while (oDR.Read())
{
switch (PersonType)
{
case ePersonType.Basic:
oP = new Person();
break;
case ePersonType.Contract_Person:
oP = new Contract_Person();
((Contract_Person)oP).Contract_Person_ID = Field.GetInt(oDR, "Contact_ID");
break;
case ePersonType.Vendor_Person:
oP = new Vendor_Person();
break;
}
oPList.add(oP);
}
return oPList;
}

THe problem is when I try to assign this result to a property of an object deined as :
public List<vendor_person> Personnel_List
{
get
{
if (this._Personnel_List == null)
this._Personnel_List = new List<vendor_person>();
return this._Personnel_List;
}
set
{
this._Personnel_List = value;
}

}

I get this at compile time:
Error 4 Cannot implicitly convert type 'System.Collections.Generic.List<projectcentral.contacts.iperson>' to 'System.Collections.Generic.List<projectcentral.contacts.vendor_person>' C:\Projects\ProjectCentral\ProjectCentral.Vendors\GenericVendor.cs 281 39 ProjectCentral.Vendors

Any ideas? It's rather urgent since I've been fighting with this for days and my job is on the line.

THanls;

Andy L 225-Jun-07 7:10

Andy L 2

25-Jun-07 7:10

You need to pre-define the type for the generic List class to the type of the object that will be populating it i.e. iPerson so assuming classes Person, Contract_Person and Vendor_Person are all derived from iPerson your code needs to change to the following:

public static List<iPerson> TGeneratePersonList(IDataReader oDR, ePersonType PersonType)
{
...

iPerson oP = null;
List<iPerson> oPList = new List<iPerson>();

...
}

and your property to:

public List<iPerson> Personnel_List
{
...
}

and the field _Personnel_List to:

private List<iPerson> _Personnel_List;

Incidentally, the TGeneratePersonList() is not a generic method - it is an ordinary method that returns a generic List of type iPerson.

This is a generic method:
public void GenericMethod<T>() // Where type T is defined when the method is called
{
// Do something with T in here
}

example calls

GenericMethod<int>();
GenericMethod<string>();
GenericMethod<MyClass>();

Santiago Perez25-Jun-07 8:32

25-Jun-07 8:32

With this scenario I would have to cast property Personnel_List everytime I need to get a property value from one of the derived objects. Doesn't this defeat the purpose of Generics? I guess I'm trying find the most efficient and scalable way to do this.

I tried a different approach as follows. I can't seem to find a way to have the Base class properties populated without having to re-wite the property assignment code in the derived classes.
Anyone encountered this before?

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
B objB = new B();
List oBList = new List();
objB.GenerateList(ref oBList);

}
}

public interface iClass
{
string Full_Name
{
get;
set;
}

string Short_Name
{
get;
set;
}
}

public class A : iClass
{
private string _PhoneA = "";
private string _Full_Name = "";
private string _Short_Name = "";

public string PhoneA
{
get { return _PhoneA; }
set { _PhoneA = value; }
}

public string Full_Name
{
get { return _Full_Name; }
set { _Full_Name = value; }
}
public string Short_Name
{
get { return _Short_Name; }
set { _Short_Name = value; }
}

public virtual void GenerateList(ref List List)
{
A objA = new A();
objA.Full_Name = "Tom";
List.Add(objA);

objA = new A();
objA.Full_Name = "Bob";
List.Add(objA);

objA = new A();
objA.Full_Name = "Gerry";
List.Add(objA);

}

}

class B : A, iClass
{
private string _SSN = "";

public string SSN
{
get { return _SSN; }
set { _SSN = value; }
}

public new void GenerateList(ref List List)
{
base.GenerateList(ref List);

foreach (B oB in List)
{
oB.SSN = "123";
}

}
}
}

Andy L 226-Jun-07 0:16

Andy L 2

26-Jun-07 0:16

Maybe I am missing the point somewhere but I cannot see why you need to use generics to do this.

In my previous example by placing all the initialisation properties into iPerson for example would enable you to initialise all classes derived from iPerson i.e.

// Interface that defines properties and methods to be called during initilaisation
public interface I
{
string Prop1 { get; set; }
int Prop2 { get; set; }
void Initialise(params object[] arrParams);
}

// Classes to be initialised
class A: I
{
private string _prop1 = null;
private int _prop2;

// Interface implementations
string I.Prop1
{
get { return _prop1; }
set { _prop1 = value; }
}

int I.Prop2
{
get { return _prop2; }
set { _prop2 = value; }
}

void I.Initialise(params object[] arrParams)
{
// Do some initialisation on params
Initialise(arrParams);
}

// Option for in class initialisation - could use virtual.
protected abstract void Initialise(params object[] arrParams);
}

class B: A
{
protected override void Initialise(params object[] arrParams)
{
}
}

class C: B
{
private string Prop3 = null;

protected override void Initialise(params object[] arrParams)
{
}
}

Now using interface I to initialise instances of A, B or C as follows:
//Create list
List<I> items = new List<I>();

// This could equally be:
// ArrayList items = new ArrayList();
....
if (ClassType == eType.A)
{
items.Add(new A());
}
else if (ClassType == eType.B)
{
items.Add(new B());
}
else if (ClassType == eType.C)
{
items.Add(new C());
}

// Initialisation can be performed on object instances of type A, B and C this way using interface I no casting required.
foreach (I item in items)
{
// Initialise object properties
item.Prop1 = source.P1;
item.Prop2 = source.P2;

//Or even call an initialise method on the object itself.
item.Initialise(source.P1, source.P2, "P3");
}

This example relies on a single interface structure defined at compile time, this is also a requirement that applies to generics - if what you are looking for is to try and initialise objects by examining their structures at run-time then this falls into the realms of Reflection - and only do this if for some reason you really need to.

If you are requiring to initialise properties that apply to the derived classes (i.e class C)
you could used the Initialise() method shown but you would have to either apply strict parameter ordering or employ a mechanism for identifying which parameter goes to which property.

Santiago Perez26-Jun-07 16:41

26-Jun-07 16:41

Sorry man, you went out to left field and away from the topic at hand. Thanks for your help anyway.

Santiago Perez26-Jun-07 18:28

26-Jun-07 18:28

Ok, I apologize again. Just having a frustrating day. I think I follow what you were trying to explain. I've also watched the webcast from Juval Lowy. What I was trying to explain in my previous post is that I got my function (not a method) to return a generic list of an interface that all my classes implement. What I don't quite understand is how I use this list in the referencing call if I'm expecting a List of of a specific type that implements that interface. Basically it looks to me like I have to iterate throuh the list and cast each object to my desired type in order to get the intelisense etc. Are you saying that I should have my function call look like this based on my last example? If so this won't compile because I get the following error on each result.Add()

Error 1 The best overloaded method match for 'System.Collections.Generic.List<t>.Add(T)' has some invalid arguments C:\Projects\ConsoleApplication1\ConsoleApplication1\Program.cs 95 17 ConsoleApplication1
Error 2 Argument '1': cannot convert from 'ConsoleApplication1.A' to 'T' C:\Projects\ConsoleApplication1\ConsoleApplication1\Program.cs 95 28 ConsoleApplication1

public static List<t> GetList<t>() where T : A,iClass
{
List<t> result = new List<t>();
iClass oC = null;
if (typeof(T) == typeof(A))
{
oC = new A();
((A)oC).Full_Name = "A_Tom";
result.Add((A)oC);

oC = new A();
((A)oC).Full_Name = "A_Bill";
result.Add((A)oC);

oC = new A();
((A)oC).Full_Name = "A_Jack";
result.Add((A)oC);

}
else if (typeof(T) == typeof(B))
{
oC = new B();
((B)oC).Full_Name = "b_Tom";
result.Add((B)oC);

oC = new B();
((B)oC).Full_Name = "B_Bill";
result.Add((B)oC);

oC = new B();
((B)oC).Full_Name = "B_Jack";
result.Add((B)oC);
}
return result;
}

Santiago Perez26-Jun-07 20:19