Re: A perfect example where goto should be used - C# Discussion Boards

Re: Exception Handling - back into method

Colin Angus Mackay4-Mar-05 2:03

4-Mar-05 2:03

Seraphin wrote:
application should continue code processing in the try block

Make your try blocks smaller.

So if you have

try
{
    // Do item 1
    // Do item 2
    // Do item 3
}
catch(Exception ex)
{
    // Handle the exception
}

Change it to:

try
{
    // Do item 1
}
catch(Exception ex)
{
    // Handle the exception
}
try
{
    // Do item 2
}
catch(Exception ex)
{
    // Handle the exception
}
try
{
    // Do item 3
}
catch(Exception ex)
{
    // Handle the exception
}

Or a better solution would be to refactor your code so that item 1, item 2 and item 3 individual private methods that get called, each of which has their own try/catch block.

Does this help?

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A perfect example where goto should be used

leppie4-Mar-05 5:19

leppie

4-Mar-05 5:19

RESTART:
try
{
... some code ...
Exception appears here
}
catch(Exception ex)
{
... some code ...
  goto RESTART;
}

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Re: A perfect example where goto should be used

Dave Kreskowiak4-Mar-05 7:28

Dave Kreskowiak

4-Mar-05 7:28

A perfect example of when/why goto should NEVER be used! I haven't used GOTO since, what, 1992?

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Re: A perfect example where goto should be used

turbochimp4-Mar-05 11:13

turbochimp

4-Mar-05 11:13

Wow. I can't believe you would seriously suggest someone use this. Part of the advantage of methods written in a language like C, C++ or C# is that they are by nature "fall-through". No artificial flow interruptions, reroutes, twists, turns or gyrations are advised (such as "goto", "gosub" etc.).

This kind of coding reflects poor planning, not good practice. It looks like a (bad) piece of VB 6 code.

The most exciting phrase to hear in science, the one that heralds the most discoveries, is not 'Eureka!' ('I found it!') but 'That's funny...’

Re: A perfect example where goto should be used

Rob Graham4-Mar-05 11:39

Rob Graham

4-Mar-05 11:39

Maybe you should use IlDecompiler and look at the IL generated from some of your nice 'fall through' c# code. I think you'll find it is liberally sprinkled with goto's. The closer you get to the machine, the more useful and sensible goto gets to be.
what is gosub other than a void method call? is goto really any different than

if(true)<br />
  ...<br />
else<br />
  ...

I would agree that if-else is preferable for clatity: the brace blocks are clearer than a lable, but the result is no different: code branches to a new location under some conditions.

In leppies example, if there were multiple try-catch blocks in the same function, a goto and a common cleanup code block would be preferable for maintainability to repeating the code in each catch block...

Anger is the most impotent of passions. It effects nothing it goes about, and hurts the one who is possessed by it more than the one against whom it is directed.
Carl Sandburg

Re: A perfect example where goto should be used

turbochimp5-Mar-05 6:10

turbochimp

5-Mar-05 6:10

I was commenting on the code example provided. In the example, if an error is generated after the RESTART label, the code will loop indefinitely. That, to me, was a perfect example of why not to use the goto. It leads to bad code.

I'm not disputing whether IL contains goto calls. I am contending that at the time the IL is compiled, there are no nonsensical looping calls made if the developer has constrained him/herself to using the fall-through code style.

The most exciting phrase to hear in science, the one that heralds the most discoveries, is not 'Eureka!' ('I found it!') but 'That's funny...’

Re: A perfect example where goto should be used

leppie4-Mar-05 11:49

leppie

4-Mar-05 11:49

turbochimp wrote:
This kind of coding reflects poor planning, not good practice.

I beg to differ. Show me more readable code, sure you wrap a while around it, or some other way. The fact is goto is clean and simple, and it gives you much better flow control that you can perform via a for/while/etc.

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Re: A perfect example where goto should be used

Dave Kreskowiak4-Mar-05 16:08

Dave Kreskowiak

4-Mar-05 16:08

Until you find a sub with about 20-30 of them in it, then it's just damn ugly and completely unreadable.

Much better flow control? I'd say much more "quick and dirty" flow control. Seriously, I haven't used a single Goto in the last 13 years...

Sure, if you get down to the IL that the compiler generates, yes, you'll find Goto's, or more acurately, Jump's, all over the place. This will happen in lower level languages, but in higher level languages, C# or VB.NET or whatever, using Goto's is an extinct practice, found only in the code of 1st year students.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Re: A perfect example where goto should be used

Rob Graham4-Mar-05 17:05

Rob Graham

4-Mar-05 17:05

I am inclined to agree with you, since I can't recall needing to use a Goto in a very long time (other than in VB6 of course, where it is mandated by the crude error handling). Goto is rather the flow control of last resort, and will stay around in even high level languages for that last ditch "damn, now what?" situation that once in a very rare while crops up in even the best designed code...

Anger is the most impotent of passions. It effects nothing it goes about, and hurts the one who is possessed by it more than the one against whom it is directed.
Carl Sandburg

Re: A perfect example where goto should be used

turbochimp5-Mar-05 6:12

turbochimp

5-Mar-05 6:12

Um...okay...

The most exciting phrase to hear in science, the one that heralds the most discoveries, is not 'Eureka!' ('I found it!') but 'That's funny...’

C# / Oracle -->Getting ByteArray from field(VARCHAR(250)

Anonymous4-Mar-05 1:03

Anonymous

4-Mar-05 1:03

Hi All,

i have got a problem by getting data from an oracle column. The column contains 250 binary values in a single column ( VARCHAR2(250) )!
Each tries to get the byte to a byte array or into a string where not successful!

Just with object I could read something, just one letter and at least its wrong I think.

Thats my Source Code, ...
public static void Main(string[] args)
{
string constr = "Provider=msdaora; Data Source=***; USER ID=***; Password=***";
OleDbConnection myConnection = new OleDbConnection(constr);

string qry = "SELECT * FROM ruest_teach WHERE RT_RK_MODELL_NR= 'W202 M753 13' AND RT_RK_ORGE_NR = 591";

OleDbCommand myCommand = new OleDbCommand(qry,myConnection);
myConnection.Open();

//*** SELECT Operation ausführen lassen
OleDbDataReader myReader = myCommand.ExecuteReader();
string b = "";
int a = 0;
object c = new object();
while (myReader.Read())
{
a = Convert.ToInt32(myReader.GetDouble(0));
b = myReader.GetString(1);
c = myReader.GetOrdinal("RT_TEACH_H");
}
Console.WriteLine(a + " , " + b + " , |" + c + "|");
}

Maybe someone here can help me with my problem. It is really important, because it is part of my examination to get a programmers license in germany.

regards,
eXi

CE MAPI problem

ppp0013-Mar-05 23:45

ppp001

3-Mar-05 23:45

Hi all,

I try to using c# and programming the CEMAPI(by using VC++) in pocket pc 2003 to retrieve
the emails from the pocket pc. But after several days trials, I still
can't get the receipent and the body of the emails(I can only retrieve
the subject of the emails). Do anyone have the same experience as me ? I
just wonder there are system bugs in the pocket pc MAPI.

Thanks

Path to executable for a service

MBAndersen3-Mar-05 23:05

MBAndersen

3-Mar-05 23:05

I want to get the path to the executable file of a service
(from another app) via the servicecontroller class.
This will enable me to find the config file of the service
and modify this from another app.

How do I do that?

want code for add,del,update to db (c#)

chandtec3-Mar-05 22:56

chandtec

3-Mar-05 22:56

Hai ,

Iam having following fields.

name
exp
dob
primary
sec skills
ph
email
passport
location

i wnt these things to be added to my db

i wnt add btn , del btn , update btn

sql server , c#

KINDLY SEND ME

chand

Re: want code for add,del,update to db (c#)

Sebastian Schneider3-Mar-05 22:59

Sebastian Schneider

3-Mar-05 22:59

Yikes.

Try googling for "SQL", "ADO", "ODBC". In that order.

And stop shouting.

Cheers
Sid

Re: want code for add,del,update to db (c#)

Colin Angus Mackay3-Mar-05 23:24

Colin Angus Mackay

3-Mar-05 23:24

Why ODBC? There is a Sql Server Data Provider built in to the .NET Framework in the System.Data.SqlClient namespace.

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Re: want code for add,del,update to db (c#)

Sebastian Schneider3-Mar-05 23:27

Sebastian Schneider

3-Mar-05 23:27

I totally missed the fact that he might actually mean the "MS SQLServer" Smile | :)

I thought he was referring to "a SQL Server" (in general) Big Grin | :-D

Cheers
Sid

Re: want code for add,del,update to db (c#)

J4amieC4-Mar-05 0:14

J4amieC

4-Mar-05 0:14

You have been posting this (and similar) questions every few hours for the past few days, you have not recieved any meaningful replies - does this not tell you anything?

Here, let me give you some pointers.

1) It is understood that English may not be your first language, but if you understand it well enough to abbreviate almost every word then surely you can make an attempt to write the word in full. Dont worry about the odd spelling mistake as Im sure most people can work around them - but having to decipher txt-spk is just a pain in the butt.

2) Asking for fully written code just is not going happen, you must attempt these things yourself using articles/books/documentation, and when you hit a specific proplem then come and ask about that problem. Dont expect somebody to do this for you for free.

3) Please do not ask for answers to be mailed directly to you, this board and every other technical forum, is there for everybody to learn from.

Re: want code for add,del,update to db (c#)

Kodanda Pani7-Mar-05 1:01

Kodanda Pani

7-Mar-05 1:01

Hi,

You can connect to the database and do all these operations using Connection, Command, DataReader, DataAdapter classes.

SqlConnection conn = new SqlConnection();
conn. ConnectionString = ""; //Set the connection parameters
SqlCommand cmd = new SqlCommand("");//pass SQl query
conn.Open(); // Open the connection
cmd.Connection = conn;
SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);//execute the command

Read MSDN for more help.

Thanks
SGS

C++ and Bios

SESCO LIBYA3-Mar-05 22:42

SESCO LIBYA

3-Mar-05 22:42

hi How i can get a size of RAM and a speed of prossesor by C++ (borland) ?

Re: C++ and Bios

leppie3-Mar-05 23:38

leppie

3-Mar-05 23:38

Not here. This the C# forum.

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Windows Service & SendMessage

s211197923-Mar-05 22:15

s21119792

3-Mar-05 22:15

Hi Guys,

I get the handle of my "windows service" by using

<br />
System.Diagnostics.Process proc = Process.GetCurrentProcess();<br />
log.WriteEntry(proc.Handle);<br />

I install a WH_CALLWNDPROC hook to capture any windows messages that my "windows service" might receive.

If use Sendmessage(proc.Handle,0x0308,IntPtr.Zero,IntPtr.Zero); to send a message to my service, the hook doesn't pick it up.

Does anyone know why this wouldn't work ????

Re: Windows Service & SendMessage

mav.northwind3-Mar-05 22:23

mav.northwind

3-Mar-05 22:23

Hi!.

SendMessage is sending messages to windows using their window handle.
You're fetching the process handle of your process.

These are two completely different things.

A process doesn't have to have one or more windows associated with it, so you can't just exchange different handles.

Regards,
mav

Re: Windows Service & SendMessage

s211197923-Mar-05 22:38

s21119792

3-Mar-05 22:38

Thanks for the info.

So is there any way that i can send a windows message to a windows service.

Re: Windows Service & SendMessage

mav.northwind4-Mar-05 0:45

mav.northwind

4-Mar-05 0:45

Only if your service creates a window that windows messages can be sent to.
Usually a service isn't allowed to perform desktop operations, so creating a window from a service for communication isn't usually the best way.
I think you should consider a different way of IPC, depending on what you want to do.

Regards,
mav

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