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There are a number of problems where a recursive algorithm is both simpler and faster than an loop.
For example QuickSort[^]
is one of the fastest sorting algorithm that have been found and it is using recursion.
http://en.wikipedia.org/wiki/Tower_of_Hanoi[^] is another example where recursion is really paying.
There are many more situation where recursion is needed.
It makes sense each time you can solve a problem by applying the same methods on its bits.
One of the typical example is a function that copy a folder somewhere else.
If you were to program it without recursion you would have to write:
function copyfolder(folder)
for each file in folder
copy file
next
for each subfolder in folder
for each file in subfolder
copy file
next
for each subsubfolder in subfolder
for each file in subsubfolder
copy file
next
... what if there is some subsubsubfolders?
next
next
end function
Using a recursive algorithm you would have less code
function copyfolder(folder)
for each file in folder
copy file
next
for each subfolder in folder
copyfolder(subfolder) ... this line is where the recursion happen
next
end function
Signature
Seen in CodeProject forums :
Is it a sort of male dominance thing? You know, who can be the most witty? Who considers themselves the clown at the party?
Is it a follow the leader thing? One can't be seen not to have an elaborate signature, it's just no right, after all, all the other people have one.
(Is that long enough?)
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What are the tools of black box testing & white box testing,,?/plz names
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Are these your homework questions by any chance? Stop being so lazy and go do some research yourself. Google and Wikipeida will answer all of these for you.
Simon
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waqarnaeem2@hotmail.com wrote: What are the tools of black box testing & white box testing
A French nuclear submarine and the Brazilian Navy.
Man who stand on hill with mouth open wait long time for roast duck to drop in
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waqarnaeem2@hotmail.com wrote: tools of black box testing & white box testing
Look for a natural blonde, as opposed to a bleached blonde.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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There isn't a de facto app for testing. You can use ANY product that records keystrokes/mouse-events and plays them back for blackbox-testing. For white-box testing, I'd recommend the Visual Studio debugger.
You might want to dive into TDD[^].
I are troll 
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why Interface supports multiple inheritance ? & why abstract class don't?what is the reason?
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It was a decision taken in the original design on C#. Multiple inheritance is deemed to complex, without enough benefits.
Inheritance is often described as an "is-a" relationship. I.e. a Car is-a vehicle so the car class inherits from vehicle. Usually, when people try and do things with multiple inheritance, what they are doing is forming a "has-a" relationship, which would be better represented as a class that contains the other class, rather than inherits from it. There aren't many cases where you have an object that is two separate types of sub objects. A Car is-a vehicle and a car also is-a ManMadeItem, but this forms a hierarchy (Car->Vehicle-ManMadeItem) so multiple inheritance isn't needed. If you look at your design, I think you'll find in almost all cases where you have multiple inheritance you can either change it to a hierarchy or a composition instead.
Even in languages that support it, it is general discouraged.
http://en.wikipedia.org/wiki/Multiple_inheritance#Criticisms[^].
There's an article here[^] about a possible way to achieve it in C#, but I don't recommend it for anything beyond academic interest.
Simon
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Simon Stevens wrote: A Car is-a vehicle and a car also is-a ManMadeItem, but this forms a hierarchy (Car->Vehicle-ManMadeItem) so multiple inheritance isn't needed
I don't think I'd regard that as a hierarchy, because a horse could also be regarded as a Vehicle even though it is not a ManMadeItem.
I think the simplest way to look at the issues of inheritance versus interface is that an inherited base class can supply default fields and methods which are then usable by child classes; an interface not only does not provide default storage for fields and code for methods, but it can't even bind them by default. If an object inherited from Class1 and Class2, both of which provided a Smile method, it would be unclear whether TheObject.Smile was supposed invoke Class1.Smile or Class2.Smile. With interfaces, however, there is no problem. TheObject must have an "implements" line for every interface method it supports, indicating what method should be used for Interface1.Smile and which one should be used for Interface2.Smile. Further, to actually use either of those methods on an object, the object must first be cast to Interface1 or Interface2. Thus, there is no ambiguity.
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Because interface doesn't contain any definitions to any declarations but abstract class does.
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waqarnaeem2@hotmail.com wrote: why Interface supports multiple inheritance ?
It doesn't. Interfaces define an implementation contract. You don't inherit anything from an interface, it just forces you to implement the interface.
Man who stand on hill with mouth open wait long time for roast duck to drop in
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Hi,
I'm really hoping for an easy answer to this issue. I have a client device that uses a hardwired connection to communicate with its server if it is in a docking station. If lifted from the docking station the hardwired connection is disabled and it switches to its wireless connection. This is where remoting stops working on the serverside.
The client device has 2 network cards with different IPs, one for the hardwired connection and one for the wireless connection. When switching to wireless/hardwired the client is still able to send messages to the server, but apparently the server is still trying to reach the client on the connection it initially used so the return messages fail.
How is this fixed? Where is this fixed? I've tried to call RemotingServices.Configure again but it seems you can only call that once. Unregistering and re-Registering channels doesn't seem to work either. Any ideas would be greatly appreciated! Solutions even more!
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I have a Winforms project in which I am trying to Publish. I get the problem that says "keyset does not exist". I have no idea what to do. Any ideas?
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Something to do with assembly signing I would guess, since that uses cryptographic keysets.
What are your assembly signing settings?
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.freetls.fastly.net/script/Forums/Images/coffee.gif)
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I seemed to have fixed the problem (not sure how I did it, and I hope I can do it again in the future!) But I have another problem. When I run the setup app, I get the Application Install dialog, and it gives the name. I would like to change this name since somehow the name has a date associated with it (and the date has since changed.) I did a search throughout the whole project for the date, and could nto find it. Perhaps it is in the registry somehow?
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I'm just guessing again, but what about the Options dialog on the Publish page of the project's properties?
If you set the name(s) there instead of using the defaults does that fix anything?
Mark Salsbery
Microsoft MVP - Visual C++
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Mark, your suggestion worked. The product name was right there!
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Cool! Lucky guess 
Thanks for the update!
Mark Salsbery
Microsoft MVP - Visual C++
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Hi All,
I've spent the last couple of hours looking into a pretty big topic and I don't really feel like I've made any progress on the topic. I'm getting emails from potential users of my application concerned/worried/annoyed about the fact that my app may require a massive download for offline installation (a common scenario for my users).
My app targets XP SP2+ users on 32/64 bit OSes. My app is a .NET 3.5 SP1 based WPF product.
My installer already checks for 3.5 SP1 and contains the dotnetfx35setup.exe that will only download the required bits if the required framework version isn't installed. So for online users the problem isn't massive. However, I would like to make a single self-sufficient install .exe file that can take care of all users rather than pointing offline users to a 200mb+ installer on the Microsoft site.
I've been looking through the myriad files that make up the main dotnetfx35.exe and from what I can gather there isn't actually much I can strip out. Has anyone got any links of info on what can be done?
Scott Hansleman has some blog posts and this is pretty cool http://windowsclient.net/wpf/wpf35/wpf-35sp1-client-profile-deployment-photosuru.aspx[^] but I'm still none the wiser as to what I can actually get away with stripping out.
Considering that I'm including XP/Vista and 32/64 bit I still need to carry .NET2.0 / .NET3.0 / .NET3.5 stuff which is arguably nearly all of it!! Feels like I'm stuck with the massive download situation ...
Not to mention the worry of trashing a users .NET install altogether. Any info or pointers would be really appreciated.
Cheers,
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I've not played with the Client Profile, so I can't give any pointers there, but I do have another potential option for you. If your users have a worry on this, you could create two types of installs. One that has links to the redistributables, and the other that is merged together using ILMerge[^]. The ILMerge version would be a lot bigger than the other version, but it won't contain the whole framework, only the bits you need.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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Whoa, I'd forgotten about that util. Would it be safe to actually merge the system.dll / presentationcore.dll etc ... ?
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I've never really tried. Theoretically, you should be OK, but it would be worth experimenting.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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Gotcha. Will have a read around the subject and see what pops out!
Thanks Chap.
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Hi,
I'm trying to write application where I use series of PNG files for animations. I created control which loads Images from file into ArrayList, and then on specified timer interval I change picture that I want to display. I'm using 1280x720 PNGs.
I have 2 problems here:
1) My PNG is around 300KB, and when I execute Image.FromFile("my.png") memory of my process is increased for 4MB. So, if I load 30 pictures, memory will grow to around 130MBs and the problem is that I have to keep lot of images loaded into memory since I'm using it constantly during execution time.
2) performances of DrawImage functions are quite bad and I cannot get proper speed (if I need 25 frames per second for example)
Does anyone have some suggestions how to solve this?
Thnx in advance!
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Firstly, PNGs aren't really the best way to do animations. You should maybe think about using GIF images instead.
ddavor wrote: 1) My PNG is around 300KB, and when I execute Image.FromFile("my.png") memory of my process is increased for 4MB. So, if I load 30 pictures, memory will grow to around 130MBs and the problem is that I have to keep lot of images loaded into memory since I'm using it constantly during execution time.
I suspect (although I haven't tried it) that the 4MB jump is mainly a one-off overhead, and you won't get that increase on subsequent image loads. Try it and check though.
ddavor wrote: 2) performances of DrawImage functions are quite bad and I cannot get proper speed (if I need 25 frames per second for example)
You're drawing a 300KB 1280 x 720 PNG image, so I'm not surprised it's a bit slow...
An animated GIF will automatically play when loaded (although if you keep to that size it may still be a bit slow - again you'd need to test it) and if you can reduce the quality a bit you can probably reduce the file size to something more reasonable.
Alternatively, combine the images into an AVI and use a simple AVI player to show the animation.
There are three kinds of people in the world - those who can count and those who can't...
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