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Re: how can communicate with a router

Heath Stewart20-Apr-04 8:51

20-Apr-04 8:51

This is specific to the firmware for the router. You need to consult the router manufacturer web site for details, if any are provided.

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Re: how can communicate with a router

Klaus Weisser20-Apr-04 9:17

20-Apr-04 9:17

use SNMP to communicate with the router.
but I haven't done something like this in c# til now.

Re: how can communicate with a router

Anonymous23-Apr-04 17:43

23-Apr-04 17:43

wht u say about ICMP.

Embed C# controls in MFC views/dialogs

rkvs20-Apr-04 7:51

20-Apr-04 7:51

Dear forum members,

I have controls (UserControl) designed in C#.
Can anyone tell me how I can embed them in MFC dialogs/views (in VC7) ?
Any sample code will be very helpful.

Thanks in advance.

Re: Embed C# controls in MFC views/dialogs

Heath Stewart20-Apr-04 8:48

20-Apr-04 8:48

Without having to create a shim, you can expose your UserControl as a COM object and then embed the COM object (which uses the mscoree.dll as a shim) in your dialog.

See Creating a CCW for COM-enabled non-.NET Applications[^] for more information.

There's also the book, Extending MFC applications with the .NET Framework[^] written by a couple of CPians which you may be able to find more information about here on CodeProject.

Microsoft MVP, Visual C#
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serial communication in c#

balsmn20-Apr-04 7:34

20-Apr-04 7:34

hi,
do u know how to write and read from serial port. actually i have done the write and read but i do not know how to configure the port.
do anyone know in c#?

bye thank u

Re: serial communication in c#

Heath Stewart20-Apr-04 8:37

20-Apr-04 8:37

There are several articles on this here on CodeProject and it has been covered before in this forum. Please search the CodeProject site for more information.

Microsoft MVP, Visual C#
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Re: serial communication in c#

Marc Clifton20-Apr-04 13:37

20-Apr-04 13:37

I've evaluated several serial I/O packages that were posted here on CP, and none of them worked.

The only one that I found that worked (and temperamentally at that), was this one:

http://msdn.microsoft.com/msdnmag/issues/02/10/netserialcomm/[^]

Written by John Hind. Good luck!

Marc

Microsoft MVP, Visual C#
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Small string building question

Le centriste20-Apr-04 6:26

20-Apr-04 6:26

Often, in my code, I use the following construct:

string someStr = "sdlkfj" + someOtherStr + "slkdfj";

One of my colleague rather uses the following:

string someStr = String.Format("sdlkfj{0}slkdfj", someOtherStr);

Which one do you think is better, and why?

Thanks

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: Small string building question

Jeremy Kimball20-Apr-04 6:37

20-Apr-04 6:37

If your code uses "your way" of doing things often, your colleague's way is better. Performing the operation the way you specified:

string x = "bob" + stringObj + "bob";

actually allocates memory for all three RHS values (iirc), not to mention the fact that string concatenation in itself is not particularly speedy or memory efficient.

However, if you only use it sparingly, or in non-critical sections, your way doesn't really have a problem either. I generally use string concatenation unless performance becomes an issue, in which case I usually switch over to a StringBuilder.

Jeremy Kimball

magnae clunes mihi placent, nec possum de hac re mentiri.
(Large buttocks are pleasing to me, nor am I able to lie concerning this matter)

Re: Small string building question

Mike Dimmick20-Apr-04 6:45

20-Apr-04 6:45

Jeremy Kimball wrote:
actually allocates memory for all three RHS values

Actually, it doesn't. The C# compiler compiles simple string concatenation to calls to String.Concat, which only allocates once.

StringBuilder also has interesting issues: see Concatenating with StringBuilders vs strings[^].

Stability. What an interesting concept. -- Chris Maunder

Re: Small string building question

Heath Stewart20-Apr-04 8:33

20-Apr-04 8:33

The strings are still allocated each time:

string s = string.Concat("One", "Two", "Three");

...still allocates three strings in order to concatenate them.

Microsoft MVP, Visual C#
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Re: Small string building question

Jeff Varszegi20-Apr-04 9:33

20-Apr-04 9:33

Not necessarily true: for each, if it's in the intern pool, the interned string will be returned instead of a newly-created object. At least, that's my understanding. (Check the documentation of String.Intern for a starting point.) From this standpoint, if you have commonly-occurring small strings and go assembling them into formatting strings just to use String.Format(), you will incur extra string-creation overhead PLUS the slowness of the method itself!

Regards,

Jeff Varszegi

Re: Small string building question

Mike Dimmick20-Apr-04 6:42

20-Apr-04 6:42

The Format version is more costly in performance. However, it is vastly more flexible; you can position the item to be replaced anywhere in the string. You can even place formats in a different order to the order they're passed to Format, or use the same replacement multiple times. This makes it easier to localize displays for different cultures.

Multiple string concatenations with + in the source code are compiled to calls to String.Concat by the C# compiler, and so don't cause any extra overhead in terms of memory usage.

I'd use Format for any strings presented to a user and which therefore might be localized, and + for any internal string operations.

See also Rico Mariani's blog[^] (a performance architect on the .NET Framework team at Microsoft).

Stability. What an interesting concept. -- Chris Maunder

Re: Small string building question

Jeff Varszegi20-Apr-04 6:58

20-Apr-04 6:58

easier to localize displays for different cultures

Great point. I guess that goes for any output that's configurable, too. -Jeff

Re: Small string building question

Jeff Varszegi20-Apr-04 6:56

20-Apr-04 6:56

I think that there are two main possible benefits to some approach: simplicity/ease of understanding and maintenance, and performance. On a line-by-line basis, I always lean in favor of performance, so I would advise you to use whatever works fastest. I often perform small benchmarks if I am not sure of which version of a code section would work best; this gives me a good understanding of how code performs, and I constantly add to this knowledge.

I discovered in the past that String.Format() can be pretty slow, and that's what I found this time. Run the code on your setup and see which comes out on top. -Jeff

C#

<br />
        string sdlkfj = "sdlkfj";<br />
        string someOtherString = "blah";<br />
        string formatString = "sdlkfj{0}slkdfj";<br />
        string product = null;<br />
<br />
        int loopCount = 100000;<br />
        long startTime, endTime;<br />
        <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine( (((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />
              <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine( (((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />
<br />

Re: Small string building question

Le centriste20-Apr-04 8:30

20-Apr-04 8:30

Yes, I will try that for sure.

Thank you.

--------

"I say no to drugs, but they don't listen."
- Marilyn Manson

Re: Small string building question

Jeff Varszegi20-Apr-04 9:50

20-Apr-04 9:50

You're welcome! -Jeff

Re: Small string building question

Heath Stewart20-Apr-04 8:36

20-Apr-04 8:36

In this case, it is much better to use a StringBuilder. A String is immutable so anything you do to it allocates a new string and copies the chars. A StringBuilder is mutable so you are changing the same string without re-alloc'ing new strings each time.

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Re: Small string building question

Jeff Varszegi20-Apr-04 9:22

20-Apr-04 9:22

Nope. Like you, I often use StringBuilder, especially if I'm constructing a large string in several steps. It's not always faster, though. Try running the code below on your machine-- I came up with these readings:

190.2736 nanoseconds
951.368 nanoseconds
390.5616 nanoseconds
400.576 nanoseconds

Regards,

Jeff Varszegi

C#

<br />
        string sdlkfj = "sdlkfj";<br />
        string someOtherString = "blah";<br />
        string formatString = "sdlkfj{0}slkdfj";<br />
        string product = null;<br />
<br />
        int loopCount = 100000;<br />
        long startTime, endTime;<br />
        <br />
        <br />
        <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
            product = sdlkfj + someOtherString + sdlkfj;<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine((((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />
              <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
            product = String.Format(formatString, someOtherString);<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine((((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />
        <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder()).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine((((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />
        <br />
        <br />
        startTime = DateTime.Now.Ticks * 100;<br />
        for(int x = 0; x < loopCount; x++) {<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
            product = ((new StringBuilder(16)).Append(sdlkfj).Append(someOtherString).Append(sdlkfj)).ToString();<br />
        }<br />
        endTime = DateTime.Now.Ticks * 100;<br />
        Console.WriteLine((((double)(endTime - startTime)) / ((double)(loopCount * 10))) + " nanoseconds" );        <br />

Re: Small string building question

Heath Stewart20-Apr-04 9:26

20-Apr-04 9:26

Because you don't reinstantiate the StringBuilder! You use the same one over:

StringBuilder sb = new StringBuilder();
for (int i=0; i<1000; i++)
{
  sb.Append("Some string");
  sb.Append(i.ToString());
}
Console.WriteLine(sb.ToString());

Of course it's going to take longer when you keep needlessly reinstanting a StringBuilder.

Microsoft MVP, Visual C#
My Articles

Re: Small string building question

Jeff Varszegi20-Apr-04 9:36

20-Apr-04 9:36

Aha! But that's done on purpose-- I intentionally duplicated exactly what his code would be doing if it used a StringBuilder. Every instantiation and method call. And as Mike Dimmick pointed out, StringBuilder has certain issues that should be considered.

Regards,

Jeff Varszegi

Re: Small string building question

Jeff Varszegi20-Apr-04 9:41

20-Apr-04 9:41

I just tested, and even avoiding the extra object creation by resetting the same StringBuilder each time, the StringBuilder solution only improves about ten percent, still about exactly twice as slow as the original poster's preferred method. I can post the code if you want, but I figure it's a snap for you to test yourself if you still don't believe me.

Regards,

Jeff Varszegi

Re: Small string building question

Heath Stewart20-Apr-04 9:51

20-Apr-04 9:51

It's not that I don't believe you, it's just that you were using the StringBuilder "incorrectly". I know that in some cases his preferred way may be better, but in most cases - apparently not this one - it is. Instead of continually calling Append, too, you can also use AppendFormat. I really don't care to see what the difference is, though, I'm just trying to make a point. AppendFormat is, after all, what String.Format is using so I know there's a lot of instructions required that search for the format parameter indexes and apply any format specifications using information from the Type that is in that parameter position, such as checking for IFormattable or using the IFormatProvider to get ICustomFormatter implementations for a specific type.

Microsoft MVP, Visual C#
My Articles

Re: Small string building question

Jeff Varszegi20-Apr-04 10:02

20-Apr-04 10:02

It's really no problem. I'm just a speed freak when it comes to my code, and I'm constantly fiddling around to see what works fastest, sort of an object-oriented hot rodder. Wotta geek, eh? It's just my thing. I don't claim to be an all-around .NET expert, just pretty good with language features. Some of the questions you answer immediately on this board would take me a while.

I tend to use StringBuilder more now only when constructing large strings (although when I first made the jump from Java I used it religiously). It gives really good performance and lets you write your code in a normal way, without breaking lines. Every time I create one, though, I'm in the habit of just throwing it away; I figure that the bigger the string and related work, the less and less the instantiation of one object matters. Not only that, but if you construct strings of different sizes, and you get a really big one once in a while, I believe the internal char array of a StringBuilder will never shrink, which in some cases could be a problem.

Regards,

Jeff Varszegi

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