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• Why is FxCop warning about an overflow (CA2233) in this C# code?

  - by matt

  I have the following function to get an int from a high-byte and a low-byte: public static int FromBytes(byte high, byte low) { return high * (byte.MaxValue + 1) + low; } When I analyze the assembly with FxCop, I get the following critical warning: CA2233: OperationsShouldNotOverflow Arithmetic operations should not be done without first validating the operands to prevent overflow. I can't see how this could possibly overflow, so I am just assuming FxCop is being overzealous. Am I missing something? And what steps could be taken to correct what I have (or at least make the FxCop warning go away!)?

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• Retrieve data from .dat file.

  - by Zach

  We have an application which requires us to read data from a file (.dat) dynamically using deserialization. We are actually getting first object and it throws null pointer exception when we are accessing other objects using a "for" loop. File file=null; FileOutputStream fos=null; BufferedOutputStream bos=null; ObjectOutputStream oos=null; try{ file=new File("account4.dat"); fos=new FileOutputStream(file,true); bos=new BufferedOutputStream(fos); oos=new ObjectOutputStream(bos); oos.writeObject(m); System.out.println("object serialized"); amlist=new MemberAccountList(); oos.close(); } catch(Exception ex){ ex.printStackTrace(); } Reading objects: try{ MemberAccount m1; file=new File("account4.dat");//add your code here fis=new FileInputStream(file); bis=new BufferedInputStream(fis); ois=new ObjectInputStream(bis); System.out.println(ois.readObject()); while(ois.readObject()!=null){ m1=(MemberAccount)ois.readObject(); System.out.println(m1.toString()); }/mList.addElement(m1); // Here we have the issue throwing null pointer exception Enumeration elist=mList.elements(); while(elist.hasMoreElements()){ obj=elist.nextElement(); System.out.println(obj.toString()); }/ } catch(ClassNotFoundException e){ } catch(EOFException e){ System.out.println("end"); } catch(Exception ex){ ex.printStackTrace(); }

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• Simulating pass by reference for an array in Java

  - by Leif Andersen

  I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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• Position an icon on the right in the middle of a list item

  - by Andy

  I have the following code which prints an img if the current page is selected. The issue i have is if the list item is a varied height i cant position it in the middle of the list item on the far right... <li><?php echo $child->link($child->title); ?><?php echo (url_start_with($child->url) ? '<img src="images/ico-arrow.png" class="pointer">': null); ?></li> how can i ammend the "TOP" so that it will position itself vertically no matter what the height using css #bf-fest-list li { margin:0; padding:5px 25px; position:relative; } #bf-fest-list li a:hover { color:#ec1c23; text-decoration:none; } #bf-fest-list li.current { background:#a0a1a4; padding:10px 25px; } #bf-fest-list li.current a { color:#FFF; } #bf-fest-list li .pointer { position:absolute; top:10px; left:233px; }

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• Simulating pass by reference for an array reference (i.e. a reference to a reference) in Java

  - by Leif Andersen

  I was wondering, in java, is it possible to in anyway, simulate pass by reference for an array? Yes, I know the language doesn't support it, but is there anyway I can do it. Say, for example, I want to create a method that reverses the order of all the elements in an array. (I know that this code snippet isn't the best example, as there is a better algorithms to do this, but this is a good example of the type of thing I want to do for more complex problems). Currently, I need to make a class like this: public static void reverse(Object[] arr) { Object[] tmpArr = new Object[arr.length]; count = arr.length - 1; for(Object i : arr) tmpArr[count--] = i; // I would like to do arr = tmpArr, but that will only make the shallow // reference tmpArr, I would like to actually change the pointer they passed in // Not just the values in the array, so I have to do this: count = arr.length - 1; for(Object i : tmpArr) arr[count--] = i; return; } Yes, I know that I could just swap the values until I get to the middle, and it would be much more efficient, but for other, more complex purposes, is there anyway that I can manipulate the actual pointer? Again, thank you.

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• Where my memory is alloced, Stack or Heap, Can I find it at Run-time?

  - by AKN

  I know that memory alloced using new, gets its space in heap, and so we need to delete it before program ends, to avoid memory leak. Let's look at this program... Case 1: char *MyData = new char[20]; _tcscpy(MyData,"Value"); . . . delete[] MyData; MyData = NULL; Case 2: char *MyData = new char[20]; MyData = "Value"; . . . delete[] MyData; MyData = NULL; In case 2, instead of allocating value to the heap memory, it is pointing to a string literal. Now when we do a delete it would crash, AS EXPECTED, since it is not trying to delete a heap memory. Is there a way to know where the pointer is pointing to heap or stack? By this the programmer Will not try to delete any stack memory He can investigate why does this ponter, that was pointing to a heap memory initially, is made to refer local literals? What happened to the heap memory in the middle? Is it being made to point by another pointer and delete elsewhere and all that?

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• AWK If/ElseConditional Problem

  - by neversaint

  I have a data that looks like this: foo foo scaffold_7 1 4845 6422 4845 bar bar scaffold_7 -1 14689 16310 16310 What I want to do is to process the above lines where I just want to print column 1,2,3, 7 and one more column after 7th. But with condition when printing column 7 onwards. Below is my awk script: awk '{ if ($4=="+") { {end=$6-$5}{print $1 "\t" $2 "\t" $3 "\t" $4 "\t" $7 "\t" end+$7} } else {end=$6-$5}{print $1 "\t" $2 "\t" $3 "\t" $4 "\t" $7-end "\t" $7} }' But why it doesn't achieve the desired result like this? foo foo scaffold_7 1 4845 6422 bar bar scaffold_7 -1 14689 16310 Note that the arithmetic (e.g. $7-end or end+$7) is a must. So we can't just swap column from input file. Furthermore this AWK will be inside a bash script.

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• Is there a way to put relationships/contraints into CSS?

  - by hekevintran

  In every design tool or art principle I've heard of, relationships are a central theme. By relationships I mean the thing you can do in Adobe Illustrator to specify that the height of one shape is equal to half the height of another. You cannot express this information in CSS. CSS hard-codes all values. Using a language like LESS that allows variables and arithmetic you can get closer to relationships but it's still a CSS variant. This inability in my mind is the biggest problem with CSS. CSS is supposed to be a language that describes the visual component of a Web page but it ignores relationships and contraints, ideas that are at the core of art. How possible is it to imagine a new Web design language that can express relationships and contraints that can be implemented in JavaScript using the current CSS properties?

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• Opacity CSS not working in IE8

  - by Alistair Christie

  I'm using CSS to indicate the trigger text for a jQuery slide-down section: i.e. when you hover over the trigger text the cursor changes to a pointer and the opacity of the trigger text is reduced to indicate that the text has a click action. This works fine in Firefox and Chrome, but in IE8 the opacity doesn't change. I've tried a variety of CSS settings without any success. For example HTML: <h3 class="slidedownTrigger">This is the trigger text</h3> CSS: .slidedownTrigger {     cursor: pointer;     -ms-filter: “progid:DXImageTransform.Microsoft.Alpha(Opacity=75)”;     filter: alpha(opacity=75);     -khtml-opacity: 0.75;     -moz-opacity: 0.75;     opacity: 0.75; } What's stopping IE changing the opacity? Note: I've tried this on a variety of different elements, swapping round the order of the CSS statements, and just using the IE ones on their own. I've also tried using -ms-filter: "alpha(opacity=75)"; but with no success. I've run out of things to try to get opacity modification working in IE8. Any ideas?

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• Convert C++Builder AnsiString to std::string via boost::lexical_cast

  - by David Klein

  For a school assignment I have to implement a project in C++ using Borland C++ Builder. As the VCL uses AnsiString for all GUI Components I have to convert all of my std::strings to AnsiString for the sake of displaying. std::string inp = "Hello world!"; AnsiString outp(inp.c_str()); works of course but is a bit tedious to write and code duplication I want to avoid. As we use Boost in other contexts I decided to provide some helper functions go get boost::lexical_cast to work with AnsiString. Here is my implementation so far: std::istream& operator>>(std::istream& istr, AnsiString& str) { istr.exceptions(std::ios::badbit | std::ios::failbit | std::ios::eofbit); std::string s; std::getline(istr,s); str = AnsiString(s.c_str()); return istr; } In the beginning I got Access Violation after Access Violation but since I added the .exceptions() stuff the picture gets clearer. When the conversion is performed I get the following Exception: ios_base::eofbit set [Runtime Error/std::ios_base::failure] Does anyone have an idea how to fix it and can explain why the error occurs? My C++ experience is very limited. The conversion routine the other way round would be: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); return ostr; } Maybe someone will spot an error here too :) With best regards! Edit: At the moment I'm using the edited version of Jem, it works in the beginning. After a while of using the programm the Borland Codeguard mentions some pointer arithmetic in already freed regions. Any ideas how this could be related? The Codeguard log (I'm using the german version, translations marked with stars): ------------------------------------------ Fehler 00080. 0x104230 (r) (Thread 0x07A4): Zeigerarithmetik in freigegebenem Speicher: 0x0241A238-0x0241A258. **(pointer arithmetic in freed region)** | d:\program files\borland\bds\4.0\include\dinkumware\sstream Zeile 126: | { // not first growth, adjust pointers | _Seekhigh = _Seekhigh - _Mysb::eback() + _Ptr; |> _Mysb::setp(_Mysb::pbase() - _Mysb::eback() + _Ptr, | _Mysb::pptr() - _Mysb::eback() + _Ptr, _Ptr + _Newsize); | if (_Mystate & _Noread) Aufrufhierarchie: **(stack-trace)** 0x00411731(=FOSChampion.exe:0x01:010731) d:\program files\borland\bds\4.0\include\dinkumware\sstream#126 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 0x004080C9(=FOSChampion.exe:0x01:0070C9) D:\Projekte\Schule\foschamp\lib\boost_1_34_1\boost/lexical_cast.hpp#151 Objekt (0x0241A238) [Größe: 32 Byte] war erstellt mit new **(Object was created with new)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 28: | _Ty _FARQ *_Allocate(_SIZT _Count, _Ty _FARQ *) | { // allocate storage for _Count elements of type _Ty |> return ((_Ty _FARQ *)::operator new(_Count * sizeof (_Ty))); | } | Aufrufhierarchie: **(stack-trace)** 0x0040ED90(=FOSChampion.exe:0x01:00DD90) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#28 0x0040E194(=FOSChampion.exe:0x01:00D194) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#143 0x004115CF(=FOSChampion.exe:0x01:0105CF) d:\program files\borland\bds\4.0\include\dinkumware\sstream#105 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 Objekt (0x0241A238) war Gelöscht mit delete **(Object was deleted with delete)** | d:\program files\borland\bds\4.0\include\dinkumware\xmemory Zeile 138: | void deallocate(pointer _Ptr, size_type) | { // deallocate object at _Ptr, ignore size |> ::operator delete(_Ptr); | } | Aufrufhierarchie: **(stack-trace)** 0x004044C6(=FOSChampion.exe:0x01:0034C6) d:\program files\borland\bds\4.0\include\dinkumware\xmemory#138 0x00411628(=FOSChampion.exe:0x01:010628) d:\program files\borland\bds\4.0\include\dinkumware\sstream#111 0x00411183(=FOSChampion.exe:0x01:010183) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#465 0x0040933D(=FOSChampion.exe:0x01:00833D) d:\program files\borland\bds\4.0\include\dinkumware\streambuf#151 0x00405988(=FOSChampion.exe:0x01:004988) d:\program files\borland\bds\4.0\include\dinkumware\ostream#679 0x00405759(=FOSChampion.exe:0x01:004759) D:\Projekte\Schule\foschamp\src\Server\Ansistringkonverter.h#31 ------------------------------------------ Ansistringkonverter.h is the file with the posted operators and line 31 is: std::ostream& operator<<(std::ostream& ostr,const AnsiString& str) { ostr << (str.c_str()); **(31)** return ostr; } Thanks for your help :)

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• How should I go about creating a point system for users like SO and yahoo answers?(PHP)

  - by ggfan

  I am creating a voting system for a Q&A site project in which if a user asks a question, he/she losses -5 points; answer a question +5, vote a question +1, etc. (kind of like SO and yahoo answers) --To create the basic arithmetic, I have a "users_points" table that relates the user_id and their total points. +---+---------+ | 1 | 100 | +---+---------+ | 2 | 54 | +---+---------+ --Basically if the users does certain task, it would + or - the points. How do I prevent users from say voting an answer up 100 times. ex: I want a user to be only able to vote once per question, etc.

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• MATLAB for kids?

  - by yuk

  My seven-years old expresses large interest in computers (well, who doesn't? :). Since I'm mostly program in MATLAB, I'm thinking why not to teach him MATLAB. We did a small project with him (he had to solve as many simple arithmetic problems as possible in a limited time) and he get pretty excited. I coded, he watched and then tested. He also likes to do create interesting graphics and simple animations. So, what's next? I would appreciate any ideas for interesting projects, games, graphics? What math concepts he has to understand to program in MATLAB? Or may be you would say it's too early and we should start with something like Logo, Scratch or Alice?

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• OpenCV SVD Matrix format.

  - by Rick

  I currently have a set of 2D Cartesian coordinates e.g. {(1,3), (2,2), (3,4)} Which will be put into a 2D array, to perform SVD properly would the matrix be put together such that the coordinates form the columns or the rows e.g. 1 3 2 2 3 4 or 1 2 3 3 2 4 I have been doing a little trial and error comparing to examples of SVD I have found online, the resulting matrix usually seems to be negated, with some of the values shuffled around. To clarify further if I had a matrix E which was MxN as shown here http://upload.wikimedia.org/wikipedia/commons/b/bb/Matrix.svg To define the matrix as a 2D array would it be Array[M][N] or Array[N][M] I am assuming this actually matters due to matrix arithmetic not being commutative? Can anyone actually verify this?

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• Save QList<int> to QSettings

  - by Tobias

  Hello, I want to save a QList<int> to my QSettings without looping through it. I know that I could use writeArray() and a loop to save all items or to write the QList to a QByteArray and save this but then it is not human readable in my INI file.. Currently I am using the following to transform my QList<int> to QList<QVariant>: QList<QVariant> variantList; //Temp is the QList<int> for (int i = 0; i < temp.size(); i++) variantList.append(temp.at(i)); And to save this QList<Variant> to my Settings I use the following code: QVariant list; list.setValue(variantList); //saveSession is my QSettings object saveSession.setValue("MyList", list); The QList is correctly saved to my INI file as I can see (comma seperated list of my ints) But the function crashes on exit. I already tried to use a pointer to my QSettings object instead but then it crashes on deleting the pointer ..

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• C function const multidimensional-array argument strange warning

  - by rogi

  Ehllo, I'm getting some strange warning about this code: typedef double mat4[4][4]; void mprod4(mat4 r, const mat4 a, const mat4 b) { /* yes, function is empty */ } int main() { mat4 mr, ma, mb; mprod4(mr, ma, mb); } gcc output as follows: $ gcc -o test test.c test.c: In function 'main': test.c:13: warning: passing argument 2 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double (*)[4]' but argument is of type 'double (*)[4]' test.c:13: warning: passing argument 3 of 'mprod4' from incompatible pointer type test.c:4: note: expected 'const double ()[4]' but argument is of type 'double ()[4]' defining the function as: void mprod4(mat4 r, mat4 a, mat4 b) { } OR defining matrices at main as: mat4 mr; const mat4 ma; const mat4 mb; OR calling teh function in main as: mprod4(mr, (const double(*)[4])ma, (const double(*)[4])mb); OR even defining mat4 as: typedef double mat4[16]; make teh warning go away. Wat is happening here? Am I doing something invalid? gcc version is 4.4.3 if relevant. Thanks for your attention.

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• sIFR - getting a:hover to work in navigation list

  - by HudRom

  Hi, I am currently struggling with sIFR and a:hover. My problem site is hosted at http://irene.huditsch.info I have the following HTML code: <body id="irene-huditsch-info"> <div id="header"> <h1>Irene Huditsch</h1> <div id="top-nav"> <ul> <li id="impressum"> <a href="impressum.html" rel="index">Impressum</a> </li> <li id="kontakt"> <a href="kontakt.html">Kontakt</a> </li> </ul> </div> ... My sIFR-config.js looks like: sIFR.replace(braganza, { selector: 'div#top-nav a', css: '.sIFR-root { background-color: transparent; color: #FFFFFF; line-height: 13px; font-size: 11px; text-decoration: underline; cursor: pointer; } .sIFR-root:hover { color: #592b02; }', wmode: 'transparent' }); But the hover doesn't take effect. I tried different solution with no success either. When I write sIFR.replace(braganza, { selector: 'div#top-nav li', css: 'a { background-color: transparent; color: #FFFFFF; line-height: 13px; font-size: 11px; text-decoration: underline; cursor: pointer; } a:hover { color: #592b02; }', wmode: 'transparent' }); (which seems logical to me), the list items are not rendered at all. Could you please give me an advice how to do it correctly with the structure given? Thanks, Roman

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• Declaration of arrays before "normal" variables in c?

  - by bjarkef

  Hi We are currently developing an application for a msp430 MCU, and are running into some weird problems. We discovered that declaring arrays withing a scope after declaration of "normal" variables, sometimes causes what seems to be undefined behavior. Like this: foo(int a, int *b); int main(void) { int x = 2; int arr[5]; foo(x, arr); return 0; } foo sometimes is passed a pointer as the second variable, that does not point to the arr array. We verify this by single stepping through the program, and see that the value of the arr variable in the main scope is not the same as the value of the b pointer variable in the foo scope. And no, this is not really reproduceable, we have just observed this behavior once in a while. Changing the example seems to solve the problem, like this: foo(int a, int *b); int main(void) { int arr[5]; int x = 2; foo(x, arr); return 0; } Does anybody have any input or hints as to why we experience this behavior? Or similar experiences? The MSP430 programming guide specifies that code should conform to the ANSI C89 spec. and so I was wondering if it says that arrays has to be declared before non-array variables? Any input on this would be appreciated.

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• Finding a 3rd party QWidget with injected code & QWidget::find(hwnd)

  - by David Menard

  Hey, I have a Qt Dll wich I inject into a third-party Application using windows detours library: if(!DetourCreateProcessWithDll( Path, NULL, NULL, NULL, TRUE, CREATE_DEFAULT_ERROR_MODE | CREATE_SUSPENDED, NULL, NULL, &si, &pi, "C:\\Program Files\\Microsoft Research\\Detours Express 2.1\\bin\\detoured.dll", "C:\\Users\\Dave\\Documents\\Visual Studio 2008\\Projects\\XOR\\Debug\\XOR.dll", NULL)) and then I set a system-wide hook to intercept window creation: HHOOK h_hook = ::SetWindowsHookEx(WH_CBT, (HOOKPROC)CBTProc, Status::getInstance()->getXORInstance(), 0); Where XOR is my programs name, and Status::getInstance() is a Singleton where I keep globals. In my CBTProc callback, I want to intercept all windows that are QWidgets: HWND hwnd= FindWindow(L"QWidget", NULL); which works well, since I get a corresponding HWND (I checked with Spy++) Then, I want to get a pointer to the QWidget, so I can use its functions: QWidget* q = QWidget::find(hwnd); but here's the problem, the returned pointer is always 0. Am I not injecting my code into the process properly? Or am I not using QWidget::find() as I should? Thanks, Dave EDIT:If i change the QWidget::find() function to an exported function of my DLL, after setting the hooks (so I can set and catch a breakpoint), QWidgetPrivate::mapper is NULL.

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• Printing an invisible NSView

  - by Rodger Wilson

  Initially I created a simple program with a custom NSView. I drew a picture (certificate) and printed it! beautiful! Everything worked great! I them moved my custom NSView to an existing application. My hope was that when a user hit print it would print this certificate. Simple enough. I figured a could have a NSView pointer in my controller code. Then at initialization I would populate the pointer. Then when someone wanted to print the certificate it would print. The problem is that all of my drawing code is in the "drawRect" method. This method doesn't get called because this view is never displayed in a window. I have heart that others use non-visible NSView objects just for printing. What do I need to do. I really don't want to show this view to the screen. Rodger

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• Creating an AST node in Erlang

  - by dagda1

  Hi, I am playing about with Erlang and I am trying to write a simple arithmetic parser. I want to try and parse the following expression: ((12+3)-4) I want to parse the expression into a stack of AST nodes. When parsing this expression, I would first of all create a binary expression for the (12+3) expression which would look something like this in C#: var binaryStructure = new BinaryStructure(); binaryStructure.Left = IntegerLiteralExpression(12); binaryStructure.Right = IntegerLiteralExpression(4); binaryStructure.Operator = binaryExpression.Operator != BinaryOperatorType.Addition; I am quite new to Erlang and I am wondering how I would go about creating a structure like this in Erlang that I can place on a List that I would use as the stack of expressions. Can anyone suggest how to create such a tree like structure? Would a function be a good fit? Thanks Paul

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• Convert Double to String without precision loss in javascript

  - by holger

  I would like to convert a floating point variable to a string without losing any precision. I.e. I would like the string to have the same information as my floating point variable contains, since I use the output for further processing (even if it means that the string will be very long and readable). To put this more clearly, I would like to have functions for cyclic conversion var dA = 323423.23423423e4; var sA = toString(dA); var dnA = toDouble(sA); and I would like dnA and dA to be equal Thanks PS: Sources on the internet usually talk about how to round strings but I have not found information on exact representation. Also I am not interested in Arbitrary Precision calculations, I just need double precision floating point arithmetic.

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• A queue in C using structs and dynamic memory allocation (linked list)

  - by Martin Pugh

  I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc and C in general, so there could be something painfully obvious I've overlooked. Here is the code I am using: #include <stdio.h> #include <stdlib.h> struct node{ int data; //contains the actual data struct node *prev; //pointer to previous node (Closer to front) struct node *next; //pointer to next node (Closer to back) }; typedef struct node *Nodepointer; struct queue{ Nodepointer front; Nodepointer back; }; typedef struct queue *Queuepointer; main(){ Queuepointer myqueue; //create a queue called myqueue init(myqueue); //initialise the queue Nodepointer new = (Nodepointer)malloc(sizeof(struct node)); myqueue->front = new; } int init(Queuepointer q){ q = (Queuepointer)malloc(sizeof(struct queue)); q->front = NULL; q->back = NULL; } The idea is that the queue struct 'contains' the first and last nodes in a queue, and when a node is created, myqueue is updated. However, I cannot even get to that part (pop and push are written but omitted for brevity). The code is segfaulting at the line myqueue->front = new; with the following gdb output: Program received signal SIGSEGV, Segmentation fault. 0x08048401 in main () at queue.c:27 27 myqueue->front = new; Any idea what I'm doing wrong?

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• Expression Tree

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally in LINQ to SQL query the compiler translates it into parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

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• array of structs in C

  - by Hristo

  I'm trying to create an array of structs and also a pointer to that array. I don't know how large the array is going to be, so it should be dynamic. My struct would look something like this: typedef struct _stats_t { int hours[24]; int numPostsInHour; int days[7]; int numPostsInDay; int weeks[20]; int numPostsInWeek; int totNumLinesInPosts; int numPostsAnalyzed; } stats_t; ... and I need to have multiple of these structs for each file (unknown amount) that I will analyze. I'm not sure how to do this. I don't like the following approach because of the limit of the size of the array: # define MAX 10 typedef struct _stats_t { int hours[24]; int numPostsInHour; int days[7]; int numPostsInDay; int weeks[20]; int numPostsInWeek; int totNumLinesInPosts; int numPostsAnalyzed; } stats_t[MAX]; So how would I create this array? Also, would a pointer to this array would look something this? stats_t stats[]; stats_t *statsPtr = &stats[0]; Thanks, Hristo

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• sed/awk or other: increment a number by 1 keeping spacing characters

  - by WizardOfOdds

  I've got a string: (notice the spacing) eh oh 37 and I want it to become: eh oh 36 (so I want to keep the spacing) Using awk I don't find how to do it, so far I have: echo "eh oh 37" | awk '$3>=0&&$3<=99 {$3--} {print}' But this gives: eh oh 36 (the spacing characters where lost, because the field separator is ' ') Is there a way to ask awk something like "print the output using the exact same field separators as the input had"? Then I tried with sed, but got stuck after this: echo "eh oh 37" | sed -e 's/\([0-9][0-9]\)/.../' Can I do arithmetic from sed using a reference to the matching digits and have the output not modify the number of spacing characters? Note that it's related to my question concerning Emacs and how to apply this to some (big) Emacs region (using a replace region with Emacs's shell-command-on-region) but it's not an identical question: this one is specifically about how to "keep spaces" when working with awk/sed/etc.

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