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Software_Specialist wrote: I guess to use XNA i have to install VS2005 express edition and now to install that i need to uninstall my proffesional version....
Then you guessed wrong. I have both professional and Express editions installed side by side and it causes no problems.
Software_Specialist wrote: should go with XNA by overcoming all the complexities as i dont want to uninstall VS proffeional version .
You don't have to uninstall VS professional edition. Where did you hear that anyway?
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Oh yeh i was wrong it was for the beta version....
Not for prof...I guess i should give it a try with XNA..
Ill download this express version now..
Thanks..
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Dear all,
I want read Excel file and create another new Excel file with the data inside a first file. how can select a Column in a Excel file than compare this Column to another and so on, than colect this columns and create a new file from that colected columns.
-- modified at 17:49 Saturday 13th January, 2007
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Office applications expose a COM-based object model. If using .NET, they also include PIAs (Primary Interop Assemblies) that wrap the object model in a slightly more .NET-friendly manner. You could use this model to open, extract from, and write to Excel files.
See: Excel Object Model[^]
-Phil
Disclaimer: I work for Microsoft as a developer on the Visual Studio Tools for Office product team.
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hi
i want to manage device(s) (for example send/recieve date) from usb device. does anybody can help me (tutorial,article,sample or ...) ?
thanks
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Say some of our program resource is on CD, but we don't know which one (and want to use any available), what is best way to check available drives, and then check if disk we want is one of them?
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If using .NET 2.0 there is System.IO.DriveInfo which gives you:
- all the drive letters
- so scan them one by one, and for each drive
- check drive type (check for DriveType.CDRom)
- check volume label (check for your CD's label).
If using .NET 1.1 you can follow the same scheme, but you would need PInvoke to
Win32 functions such as GetVolumeInformation (And that's exactly what I did today !)
Luc Pattyn
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Visual C# 2005 EE so it's 2.0, I'll try that now...
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OK got it thanks...
link for good example on that:
http://msdn2.microsoft.com/en-us/library/system.io.driveinfo.getdrives.aspx
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hi all
i install vs2005 and msdn 2005,but msdn does not exist in my visual studio IDE,how to confugure it correctly ?
thanks.
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As far as I know it involves a re-install.
I have no idea what I just said. But my intentions were sincere.
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I am not at my vs2005 IDE right now but in vs2003 you can access help information in Tools->Options->Environment->Help.
If that doesn't work I would suggest a reinstall or possibly you could find the main help application that should have been installed with the MSDN library.
Regards,
Thomas Stockwell
Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.
Visit my homepage Oracle Studios[ ^]
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Hi everybody
I'm doing a project were I need to do some advanced calculations on complex numbers. So I'm wondering if I should use a struct/class to represent the Complex data or should I use two arrays of primitive types to handle the real and complex part seperately. Is it more memory effecient to use primitive types than self-defined types?. I have read somewhere that primitive types in C# are objects themself, so I was wondering, if I define e.g a ComplexNumber class, would it be the same as using e.g float which is inheritet from System.Object?...
Thanks in advance
T
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Take a look at the following MSDN resource to learn something about the Class and struct differences[^]. To come to your concrete problem: I would define a ComplexNumber structure because the primitive types like int or double are structures too and this way the general handling of a ComplexNumber would be similar to dealing with another primitive type.
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook www.troschuetz.de
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Hi,
A ComplexNumber class would use 16 bytes to store two 4B numbers (real+imag parts) plus 8B of
administrative stuff. So it effectively doubles the memory requirements, which
is only really significant if you are going to need more than 1M of those numbers.
I am not sure whether a struct has the same memory overhead or not.
But this is simple to find out: just create a small program than creates 1M complex numbers
(as 2 floats, as a struct, as a class) and in each case compare its memory footprint
before and after creation (make sure the objects are still alive when you measure (e.g.
by including code to sum them up, then print the sum).
The calculation cost will be different too. With a class, the natural way would be
to write methods that return a new object (say c=a+b), which involves calling the method,
doing very simple arithmetic, creating a new object, and returning it. (And this is
what you would have to do if you want to overload the + - * operators)
A cheaper approach would be to provide methods that do not return results, but modify
their parameters, something like:
static void AddTo(ComplexNumber a, ComplexNumber b); // performs a=a+b
of course, if ComplexNumber is a struct, you would use ref everywhere (obviously for
in/out values, but I recommend it for input-only parameters too).
The cheapest, but hardest way, would be to forget about a complex class/struct and
write everything in real numbers, with explicit add/multiply code all over the place.
Completely unstructured, very error prone and the fastest (at run-time that is).
If your application needs a lot of complex functions (hence a lot of code), I would
go for a class with overloaded operators, so you can really write c=a+b with abc all complex.
If the number of formulas is limited, I would suggest you start with a ComplexNumber struct
and use explicit method calls for each operation; but avoid creating objects all the time,
and certainly do not rely on methods that return a struct: instead have them modify an
already existing struct.
If in the end you are still convinced it needs to be faster and/or smaller, you could
then revisit the initial choice. But dont start it in the hard way from day 1.
But I do not expect you to really need this, unless you are chasing the next Mersenne prime
or so...
Hope this is helpful.
Luc Pattyn
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Thanks for your answers guys
It really cleared some things up for me. The thing is that I'm doing some complex numbers math on sound data, so memory space is important. I'm using about 2^16=131072 samples data and if I do the Fourier transformation this will double up, because of the complex representation. This will end up something like 2^16*2*16=4194304 bytes ~4.2M which is a lot. So I'm thinking maybe I should do it the hard way...
If you you have something to add I'm open to suggestions...
Best wishes
T
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I'm not sure I completely follow your reasoning here. The native data types like int, byte, datetime, etc. are all structs. A struct automatically inherits from System.ValueType. If I were implementing a ComplexNumber object, I would want it to have the same behavior as the native data types.
A struct also allows you to overload operators, so there would be no problems implementing code like c = a + b. Also, if the code is going to be creating a lot of these types of objects, which it sounds like it would be, you don't want the extra overhead of creating a class each time and having to store it on the heap.
I would take a look at how one of the native data types are defined using either reflector or Rotor and pattern the object from that.
-----------------------------
In just two days, tomorrow will be yesterday.
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Sure, for ease of use I would implement ComplexNumber as a class or struct, with operators
overloaded.
For performance reasons I would rather not use classes (too many objects), and not
return structs (too many data moves; for 8B of data it is debatable, for large structs
I certainly dont want them returned), hence ref struct, hence no operator overloads.
And of course for max performance, no ComplexNumbers at all.
Luc Pattyn
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Luc Pattyn wrote: Sure, for ease of use I would implement ComplexNumber as a class or struct, with operators
overloaded.
I guess your original post didn't seem clear to me.
Luc Pattyn wrote: For performance reasons I would rather not use classes (too many objects), and not
return structs (too many data moves; for 8B of data it is debatable, for large structs
I certainly dont want them returned), hence ref struct, hence no operator overloads.
From the MSDN[^] docs:
A struct can be considered a lightweight class, ideal for creating data types that store small amounts of data, and does not represent a type that might later be extended via inheritance.
I don't see how the performance of a struct is going to be detrimental if the "rules" are followed. Again, all of the native data types are implemeneted using structs and there aren't any perforamnce issues with them.
-----------------------------
In just two days, tomorrow will be yesterday.
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Hi again
I have read a bit up on which types to prefer and it seems to me that defining a struct and using it as a primitive type, would be the same as just using primitive types which are structs themself. This means that if I want to represent some complex data (Re,Im). I could do it using two e.g float arrays representing the real part and the imag part, but it would be the same, if I used a struct called Complex(float,float).
In other words:
float[] = realdata;
float[] = Imagdata;
would be the same as:
Complex[,] = new Complex(realdata,Imagdata);
Right? 
All the best
T
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You are essentially correct. The benefit to defining your own struct is that you can then ecapsulate the two parts of a complex number and define the arithmetic rules (+, -, etc.) which allows you to treat the complex number as if it were a native data type.
I'm not sure why you would want to use arrays in the way you are showing. Defining a ComplexNumber struct would allow you to do something like this:
ComplexNumber c = new ComplexNumber(real, imaginary);
Console.WriteLine("Complex Number Real: {0}, Imaginary: {1}", c.Real, c.Imaginary);
ComplexNumber d = new ComplexNumber(real2, imaginary2);
ComplexNumber e = c + d;
Console.WriteLine("Complex Number Real: {0}, Imaginary: {1}", e.Real, e.Imaginary);
The benefit here is that the ComplexNumber knows how to add two complex numbers together and the calling code doesn't need that complexity.
If you wanted to use this in an array, it would be something like this:
Complex[] complexArray = new Complex[3];
complexArray[0] = new ComplexNumber(real, imaginary);
complexArray[1] = new ComplexNumber(real2, imaginary2);
complexArray[2] = new ComplexNumber(real3, imaginary3);
-----------------------------
In just two days, tomorrow will be yesterday.
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Hi again
Thanks for the answer.
I agree on what you are saying, this is how I have done it through out my project. I just wanted to know if there possible was a better way. My concern was that when I use a Complex array of e.g 100000 values and every time using the "new" inside a loop and thereby assigning a new memory location every time, would lead to a unnessecery usage of memory. So initially I was wondering if this could be avoided using primitive types. But this does not seeme to be the case - I think
All the best
T
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