Comments for C# and stuff http://blog.kjeldby.dk Patterns and best practices in software development ... Fri, 06 Aug 2010 17:46:18 +0200 hourly 1 http://wordpress.org/?v=3.0 Comment on Overflow, checked and unchecked by Kristoffer Brinch Kjeldby http://blog.kjeldby.dk/?p=84&cpage=1#comment-263 Kristoffer Brinch Kjeldby Fri, 06 Aug 2010 17:46:18 +0000 http://blog.kjeldby.dk/?p=84#comment-263 Hi Chunkit Yeps - The check happens before the addition. Regarding optimization I suspects that the compile will not replace a checked operation with an unchecked, when it is explicit written in the code even - if the check is redundant. I have not checked this however. I you want to go into the msil code, you can use the MSIL Disassembler (Ildasm.exe). Regards Kristoffer Hi Chunkit

Yeps – The check happens before the addition.

Regarding optimization I suspects that the compile will not replace a checked operation with an unchecked, when it is explicit written in the code even – if the check is redundant. I have not checked this however. I you want to go into the msil code, you can use the MSIL Disassembler (Ildasm.exe).

Regards Kristoffer

]]> Comment on Overflow, checked and unchecked by chunkit http://blog.kjeldby.dk/?p=84&cpage=1#comment-260 chunkit Tue, 03 Aug 2010 02:53:43 +0000 http://blog.kjeldby.dk/?p=84#comment-260 I made a mistake in my previous comment. b < 255 is correct. I made a mistake in my previous comment. b < 255 is correct.

]]> Comment on Overflow, checked and unchecked by chunkit http://blog.kjeldby.dk/?p=84&cpage=1#comment-259 chunkit Tue, 03 Aug 2010 02:29:45 +0000 http://blog.kjeldby.dk/?p=84#comment-259 The third code should be i < 256 and b < 256. Depending on what you want, you may want to throw an exception if !(b < 256). I guess the performance penalty for using checked is that it checks both b++ and i++, but I can't be sure unless I look into the msil code (haven't learnt to do that yet). Perhaps a good compiler will optimize away the checking on integral variables that can be determined at compile-time never to cause an OverflowException. The third code should be i < 256 and b < 256.
Depending on what you want, you may want to throw an exception if !(b < 256).

I guess the performance penalty for using checked is that it checks both b++ and i++, but I can't be sure unless I look into the msil code (haven't learnt to do that yet). Perhaps a good compiler will optimize away the checking on integral variables that can be determined at compile-time never to cause an OverflowException.

]]> Comment on Microsoft Team Foundation Server: Moving from Visual Source Safe by Nick Yilmaz http://blog.kjeldby.dk/?p=302&cpage=1#comment-258 Nick Yilmaz Sat, 31 Jul 2010 20:22:19 +0000 http://blog.kjeldby.dk/?p=302#comment-258 Is it possible to control version of programs with TFS? For instance, a student submits a source code of project to the teacher and the teacher respond back to student with comment in the program. Is it possible to control version of programs with TFS? For instance, a student submits a source code of project to the teacher and the teacher respond back to student with comment in the program.

]]> Comment on Microsoft Team Foundation Server: Moving from Visual Source Safe by Kristoffer Brinch Kjeldby http://blog.kjeldby.dk/?p=302&cpage=1#comment-227 Kristoffer Brinch Kjeldby Wed, 05 May 2010 16:08:54 +0000 http://blog.kjeldby.dk/?p=302#comment-227 Thanks! TFS 2010 is so much easier to handle! Thanks! TFS 2010 is so much easier to handle!

]]> Comment on Microsoft Team Foundation Server: Moving from Visual Source Safe by Lani http://blog.kjeldby.dk/?p=302&cpage=1#comment-226 Lani Wed, 05 May 2010 11:14:52 +0000 http://blog.kjeldby.dk/?p=302#comment-226 Very well written and informative article. It was nice to get your thoughts on this as we currently are evaluating TFS 2010. Thank you. Very well written and informative article. It was nice to get your thoughts on this as we currently are evaluating TFS 2010. Thank you.

]]> Comment on Paths in User Controls by Daniel Ballinger http://blog.kjeldby.dk/?p=17&cpage=1#comment-210 Daniel Ballinger Fri, 09 Apr 2010 02:09:06 +0000 http://blog.kjeldby.dk/?p=17#comment-210 When using a HTML server control setting the AppRelativeTemplateSourceDirectory property can resolve the path to a directory outside the user controls path. When using a HTML server control setting the AppRelativeTemplateSourceDirectory property can resolve the path to a directory outside the user controls path.

]]> Comment on Rotation around an vector in C#/XNA by Kristoffer Brinch Kjeldby http://blog.kjeldby.dk/?p=3&cpage=1#comment-102 Kristoffer Brinch Kjeldby Thu, 26 Nov 2009 18:55:50 +0000 http://blog.kjeldby.dk/?p=3#comment-102 Here is some psedo code: <code> Vector 2D Rotate(Vector2D p, Vector2D o, Degrees d) {   var r = new Vector2D();   r.X = o.X+cos(d)*(p.X-o.X)         -sin(d)*(p.Y-o.Y);   r.Y = o.Y+sin(d)*(p.X-o.X)         +cos(d)*(p.Y-o.Y);  return r; } </code> p is the vector you want to rotate, o is the center around which you want to rotate and d is the degrees. You can read more here: http://gpwiki.org/index.php/VB:Rotating_A_Point_In_2D Here is some psedo code:

Vector 2D Rotate(Vector2D p, Vector2D o, Degrees d)
{
  var r = new Vector2D();
  r.X = o.X+cos(d)*(p.X-o.X)
        -sin(d)*(p.Y-o.Y);
  r.Y = o.Y+sin(d)*(p.X-o.X)
        +cos(d)*(p.Y-o.Y);
 return r;
}

p is the vector you want to rotate, o is the center around which you want to rotate and d is the degrees.

You can read more here: http://gpwiki.org/index.php/VB:Rotating_A_Point_In_2D

]]> Comment on Rotation around an vector in C#/XNA by Mayur http://blog.kjeldby.dk/?p=3&cpage=1#comment-99 Mayur Sat, 21 Nov 2009 09:35:53 +0000 http://blog.kjeldby.dk/?p=3#comment-99 Thats an excellent post.. However i would like to know wht i'll changes wld i have to make to make it work for a 2-D matrix. What i need is the implementation of Matrix.Rotate() method of WPF in Silverlight, since silverlight does not have any inbuilt method for matrix rotation. Thats an excellent post.. However i would like to know wht i’ll changes wld i have to make to make it work for a 2-D matrix.
What i need is the implementation of Matrix.Rotate() method of WPF in Silverlight, since silverlight does not have any inbuilt method for matrix rotation.

]]> Comment on Strings the right way by Kristoffer http://blog.kjeldby.dk/?p=21&cpage=1#comment-59 Kristoffer Sun, 05 Jul 2009 22:39:02 +0000 http://blog.kjeldby.dk/?p=21#comment-59 Hi Suiden Thanks for your comments. You right a long way here, but in my exact example: string s1 = "Hello"; s1 = s1 + " world"; Even an optimized compilation produces the following MSIL: .locals init ([0] string s1) ldstr "Hello" stloc.0 ldloc.0 ldstr " world" call string [mscorlib]System.String::Concat(string, string) stloc.0 Now, I am not even close to being a IL expert - but this MSIL code is not optimized in the way you describe. The string "Hello" is pushed onto the stack, and is location stored in the local variable 0 (s1) - then after the concat have been performed (and the result stored on the stack), variable 0 is redirected to the new location. The pivotal point is, that I create s1 as a named variable first. If i instead write: s1 = " Hello" + " world"; or s1 = String.Concat("Hello", " world"); Only one string is created. So you are right concerning my last example with Concat. Hi Suiden

Thanks for your comments. You right a long way here, but in my exact example:

string s1 = “Hello”;
s1 = s1 + ” world”;

Even an optimized compilation produces the following MSIL:

.locals init ([0] string s1)
ldstr “Hello”
stloc.0
ldloc.0
ldstr ” world”
call string [mscorlib]System.String::Concat(string, string)
stloc.0

Now, I am not even close to being a IL expert – but this MSIL code is not optimized in the way you describe.

The string “Hello” is pushed onto the stack, and is location stored in the local variable 0 (s1) – then after the concat have been performed (and the result stored on the stack), variable 0 is redirected to the new location.

The pivotal point is, that I create s1 as a named variable first. If i instead write:

s1 = ” Hello” + ” world”;

or

s1 = String.Concat(“Hello”, ” world”);

Only one string is created. So you are right concerning my last example with Concat.

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