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  • Matrix multiplication using Matrix Template library (MTL 4)

    - by Lxc
    The program is as following: #include <iostream> #include <boost/numeric/mtl/mtl.hpp> using namespace mtl; int main(int argc, char* argv[]) { dense_vector<double> a(5,1.0); dense_vector<double> b(5,2.0); a * trans(b); } I want to calculate a * trans(b), but there is a compling error :C2893. Will someone help me? Thanks a lot!

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  • Force an object to be allocated on the heap

    - by Warren Seine
    A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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  • Programmatically check whether a linux kernel module exists or not at runtime

    - by dgraziotin
    I am writing a C daemon, which depends on the existence of two kernel modules in order to do its job. The program does not directly use these (or any other) modules. It only needs them to exist. Therefore, I would like to programmatically check whether these modules are already loaded or not, in order to warn the user at runtime. Before I start to do things like parsing /proc/modules or lsmod output, does a utility function already exist somewhere? Something like is_module_loaded(const char* name); I am pretty sure this has been asked before. However, I think I am missing the correct terms to search for this. Thanks!

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  • Please explain syntax rules and scope for "typedef"

    - by unknown google user
    What are the rules? OTOH the simple case seems to imply the new type is the last thing on a line. Like here Uchar is the new type. typedef unsigned char Uchar; But a function pointer is completely different. Here the new type is pFunc: typedef int (*pFunc) (int); I can't think of any other examples offhand but I have come across some very confusing usages. So are there rules or are people just suppose to know from experience that this is how it is done because they have seen it done this way before? ALSO: What is the scope of a typedef. Thanks to everyone.

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  • C# Drag and Drop Effect with Overlay/Opaque Image

    - by CallMeLaNN
    Hi, I think this would be simple question and should be asked in the pas few years but unable to google around and dont know if there is a specific keyword. In c# WinForm I want to do drag and drop but I dont want the image of DragDropEffects Move, Copy or whatever. I want to display an image with half opaque. Just like Firefox when dragging an image, you would see the image folowing the mouse pointer like a ghost :) I already Implement DoDragDrop, DragEnter and DragDrop events. I just want to customize the dragging effects with overlay image.

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  • Stringification of a macro value

    - by SF.
    I faced a problem - I need to use a macro value both as string and as integer. #define RECORDS_PER_PAGE 10 /*... */ #define REQUEST_RECORDS \ "SELECT Fields FROM Table WHERE Conditions" \ " OFFSET %d * " #RECORDS_PER_PAGE \ " LIMIT " #RECORDS_PER_PAGE ";" char result_buffer[RECORDS_PER_PAGE][MAX_RECORD_LEN]; /* ...and some more uses of RECORDS_PER_PAGE, elsewhere... */ This fails with a message about "stray #", and even if it worked, I guess I'd get the macro names stringified, not the values. Of course I can feed the values to the final method ( "LIMIT %d ", page*RECORDS_PER_PAGE ) but it's neither pretty nor efficient. It's times like this when I wish the preprocessor didn't treat strings in a special way and would process their content just like normal code. For now, I cludged it with #define RECORDS_PER_PAGE_TXT "10" but understandably, I'm not happy about it. How to get it right?

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  • When is C++ covariance the best solution?

    - by Neil Butterworth
    This question was asked here a few hours ago and made me realise that I have never actually used covariant return types in my own code. For those not sure what covariance is, it's allowing the return type of (typically) virtual functions to differ provided the types are part of the same inheritance hierarchy. For example: struct A { virtual ~A(); virtual A * f(); ... }; struct B : public A { virtual B * f(); ... }; The different return types of the two f() functions are said to be covariant. Older versions of C++ required the return types to be the same, so B would have to look like: struct B : public A { virtual A * f(); ... }; So, my question: Does anyone have a real-world example where covariant return types of virtual functions are required, or produce a superior solution to simply returning a base pointer or reference?

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  • C - add elements to struct by define

    - by CodeStepper
    I have a problem. I'm trying to add struct elements by previously defined constant. This is sample code (OpenGL+WinAPI) #define ENGINE_STRUCT \ HGLRC RenderingContext;\ HDC DeviceContext; And then: typedef struct SWINDOW { ENGINE_STRUCT HWND Handle; HINSTANCE Instance; CHAR* ClassName; BOOL Fullscreen; BOOL Active; MSG Message; } WINDOW; Is this possible? Thanks in advance.

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  • Why is it so hard to build a gtk programe without console using cmake in windows?

    - by Runner
    I'm following the tuto: http://zetcode.com/tutorials/gtktutorial/firstprograms/ It works but each time I double click on the executable,there is a console which I don't want it there. How do I get rid of that console? I tried this: add_executable(Cmd WIN32 cmd.c) But got this fatal error: MSVCRTD.lib(crtexew.obj) : error LNK2019: unresolved external symbol _WinMain@16 referenced in function ___tmainCRTStartup Cmd.exe : fatal error LNK1120: 1 unresolved externals While using gcc directly works: gcc -o Cmd cmd.c -mwindows .. I'm guessing it has something to do with the entry function: int main( int argc, char *argv[]),but why gcc works? How can I make it work with cmake?

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  • How can you get the first digit in an int (C#)?

    - by Dinah
    In C#, what's the best way to get the 1st digit in an int? The method I came up with is to turn the int into a string, find the 1st char of the string, then turn it back to an int. int start = Convert.ToInt32(curr.ToString().Substring(0, 1)); While this does the job, it feels like there is probably a good, simple, math-based solution to such a problem. String manipulation feels clunky. Edit: irrespective of speed differences, mystring[0] instead of Substring() is still just string manipulation

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  • How to receive a arg from command line in C

    - by 115599yy
    Hi everyone: I want to write a program to receive a argument from command line. It's like a kind of atof(). There my program goes: 9 char s[] = "3.1415e-4"; 10 if (argc == 1) { 11 printf("%e\n",atof(s)); 12 } 13 else if (argc == 2) { 14 //strcpy(s, argv[1]); 15 printf("%e\n",atof(argv[1])); 16 } 1.should I just use argv[1] for the string to pass to my atof(), or, put it into s[]? 2.If I'd better put it in s[], is there some build-in function to do this "put" work? maybe some function like strcpy()?? thanks.

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  • how to find last version no from a list<> in C#

    - by Rohit
    I have a entity class RenderingTemplates. Inside this i have a property List which holds all versions of rendering template. RenderingTemplateVersion has a property VersionName which stores version name as "Version 1.0". I am creating a new version and want to find last version no.so that i can append it by 1 and make new VersionName as "Version 2.0". To accomplish this i have LatestVersion = template.RenderingTemplateVersionList.OrderByDescending(e => e.VersionName.Split(new char[] { ' ', '.' })[1]).First() LatestVersion is a integer. How to convert this to integer.Please help or suggest some other way.

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  • Are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ?

    - by snowflake
    I consider a self-described / auto-descriptive service as a good thing in a SOA architecture, since (almost) everything you know to call the service is present in the service contract (such a WSDL). Sample of a non self-described service for me is Facebook Query Language (FQL http://wiki.developers.facebook.com/index.php/FQL), or any web service exchanging XML flow in a one String parameter for then parsing XML and performing treatments. Last ones seem further more technically decoupled, since technically you can switch implementations without technical impact on the caller, handling compatibility between implementations/versions at a business level. On the other side, having no strong interface (diluted into the service and its version), make the service tightly coupled to the existing implementation (more difficulty to interchange the service and to ensure perfect compatibility). This question is related to http://stackoverflow.com/questions/2503071/how-to-implement-loose-coupling-with-a-soa-architecture So, are self-described / auto-descriptive services loosely or tightly coupled in a SOA architecture ? What are the impacts regarding ESBs ? Any pointer will be appreciated.

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  • How can i use listDictionary?

    - by Phsika
    i can fill my listdictinary but, if running error returns to me in " foreach (string ky in ld.Keys)"(invalid operation Exception was unhandled) Error Detail : After creating a pointer to the list of sample collection has been changed. C# ListDictionary ld = new ListDictionary(); foreach (DataColumn dc in dTable.Columns) { MessageBox.Show(dTable.Rows[0][dc].ToString()); ld.Add(dc.ColumnName, dTable.Rows[0][dc].ToString()); } foreach (string ky in ld.Keys) if (int.TryParse(ld[ky].ToString(), out QuantityInt)) ld[ky] = "integer"; else if(double.TryParse(ld[ky].ToString(), out QuantityDouble)) ld[ky]="double"; else ld[ky]="nvarchar";

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  • Query on the scope of local variables in C

    - by darkie15
    All, Consider the following code: void func(void) { int a; printf ("%d", a); } int main(int argc, char **argv) { int a = 3; func(); printf("%d", a); } According to my understanding, the output should be: <junk value><3> Can anyone please confirm my understanding? My basic query is, does the compiler refer to the outer scope for a variable that has been declared but not defined? Regards, darkie

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  • Using methods on 2 input files - 2nd is printing multiple times - Java

    - by Aaa
    I have the following code to read in text, store in a hashmap as bigrams (with other methods to sort them by frequency and do v. v. basic additive smoothing. I had it working great for one language input file (english) and then I want to expand it for the second language input file (japanese - doens;t matter what it is I suppose) using the same methods but the Japanese bigram hashmap is printing out 3 times in a row with diff. values. I've tried using diff text in the input file, making sure there are no gaps in text etc. I've also put print statements at certain places in the Japanese part of the code to see if I can get any clues but all the print statements are printing each time so I can't work out if it is looping at a certain place. I have gone through it with a fine toothcomb but am obviously missing something and slowly going crazy here - any help would be appreciated. thanks in advance... package languagerecognition2; import java.lang.String; import java.io.InputStreamReader; import java.util.*; import java.util.Iterator; import java.util.List.*; import java.util.ArrayList; import java.util.AbstractMap.*; import java.lang.Object; import java.io.*; import java.util.Enumeration; import java.util.Arrays; import java.lang.Math; public class Main { /** public static void main(String[] args) { //training English ----------------------------------------------------------------- File file = new File("english1.txt"); StringBuffer contents = new StringBuffer(); BufferedReader reader = null; try { reader = new BufferedReader(new FileReader(file)); String test = null; //test = reader.readLine(); // repeat until all lines are read while ((test = reader.readLine()) != null) { test = test.toLowerCase(); char[] charArrayEng = test.toCharArray(); HashMap<String, Integer> hashMapEng = new HashMap<String, Integer>(bigrams(charArrayEng)); LinkedHashMap<String, Integer> sortedListEng = new LinkedHashMap<String, Integer>(sort(hashMapEng)); int sizeEng=sortedListEng.size(); System.out.println("Total count of English bigrams is " + sizeEng); LinkedHashMap<String, Integer> smoothedListEng = new LinkedHashMap<String, Integer>(smooth(sortedListEng, sizeEng)); //print linkedHashMap to check values Set set= smoothedListEng.entrySet(); Iterator iter = set.iterator ( ) ; System.out.println("Beginning English"); while ( iter.hasNext()) { Map.Entry entry = ( Map.Entry ) iter.next ( ) ; Object key = entry.getKey ( ) ; Object value = entry.getValue ( ) ; System.out.println( key+" : " + value); } System.out.println("End English"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader != null) { reader.close(); } } catch (IOException e) { e.printStackTrace(); } } //End training English----------------------------------------------------------- //Training japanese-------------------------------------------------------------- File file2 = new File("japanese1.txt"); StringBuffer contents2 = new StringBuffer(); BufferedReader reader2 = null; try { reader2 = new BufferedReader(new FileReader(file2)); String test2 = null; //repeat until all lines are read while ((test2 = reader2.readLine()) != null) { test2 = test2.toLowerCase(); char[] charArrayJap = test2.toCharArray(); HashMap<String, Integer> hashMapJap = new HashMap<String, Integer>(bigrams(charArrayJap)); //System.out.println( "bigrams stage"); LinkedHashMap<String, Integer> sortedListJap = new LinkedHashMap<String, Integer>(sort(hashMapJap)); //System.out.println( "sort stage"); int sizeJap=sortedListJap.size(); //System.out.println("Total count of Japanese bigrams is " + sizeJap); LinkedHashMap<String, Integer> smoothedListJap = new LinkedHashMap<String, Integer>(smooth(sortedListJap, sizeJap)); System.out.println( "smooth stage"); //print linkedHashMap to check values Set set2= smoothedListJap.entrySet(); Iterator iter2 = set2.iterator(); System.out.println("Beginning Japanese"); while ( iter2.hasNext()) { Map.Entry entry2 = ( Map.Entry ) iter2.next ( ) ; Object key = entry2.getKey ( ) ; Object value = entry2.getValue ( ) ; System.out.println( key+" : " + value); }//end while System.out.println("End Japanese"); }//end while }//end try catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { if (reader2 != null) { reader2.close(); } } catch (IOException e) { e.printStackTrace(); } } //end training Japanese--------------------------------------------------------- } //end main (inner)

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  • Regular Expression to match unlimited number of options

    - by Pekka
    I want to be able to parse file paths like this one: /var/www/index.(htm|html|php|shtml) into an ordered array: array("htm", "html", "php", "shtml") and then produce a list of alternatives: /var/www/index.htm /var/www/index.html /var/www/index.php /var/www/index.shtml Right now, I have a preg_match statement that can split two alternatives: preg_match_all ("/\(([^)]*)\|([^)]*)\)/", $path_resource, $matches); Could somebody give me a pointer how to extend this to accept an unlimited number of alternatives (at least two)? Just regarding the regular expression, the rest I can deal with. The rule is: The list needs to start with a ( and close with a ) There must be one | in the list (i.e. at least two alternatives) Any other occurrence(s) of ( or ) are to remain untouched.

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  • What is the role of asserts in C++ programs that have unit tests?

    - by lhumongous
    Greetings, I've been adding unit tests to some legacy C++ code, and I've run into many scenarios where an assert inside a function will get tripped during a unit test run. A common idiom that I've run across is functions that take pointer arguments and immediately assert if the argument is NULL. I could easily get around this by disabling asserts when I'm unit testing. But I'm starting to wonder if unit tests are supposed to alleviate the need for runtime asserts. Is this a correct assessment? Are unit tests supposed to replace runtime asserts by happening sooner in the pipeline (ie: the error is caught in a failing test instead of when the program is running). On the other hand, I don't like adding soft fails to code (eg: if(param == NULL) return false;). A runtime assert at least makes it easier to debug a problem in case a unit test missed a bug. Thanks!

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  • hierarchical html listbox with mimicking file explorer level folding

    - by collapsar
    hello everybody, i'm looking for a technique to adapt a html listbox to hierarchical content with an unlimited number of levels ( const 1 would be sufficient ). hierarchy levels should be collapsible as in the usual file explorer views. the html listbox behaviour should be preserved / mimicked as comprehensively as possible. do you have a hint on where to find or how to implement this ? jquery solutions are fine. firefox 3.5+, ie 8+, safari 5 must be supported; opera 11, chrome 9 would be nice. as far as i understand the issue, listbox contents are rendered inside their own browser window sporting none of the standard window adornments. a hint on how to obtain a handle on this window in js would be a sufficient starting point, as well as correcting me in case i misconceived the browser behaviour. thanks in advance for your efforts, best regards, carsten

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  • When do I need to deallocate memory? C++

    - by extintor
    I am using this code inside a class to make a webbrowser control visit a website: void myClass::visitWeb(const char *url) { WCHAR buffer[MAX_LEN]; ZeroMemory(buffer, sizeof(buffer)); MultiByteToWideChar(CP_ACP, MB_ERR_INVALID_CHARS, url, strlen(url), buffer, sizeof(buffer)-1); VARIANT vURL; vURL.vt = VT_BSTR; vURL.bstrVal = SysAllocString(buffer); // webbrowser navigate code... VariantClear(&vURL); } Do I need to do some memory deallocation here?, I see vURL is being deallocated by VariantClear but should I deallocate memory for buffer? I've been told that in another bool I have in the same app I shouldn't deallocate anything because everything clear out when the bool return true/false, but what happens on this void?

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  • SQL Server 2008 Stored Procedure

    - by user238319
    I cannot store the date data type variables using stored procedure. My code is: ALTER PROCEDURE [dbo].[Access1Register] -- Add the parameters for the stored procedure here @MobileNumber int, @CitizenName varchar(50), @Dob char(8), @VerificationCode int AS BEGIN -- SET NOCOUNT ON added to prevent extra result sets from -- interfering with SELECT statements. SET NOCOUNT ON; -- Insert statements for procedure here select CAST(@dob As DATE) Insert Into Access1 (MobileNo,CitizenName,Dob,VerificationCode) values(@MobileNumber,@CitizenName,@Dob,@VerificationCode) go If I exec this procedure it is executing, but there is an error occured in the date type variable. It's raising the error as invalid item '-'.

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  • Best way to track impressions/clicks in a bespoke advertisement system?

    - by Martin Bean
    I've been asked to create a bespoke advertisement system despite suggesting open source alternatives such as OpenX and DoubleClick for Publishers (the former Google Ad Manager). I've got the basics of the system set up, i.e. uploading creatives, creating positions and a mechanism to place creatives within positions; however, the area I'm stuck with is impression and click tracking. At the moment an impression and click is stored with the creative, but this then means impressions/clicks can't be queried. For example, we can't find how many impressions were in position x between date y and date z. How would I go about storing that kind of data? My theory was store the creative ID, position ID and timestamp in a database table, but given the amount of traffic the site has this would produce a very large database very quickly. If any one could give me a pointer or two, that would be great.

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  • How to name variables which are structs

    - by evilpie
    Hello, i often work on private projects using the WinApi, and as you might know, it has thousands of named and typedefed structs like MEMORY_BASIC_INFORMATION. I will stick to this one in my question, what still is preferred, or better when you want to name a variable of this type. Is there some kind of style guide for this case? For example if i need that variable for the VirtualQueryEx function. Some ideas: MEMORY_BASIC_INFORMATION memoryBasicInformation; MEMORY_BASIC_INFORMATION memory_basic_information; Just use the name of the struct non capitalized and with or without the underlines. MEMORY_BASIC_INFORMATION basicInformation; MEMORY_BASIC_INFORMATION information; Short form? MEMORY_BASIC_INFORMATION mbi; I often see this style, using the abbreviation of the struct name. MEMORY_BASIC_INFORMATION buffer; VirtualQueryEx defines the third parameter lpBuffer (where you pass the pointer to the struct), so using this name might be an idea, too. Cheers

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  • How to create an image from canvas data?

    - by Jakub Hampl
    In my application I am trying to save an arbitrary part of a rendered HTML canvas to an image file. In my Javascript I call ctx.getImageData(x, y, w, h) and pass the resulting object to my macruby code (though if you know a solution in objc I am also very interested). There I'm trying to create a NSBitmapImageRep object so that I can then save to an image format the user desires. This is my code so far (the function gets a WebScriptObject as it's argument): def setimagedata(d) w = d.valueForKey("width").to_i h = d.valueForKey("height").to_i data = Pointer.new(:char, d.valueForKey("data").valueForKey("length").to_i) d.valueForKey("data").valueForKey("length").to_i.times do |i| data[i] = d.valueForKey("data").webScriptValueAtIndex(i).to_i end puts "data complete" # get's called @exported_image = NSBitmapImageRep.alloc.initWithBitmapDataPlanes(data, pixelsWide: w, pixelsHigh:h, bitsPerSample: 32, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSCalibratedRGBColorSpace, bitmapFormat: NSAlphaNonpremultipliedBitmapFormat, bytesPerRow: 0, bitsPerPixel: 0) puts "done" # doesn't get called end The code doesn't seem to get through the initWithBitmapDataPlanes function but gives no error. My question is: what am I doing wrong? Is this approach reasonable (if not, what would be better?).

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  • UML binary association aggregatee has access to aggregator

    - by user314172
    Firstly, I'd like to thank those who answered my previous question ages ago. Currently I'm engaging more in the design phase UMLs, as this is my first medium scale deployment I'm entrusted with. This is extremely simple, but it bugs me so. If (Component) owns (Manager of Component), and (Manager of Component) has a reference to (Component) through which it manages it; how do you fully describe the relationship? I know it is aggregative, but how do you describe (Manager of Component) possessing a reference/pointer to the (Component) that physically owns the (Manager of Component) ? Example: Lidar owns a LidarManager

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