Re: StreamWriter - C# Discussion Boards

Re: combobox in datagrid

Christian Graus15-Apr-08 0:14

Christian Graus

15-Apr-08 0:14

I don't see any code that would make you feel that the data source should be edited ?

Christian Graus

Please read this if you don't understand the answer I've given you

"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )

Re: combobox in datagrid

sarilee15-Apr-08 0:48

sarilee

15-Apr-08 0:48

sorry i didnt get you?

A pencil icon appears in datagrid whenever we edit any of its column.This icon is not appearing after insertion of combobox or any other control.Hence a new row is not getting added to datagrid.I need to perform insertion of data in database using datagrid.

Re: combobox in datagrid

Christian Graus15-Apr-08 0:50

Christian Graus

15-Apr-08 0:50

sarilee wrote:
A pencil icon appears in datagrid whenever we edit any of its column.

This occurs in a gridview, if you happen to configure it to use such an icon. I didn't know a datagrid supported that behaviour at all.

sarilee wrote:
I need to perform insertion of data in database using datagrid.

OK - then you need to render the controls that will contain the data and write database code to store it. Sounds like you're half way there.

Re: combobox in datagrid

sarilee15-Apr-08 1:15

sarilee

15-Apr-08 1:15

i got a solution of my problem.
Thanks

templates in datagrid

sarilee14-Apr-08 23:45

sarilee

14-Apr-08 23:45

is it possible to implement item templates in datagrid in windows forms?

Re: templates in datagrid

Christian Graus14-Apr-08 23:53

Christian Graus

14-Apr-08 23:53

I don't believe so, the templates are borne of webforms using HTML to start with

StreamWriter

George_George14-Apr-08 23:44

George_George

14-Apr-08 23:44

Hello everyone,

For example, my class Foo wraps an object of StreamWriter, I must make Foo implements IDisposable and in the Dispose method of class Foo, invoke Dispose method of the StreamWriter object instance to release resource properly?

using System.IO;


public class Foo : IDisposable
{
    StreamWriter a;

    public Foo()
	{

	}

    public void Dispose
    {
        if (null != a)
        {
            a.Dispose();
        }
    }

}

thanks in advance,
George

Re: StreamWriter

N a v a n e e t h15-Apr-08 0:25

N a v a n e e t h

15-Apr-08 0:25

George_George wrote:
I must make Foo implements IDisposable and in the Dispose method of class Foo, invoke Dispose method of the StreamWriter object instance to release resource properly

Yes that's correct. But the pattern you used to implement IDisposable is not correct. You may check this[^] to get an idea for implementing the same.

If you are using StreamWriter instance only in a method, declare it inside the method and wrap it in a using block, hence you can avoid implementing IDisposable in class Foo.

All C# applications should call Application.Quit(); in the beginning to avoid any .NET problems.- Unclyclopedia

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Re: StreamWriter

George_George15-Apr-08 2:55

George_George

15-Apr-08 2:55

Thanks N a v a n e e t h,

I have read through the article, looks great and answered most of my questions. One question which is not answered is what is the relationship between Finalize method and destructor?

Finalize will call destructor or vice versa? Or no relationship? GC will call Finalize, but I am not sure whether GC will call destructor as well?

regards,
George

Re: StreamWriter

N a v a n e e t h15-Apr-08 20:36

N a v a n e e t h

15-Apr-08 20:36

George_George wrote:
what is the relationship between Finalize method and destructor?

As far as the CLR is concerned, in C# something looks like a destructor is finalize method. System.Object has a Finalize() method, but C# won't allow you to override this. In C#, destructor is called as finalize method. To make it more clear look at the below class which uses a destructor and check the IL generated code

class Program
{
    static void Main(string[] args)
    {
    }
    ~Program()
     {
        // clean resources
     }
}

//IL CODE

.class private auto ansi beforefieldinit Program
        extends [mscorlib]System.Object
    {
        .method public hidebysig specialname rtspecialname instance void .ctor() cil managed
        {
        }

        .method family hidebysig virtual instance void Finalize() cil managed
        {
        }

        .method private hidebysig static void Main(string[] args) cil managed
        {
            .entrypoint
        }

    }

In the IL code you can see the Finalize() method. So C# compiler converted destructor to this Finalize() method. This will be called by garbage collector.

Considering performance, implementing destructor is costly. GC will maintain a separate queue for items that need finalization. So you should implement the Dispose() pattern and clean all your resources. Also call GC.SuppressFinalize() from dispose which will suppress the finalization.

Hope things are clear now

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Re: StreamWriter

George_George16-Apr-08 0:05

George_George

16-Apr-08 0:05

Thanks N a v a n e e t h,

1.

Which tool are you using to check IL code?

2.

N a v a n e e t h wrote:
GC will maintain a separate queue for items that need finalization. So you should implement the Dispose() pattern and clean all your resources. Also call GC.SuppressFinalize() from dispose which will suppress the finalization.

I do not understand why using Dispose is faster than using GC Finalize? GC may have some smarter ways to treat all the to be finalized resources altogether? Smile | :)

regards,
George

Re: StreamWriter

N a v a n e e t h16-Apr-08 2:00

N a v a n e e t h

16-Apr-08 2:00

George_George wrote:
Which tool are you using to check IL code?

I use reflector[^]. It's a great tool

George_George wrote:
GC may have some smarter ways to treat all the to be finalized resources altogether?

Yes, GC is smart. But you can't predict when GC will collect the resources. So implementing your own disposal methods, you are ensuring that all the unmanaged resources are deallocated once you finish with particular object. You won't be waiting for GC to clear that. Also classes that have finalize method, GC need two cycles to reclaim the memory fully. So it's an overhead.

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Re: StreamWriter

George_George16-Apr-08 2:22

George_George

16-Apr-08 2:22

Thanks N a v a n e e t h,

I watched it is not a Microsoft tool. So, Microsoft does not provide a similar tool? Smile | :)

regards,
George

Re: StreamWriter

N a v a n e e t h16-Apr-08 3:01

N a v a n e e t h

16-Apr-08 3:01

Nope

. But it is written by a Microsoft employee. It's must tool for every .NET programmers toolbox.

PS : I like the way you ask questions. It's clear and up to the point. Keep it up. Smile | :)

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Re: StreamWriter

George_George16-Apr-08 3:42

George_George

16-Apr-08 3:42

Thanks for your help, N a v a n e e t h!

I am previously a C++/Java developer, and I am new to C#. Happy to learn from you, especially for what are not given by MSDN. Smile | :)

regards,
George

Re: StreamWriter

Gareth H15-Apr-08 0:26

Gareth H

15-Apr-08 0:26

George_George,

Yeah thats fine, but it might be better using the "using" syntax.

http://msdn2.microsoft.com/en-us/library/yh598w02(VS.80).aspx[^]

Regards,
Gareth.

Re: StreamWriter

George_George15-Apr-08 2:54

George_George

15-Apr-08 2:54

Thanks gareth111,

I have read through the article, looks great and answered most of my questions. One question which is not answered is what is the relationship between Finalize method and destructor?

Finalize will call destructor or vice versa? Or no relationship? GC will call Finalize, but I am not sure whether GC will call destructor as well?

regards,
George

How I can paly Video files with C# & DirextX?

Mohammad Dayyan14-Apr-08 23:43

Mohammad Dayyan

14-Apr-08 23:43

Hi guys.
I want to play video files (*.mpeg, *.avi, ...) in my application with C# and DirectX . but I do not know how I do it?
Can you help me ? thanks.

www.mds-soft.persianblog.ir

Re: How I can paly Video files with C# & DirextX?

Christian Graus14-Apr-08 23:54

Christian Graus

14-Apr-08 23:54

You use the windows media player control, or managed direct show ( which is in the platform SDK nowadays ) to play video files. A cursory search of the web would give you tons of samples

Re: How I can paly Video files with C# & DirextX?

Mohammad Dayyan15-Apr-08 10:36

Mohammad Dayyan

15-Apr-08 10:36

ok, thanks. Smile | :)

Only God

integer type in C#

George_George14-Apr-08 23:33

George_George

14-Apr-08 23:33

Hello everyone,

1.

C# has integer types, int, int32, int64 and long. In my understanding, int32 is always 32-bit, int64 and long are always 64-bit.

My understanding correct?

2.

How about int? Is it 32-bit or 64-bit or depends on how we build application (build as 32-bit? build as 64-bit or any CPU?)

thanks in advance,
George

Re: integer type in C#

N a v a n e e t h15-Apr-08 0:32

N a v a n e e t h

15-Apr-08 0:32

George_George wrote:
C# has integer types, int, int32, int64 and long. In my understanding, int32 is always 32-bit, int64 and long are always 64-bit.

Yes, Int32 represents a 32 bit signed integer, and int64 a 64 bit signed integer.

George_George wrote:
How about int? Is it 32-bit or 64-bit or depends on how we build application (build as 32-bit? build as 64-bit or any CPU?)

It represents 32bit by default.

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Re: integer type in C#

George_George15-Apr-08 2:56

George_George

15-Apr-08 2:56

Thanks N a v a n e e t h!

regards,
George

Re: integer type in C#

Gareth H15-Apr-08 0:34

Gareth H

15-Apr-08 0:34

George_George,

http://msdn2.microsoft.com/en-us/library/exx3b86w(VS.80).aspx[^]

Regards,
Gareth.

Re: integer type in C#

George_George15-Apr-08 2:56

George_George

15-Apr-08 2:56

Cool, your reply is clear, Gareth!

regards,
George

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