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  • functional, bind1st and mem_fun

    - by Neil G
    Why won't this compile? #include <functional> #include <boost/function.hpp> class A { A() { typedef boost::function<void ()> FunctionCall; FunctionCall f = std::bind1st(std::mem_fun(&A::process), this); } void process() {} }; Errors: In file included from /opt/local/include/gcc44/c++/bits/stl_function.h:712, from /opt/local/include/gcc44/c++/functional:50, from a.cc:1: /opt/local/include/gcc44/c++/backward/binders.h: In instantiation of 'std::binder1st<std::mem_fun_t<void, A> >': a.cc:7: instantiated from here /opt/local/include/gcc44/c++/backward/binders.h:100: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:103: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:106: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:111: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:117: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h: In function 'std::binder1st<_Operation> std::bind1st(const _Operation&, const _Tp&) [with _Operation = std::mem_fun_t<void, A>, _Tp = A*]': a.cc:7: instantiated from here /opt/local/include/gcc44/c++/backward/binders.h:126: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' In file included from /opt/local/include/boost/function/detail/maybe_include.hpp:13, from /opt/local/include/boost/function/detail/function_iterate.hpp:14, from /opt/local/include/boost/preprocessor/iteration/detail/iter/forward1.hpp:47, from /opt/local/include/boost/function.hpp:64, from a.cc:2: /opt/local/include/boost/function/function_template.hpp: In static member function 'static void boost::detail::function::void_function_obj_invoker0<FunctionObj, R>::invoke(boost::detail::function::function_buffer&) [with FunctionObj = std::binder1st<std::mem_fun_t<void, A> >, R = void]': /opt/local/include/boost/function/function_template.hpp:913: instantiated from 'void boost::function0<R>::assign_to(Functor) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' /opt/local/include/boost/function/function_template.hpp:722: instantiated from 'boost::function0<R>::function0(Functor, typename boost::enable_if_c<boost::type_traits::ice_not::value, int>::type) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' /opt/local/include/boost/function/function_template.hpp:1064: instantiated from 'boost::function<R()>::function(Functor, typename boost::enable_if_c<boost::type_traits::ice_not::value, int>::type) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' a.cc:7: instantiated from here /opt/local/include/boost/function/function_template.hpp:153: error: no match for call to '(std::binder1st<std::mem_fun_t<void, A> >) ()'

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  • Application settings methods? c++

    - by flyout
    I am thinking about adding configurable settings to an application, and I think the easiest ways are an external file or win registry (its a win only app). Which way would be better? I was wondering, an user with not enough permissions may not be able to create/write the config file. And in the case of the registry, would todays antivirus allow me to add/edit/remove keys? Or they only monitor certain keys? Also, if someone knows a class/lib to manage config settings (in pure win32) in vc++ please post it.

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  • Basic data alignment question

    - by Broken Logic
    I've been playing around to see how my computer works under the hood. What I'm interested in is seeing is what happens on the stack inside a function. To do this I've written the following toy program: #include <stdio.h> void __cdecl Test1(char a, unsigned long long b, char c) { char c1; unsigned long long b1; char a1; c1 = 'b'; b1 = 4; a1 = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&b1 - (long)&a1, (long)&c1 - (long)&b1, (long)&a - (long)&c1, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&a1 ); }; struct TestStruct { char a; unsigned long long b; char c; }; void __cdecl Test2(char a, unsigned long long b, char c) { TestStruct locals; locals.a = 'b'; locals.b = 4; locals.c = 'r'; printf("%d %d - %d - %d %d Total: %d\n", (long)&locals.b - (long)&locals.a, (long)&locals.c - (long)&locals.b, (long)&a - (long)&locals.c, (long)&b - (long)&a, (long)&c - (long)&b, (long)&c - (long)&locals.a ); }; int main() { Test1('f', 0, 'o'); Test2('f', 0, 'o'); return 0; } And this spits out the following: 9 19 - 13 - 4 8 Total: 53 8 8 - 24 - 4 8 Total: 52 The function args are well behaved but as the calling convention is specified, I'd expect this. But the local variables are a bit wonky. My question is, why wouldn't these be the same? The second call seems to produce a more compact and better aligned stack. Looking at the ASM is unenlightening (at least to me), as the variable addresses are still aliased there. So I guess this is really a question about the assembler itself allocates the stack to local variables. I realise that any specific answer is likely to be platform specific. I'm more interested in a general explanation unless this quirk really is platform specific. For the record though, I'm compiling with VS2010 on a 64bit Intel machine.

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  • Listening UDP or switch to TCP in a MFC application

    - by Alexander.S
    I'm editing a legacy MFC application, and I have to add some basic network functionalities. The operating side has to receive a simple instruction (numbers 1,2,3,4...) and do something based on that. The clients wants the latency to be as fast as possible, so naturally I decided to use datagrams (UDP). But reading all sorts of resources left me bugged. I cannot listen to UDP sockets (CAsyncSocket) in MFC, it's only possible to call Receive which blocks and waits. Blocking the UI isn't really a smart. So I guess I could use some threading technique, but since I'm not all that experienced with MFC how should that be implemented? The other part of the question is should I do this, or revert to TCP, considering reliability and implementation issues. I know that UDP is unreliable, but just how unreliable is it really? I read that it is up to 50% faster, which is a lot for me. References I used: http://msdn.microsoft.com/en-us/library/09dd1ycd(v=vs.80).aspx

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  • What's the meaning of the angle brackets on LINQ methods in Intellisense? (Contains<>, Count<>, Dis

    - by user312758
    They usually involve generics. But some methods with generics don't have them, and not all extension methods have them. They've just "been there" since day one, we've all seen them; but I realized I still don't know what they mean, and I can't find the answer anywhere. Now it's really bugging me. Google just turns up results that are about XML, etc. Is this officially documented anywhere? Thanks. EDIT: Well that's just great. Since I just created an account to make my first Stack Overflow post, to get an answer for this burning question; I'm not allowed to post my pretty Intellisense picture, or create a new tag "angle-brackets". I love Stack Overflow, but... what a welcome! Maybe my problem is that they aren't actually called "angle brackets"... ?? Anyway, I guess if you really want to see my beautiful screenshot you could manually go to: http://www.freeimagehosting.net/uploads/6a6c2f3268.png Bump me up please so I can include it in the post, thanks. ;)

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  • Not able to kill bad kernel running on NVIDIA GPU

    - by arvindkgs
    Hi, I am in a real fix. Please help. Its urgent. I have a host process that spawns multiple host(CPU) threads. These threads in turn call the CUDA kernel. These CUDA kernels are written by external users. So it might be bad kernels that enter infinite loop. In order to overcome this I have put a time-out of 2 mins that will kill the corresponding CPU thread. Will killing the CPU thread also kill the kernel running on the GPU? As far as what I have tested it does'nt. How can I also kill all the threads currently running in the GPU? Thanks, Arvind

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  • AIMA in disgrace?

    - by lmsasu
    Hi, according to some reviews on Amazon, the AIMA 3rd Edition is quite a disappointment... minor update not worth the money. In your opinion, which is then a more suitable introductory textbook on artificial intelligence?

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  • Breakpoint when variable takes on a certain value.

    - by Mick
    I have something analogous to the following code... void function(int x) { // complicated operation on x blah blah } It all appears to be working fine except when x happens to be a particular value, say "273". But x being 273 is a rare event, 99.999% of the time it is some other value. Now I wish to observe the events when this function is called with x=273, so I would like to insert a breakpoint that gets hit only with x is that value. Perhaps I could do it like this: void function(int x) { if (x == 273) { // put breakpoint on this line. } // complicated operation on x blah blah } The problem is that presumably the compiler will optimise away this "if" statement because it doesn't do anything. So my question is what should I put within the "if" statement to to make sure it gets compiled in to something... or should I be tracing the x==273 case in some completely different way.

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  • "Directly accessing" return values without referencing

    - by undocumented feature
    Look at this ruby example: puts ["Dog","Cat","Gates"].1 This will output Cat as ruby allows me to directly access the "anonymous" array created. If I try this in PHP, however: echo array("Dog","Cat,"Gates")[1] This won't work. What is this called, not only concerning arrays but all functions? Where else is it possible? Feel free to change the question title when you know how this "feature" is called.

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  • Reason for not properly closed socket?

    - by gc
    Here is what I am trying to do: The server sends message to connected clients when new messages are available. The client, on the other hand, when connected, tries to send a message to the server using send() and then receive message using recv(), right after that, the client calls close() to close the connection. Sometimes, after the client finishes, the server tries to receive message from client will result in a 104 - "connection reset by peer" error. When this happens, Wireshark reveals that the last two segments sent by the client is: 1. an ACK acknowledging the receipt of the message sent by the server 2. a RST/ACK No FIN is sent by the client. Why is this happening and how can I close the socket "properly" at the client?

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  • Picking the right language

    - by simion
    I am a student at University so my experience is limited, hence the question. If someone says to you, here is a task to code, what are you looking at in order to choose the language or paradigm in which you will do it in? Hope the question makes sense?

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  • Use of unassigned local variable 'xxx'

    - by Tomislav
    I'm writing a database importer from our competitors to ours database:) I have a code generator which create Methods form import to our database like public void Test_Import_Customer_1() // variables string conn; string sqlSelect; string sqlInsert; int extID; string name; string name2; DateTime date_inserted; sqlSelect="select id,name,date_inserted from table_competitors_1"; oledbreader reader = new GetOledbRader(sqlString,conn); while (reader.read()) { name=left((string)myreader["name"],50); //limitation of my field date_inserted=myreader["date_inserted"]; sqlInsert=string.Format("insert into table(name,name2,date_inserted)values '{0}', '{1}', {2})",name,name2,date_inserted); //here is the problem name2 "Use of unassigned local variable" ExecuteSQL(sqlInsert) } As different companies database has different fields i can not set value to each variable and there is a big number of tables to go one variable to next. like sqlSelect_Company_1 = "select name,date_inserted from table_1"; sqlSelect_Company_2 = "select name,name2 from table_2"; is there a way to override the typing of each variable one by one with default values?

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  • Re-add missing project without having to re-add it to all projects referencing it

    - by coffeeaddict
    Lets say you open a .NET solution (mine being VS 2010) after you just moved your entire folder to some new location locally. Now one of the projects that was being referenced in that solution is not there and so when you launch VS, it naturally tells you that the project is missing and therefore as always you see the project greyed out in Solution Explorer. Ok, well I can't go re-add that project (specify a different path for where that project lives) unless I remove the missing project reference and then try to re-add it back to the solution. But how can I reassociate a project without losing all references in other projects that were referencing that missing project? Is this possible? Otherwise every time I re-add that missing project, I end up having to go through about 8 projects of mine that are referencing it and re-reference it for each one of those projects which is tedious. I guess it makes sense since each project was referencing that missing project at that old path so it would break it there as well but is there an easier way to re-associate a project and references to that missing project without having to take 10 minutes every time to re-associate it all over the place if simply the path has changed?

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  • DrawString only works in top-left part of form vb.net

    - by WillumMaguire
    Here is my code Public Class Form1 Public MyFormObject As Graphics = Me.CreateGraphics Public objFont = New System.Drawing.Font("arial", 20) Public a, b As Integer Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Randomize() For i = 1 To 10 a = CInt(Int(Rnd() * Me.Width)) b = CInt(Int(Rnd() * Me.Height)) MyFormObject.DrawString("text", objFont, System.Drawing.Brushes.Black, a, b) Next End Sub End Class As you can see, I have one button that draws the string "text" randomly in the form 10 times. My problem is that it will ONLY draw the string in the upper-left portion of the form, roughly 260x260 starting at 0,0. It literally cuts off the text if it goes beyond. Why is this? Shouldn't it work for the entire form?

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  • Avoiding explicit recursion in Haskell

    - by Travis Brown
    The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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  • Applying a function to a custom type in F#

    - by Frederik Wordenskjold
    On my journey to learning F#, I've run into a problem I cant solve. I have defined a custom type: type BinTree = | Node of int * BinTree * BinTree | Empty I have made a function which takes a tree, traverses it, and adds the elements it visits to a list, and returns it: let rec inOrder tree = seq{ match tree with | Node (data, left, right) -> yield! inOrder left yield data; yield! inOrder right | Empty -> () } |> Seq.to_list; Now I want to create a function, similar to this, which takes a tree and a function, traverses it and applies a function to each node, then returns the tree: mapInOrder : ('a -> 'b) -> 'a BinTree -> 'b BinTree This seems easy, and it probably is! But I'm not sure how to return the tree. I've tried this: let rec mapInOrder f tree = match tree with | Node(data, left, right) -> mapInOrder f left Node(f(data), left, right) mapInOrder f right | Empty -> () but this returns a unit. I havent worked with custom types before, so I'm probably missing something there!

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  • running examples in package-Ex.R failed

    - by swarna
    Hi,My name is Swarna,I'm new to R,when i was checking my package i got a error message saying "Running examples in package-Ex.R failed" and series of statement saying where error might have occurred name of the package -package flush(stderr());flush(stdout()) name: title alias keywords Can any one please help me with this. Thank you,

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  • parsing xml attribute value

    - by vbNewbie
    I have been parsing xml content using the xmlreader and cannot use the xml document but so far it works getting all elementcontent except for the attribute contents. I need to parse the link below found in the following entry; <title>XXXX UUUUUU posted a</title> <category term="NotePosted" label="Note Posted"/> <link rel="alternate" type="html" href="http://www.dfsddsfdsf.com/profile.php?id=sdfdfsfdsdfddfsfd&amp;v=wall&amp;story_dbid=dssdfasdfdasfdsafafafa"/> <source>......... <source> I need the href tag in the link attribute but it keeps coming back null. While ureader.Read If ureader.HasAttributes Then fId = ureader.GetAttribute("href") If fId.Contains("?v=wall&amp") Then fIdList.Add(fId) Exit While End If If String.IsNullOrEmpty(fId) Then fId = "NOTHING" End If End If End While

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  • Most efficient way for testing links

    - by Burnzy
    I'm currently developping an app that is going through all the files on a server and checking every single hrefs to check wether they are valid or not. Using a WebClient or a HttpWebRequest/HttpWebResponse is kinda overkilling the process because it downloads the whole page each time, which is useless, I only need to check if the link do not return 404. What would be the most efficient way? Socket seems to be a good way of doing it, however I'm not quite sure how this works. Thanks for sharing your expertise!

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