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  • Array Assignment

    - by Mahesh
    Let me explain with an example - #include <iostream> void foo( int a[2], int b[2] ) // I understand that, compiler doesn't bother about the // array index and converts them to int *a, int *b { a = b ; // At this point, how ever assignment operation is valid. } int main() { int a[] = { 1,2 }; int b[] = { 3,4 }; foo( a, b ); a = b; // Why is this invalid here. return 0; } Is it because, array decays to a pointer when passed to a function foo(..), assignment operation is possible. And in main, is it because they are of type int[] which invalidates the assignment operation. Doesn't a,b in both the cases mean the same ? Thanks. Edit 1: When I do it in a function foo, it's assigning the b's starting element location to a. So, thinking in terms of it, what made the language developers not do the same in main(). Want to know the reason.

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  • Iterating over a String to check for a number and printing out the String value if it doesn't have a number

    - by wheelerlc64
    I have set up my function for checking for a number in a String, and printing out that String if it has no numbers, and putting up an error message if it does. Here is my code: public class NumberFunction { public boolean containsNbr(String str) { boolean containsNbr = false; if(str != null && !str.isEmpty()) { for(char c : str.toCharArray()) { if(containsNbr = Character.isDigit(c)) { System.out.println("Can't contain numbers in the word."); break; } else { System.out.println(str); } } } return containsNbr; } } import com.imports.validationexample.function.NumberFunction; public class Main { public static void main(String[] args) { NumberFunction nf = new NumberFunction(); System.out.println(nf.containsNbr("bill4")); } } I am trying to get it to print out the result to the console, but the result keeps printing multiple times and prints the boolean value, which I do not want, something like this: bill4 bill4 bill4 bill4 Can't contain numbers in the word. true Why is this happening? I've tried casting but that hasn't worked out either. Any help would be much appreciated.

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  • C# / this. and List<T>

    - by user3533030
    I am having trouble understanding how to initialize a List of objects and use it with methods inside of a class. I understand the mechanics of the List, but not how to initialize it inside a method and use it later. For example, I want to have a class that creates the List when it is constructed. Then, I want to use a method of that class to add elements to the list. The elements in the list are objects defined by the SolidWorks API. So, to construct the List, I used... public class ExportPoints : Exporter { public List<SldWorks.SketchPoint> listOfSketchPoints; public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); } public void createListOfFreePoints() { try { [imagine more code here] this.listOfSketchPoints.Add(pointTest); } catch (Exception e) { Debug.Print(e.ToString()); return; } } This fails during execution as if the listOfSketchPoints was never initialized as a List. So, I tried a hack and this worked: public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); this.listOfSketchPoints = listOfSketchPoints; } This approach creates the behavior that I want. However, it seems that I lack some understanding as to why this is necessary. Shouldn't it be possible to "initialize" a List that is a property of your object with a constructor? Why would you need to create the list, then assign the pointer of that new List to your property?

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  • Scan file contents into an array of a structure.

    - by ZaZu
    Hello, I have a structure in my program that contains a particular array. I want to scan a random file with numbers and put the contents into that array. This is my code : ( NOTE : This is a sample from a bigger program, so I need the structure and arrays as declared ) The contents of the file are basically : 5 4 3 2 5 3 4 2 #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; FILE *fin; fin=fopen("randomfile.txt","r"); for(i=0;i<5;i++){ fscanf(fin,"%5.2f\t",(*test).what[z][x]); } fclose(fin); return 0; } But the problem is, whenever this I run this code, I get this error : (25) : warning 508 - Data of type 'double' supplied where a pointer is required I tried adding do{ for(i=0;i<5;i++){ q=fscanf(fin,"%5.2f\t",(*test).what[z][x]); } }while(q!=EOF); But that didnt work either, it gives the same error. Does anyone have a solution to this problem ?

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  • POSIX Sockets: How to detect Ctrl-C sent over Telnet?

    - by ogott
    Short Question What's the right way to handle a Ctrl-C event sent over Telnet on the server side? Long Question After calling recv() on a socket, I'd like to handle some situations appropriately. One of them is to return a certain error code when Ctrl-C was received. What's the correct way to detect this? The following works, but it just doesn't seem right: size_t recv_count; static char ctrl_c[5] = {0xff, 0xf4, 0xff, 0xfd, 0x06}; recv_count = recv(socket, buffer, buffer_size, 0); if (recv_count == sizeof(ctrl_c) && memcmp(buffer, ctrl_c, sizeof(ctrl_c) == 0) { return CTRL_C_RECEIVED; } I found a comment on Ctrl-C in a side-note in this UNIX Socket FAQ: [...] (by the way, out-of-band is often used for that ctrl-C, too). As I understand, receiving out-of-band data is done using recv() with a certain flag as the last parameter. But when I'm waiting for data using recv() as I do in the code above, I can't read out-of-band data at the same time. Apart from that, I'm getting something using recv() without that oob-flag.

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  • Class is not applying to submit button

    - by Mayur
    Hi All, I m Trying to apply a class to following submit button Code: <input type="submit" value="Submit" name="commit"> css : .confirm-button-submit { width : 79px; font : bold 12px sans-serif;; color : #000; background : url("../images/confirm-btn.png") 0 -33px no-repeat; text-decoration : none; margin-top :0px; text-align:center; border:0px; cursor : pointer; height:170px; } .confirm-button a { display : block; width : 79px; padding : 8px 0px 12px 0px; font : bold 12px sans-serif;; color : #000; background : url("../images/confirm-btn.png") 0 -33px no-repeat; text-decoration : none; margin-top :0px; text-align:center; } .confirm-button a:hover { display : block; width : 79px; padding : 8px 0px 12px 0px; font : bold 12px sans-serif;; color : #fff; background : url("../images/confirm-btn.png") 0 0 no-repeat; text-decoration : none; margin-top :0px; text-align:center; } But its not working proper what to do Thanks

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  • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

    - by devoured elysium
    When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid, not the key. Or am I wrong? If what we need is the shmid, what is the point in not just creating a random key every time? Edit @link text one can read: What about this key nonsense? How do we create one? Well, since the type key_t is actually just a long, you can use any number you want. But what if you hard-code the number and some other unrelated program hardcodes the same number but wants another queue? The solution is to use the ftok() function which generates a key from two arguments. Reading this, it gives me the impression that what one needs to attach to a shared-memory block is the key. But this isn't true, is it? Thanks

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  • Socket send recv functions

    - by viswanathan
    I have created a socket using the following lines of code. Now i change the value of the socket i get like this m_Socket++; Even now the send recv socket functions succeeds without throwing SOCKET_ERROR. I expect that it must throw error. Am i doing something wrong. struct sockaddr_in ServerSock; // Socket address structure to bind the Port Number to listen to char *localIP ; SOCKET SocServer; //To Set up the sockaddr structure ServerSock.sin_family = AF_INET; ServerSock.sin_addr.s_addr = INADDR_ANY; ServerSock.sin_port = htons(pLantronics->m_wRIPortNo); // To Create a socket for listening on wPortNumber if(( SocServer = socket( AF_INET, SOCK_STREAM, 0 )) == INVALID_SOCKET ) { return FALSE; } //To bind the socket with wPortNumber if(bind(SocServer,(sockaddr*)&ServerSock,sizeof(ServerSock))!=0) { return FALSE; } // To Listen for the connection on wPortNumber if(listen(SocServer,SOMAXCONN)!=0) { return FALSE; } // Structure to get the IP Address of the connecting Entity sockaddr_in insock; int insocklen=sizeof(insock); //To accept the Incoming connection on the wPortNumber pLantronics->m_Socket=accept(SocServer,(struct sockaddr*)&insock,&insocklen); if(pLantronics->m_Socket == INVALID_SOCKET) { shutdown(SocServer, 2 ); closesocket(SocServer ); return FALSE; } // To make socket non-blocking DWORD dwNonBlocking = 1; if(ioctlsocket( pLantronics->m_Socket, FIONBIO, &dwNonBlocking )) { shutdown(pLantronics->m_Socket, 2); closesocket(pLantronics->m_Socket); return FALSE; } pLantronics->m_sModemName = inet_ntoa(insock.sin_addr); Now i do m_Socket++;//change to some other number ideally expecting send recv to fail. Even now the send recv socket functions succeeds without throwing SOCKET_ERROR. I expect that it must throw error. Am i doing something wrong.

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  • Convert one delphi code line to c++

    - by user1332636
    How can I write that line in c++? This is the code in delphi type TSettings = record sFileName: String[50]; siInstallFolder: Byte; bRunFile: Boolean; ... end; .. var i: dword; sZdData: PChar; Settings :Tsettings; begin .... ZeroMemory(@Settings, sizeof(Tsettings)); settings := Tsettings(Pointer(@sZdData[i])^); // this code to c++ c++ code (hope the rest is OK) struct TSettings{ char sFileName[50]; byte siInstallFolder; bool bRunFile; ... } Settings; ... DWORD i; LPBYTE sZdData; ZeroMemory(&Settings, sizeof(TSettings)); Settings = ????? // im failing here i dunno what to do // i need same as in delphi code above

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  • CArray doesn't call copy constructors on memory reallocations, now what?

    - by MMx
    Suppose I have a class that requires copy constructor to be called to make a correct copy of: struct CWeird { CWeird() { number = 47; target = &number; } CWeird(const CWeird &other) : number(other.number), target(&number) { } void output() { printf("%d %d\n", *target, number); } int *target, number; }; Now the trouble is that CArray doesn't call copy constructors on its elements when reallocating memory (only memcpy from the old memory to the new), e.g. this code CArray<CWeird> a; a.SetSize(1); a[0].output(); a.SetSize(2); a[0].output(); results in 47 47 -572662307 47 I don't get this. Why is it that std::vector can copy the same objects properly and CArray can't? What's the lesson here? Should I use only classes that don't require explicit copy constructors? Or is it a bad idea to use CArray for anything serious?

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  • Search box with images strange issue in ie

    - by mebots
    Have the following searchbox image: With the following code and css: #searchcontainer { margin: 40px 0 0 0; } .search { float: right; margin: 0; padding: 0; height: 21px; width: 310px; } .search input, .search button { margin: 0; padding: 0; font-size: 0.9em; color: #A7A9AC; border: 0; outline: none; } .search input.box { margin: 0; padding: 2px 5px 0 5px; width:230px; height: 19px; background: #FFF url(images/search.gif) no-repeat top left; } .search input.btn { margin: 0 0 0 -5px; padding: 0; width:70px; height: 21px; cursor:pointer; cursor: hand; /* cross browser */ text-indent: -9999px; background: #FFF url(images/search.gif) no-repeat top right; } <div id="searchcontainer"> <form id="searchform" class="search" method="post" action="#"> <input name="box" type="text" value="zoek..." class="box" /> <input name="btn" type="button" class="btn" /> </form> </div> In firefox it looks ok, but in ie and chrome the button "Zoek" goes down a bit, see image In my opinion the css is ok. but can't find where it goes wrong.

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  • Can I make a derived class inherit a derived member from its base class in Java?

    - by Eric
    I have code that looks like this: public class A { public void doStuff() { System.out.print("Stuff successfully done"); } } public class B extends A { public void doStuff() { System.out.print("Stuff successfully done, but in a different way"); } public void doMoreStuff() { System.out.print("More advanced stuff successully done"); } } public class AWrapper { public A member; public AWrapper(A member) { this.member = member; } public void doStuffWithMember() { a.doStuff(); } } public class BWrapper extends AWrapper { public B member; public BWrapper(B member) { super(member); //Pointer to member stored in two places: this.member = member; //Not great if one changes, but the other does not } public void doStuffWithMember() { member.doMoreStuff(); } } However, there is a problem with this code. I'm storing a reference to the member in two places, but if one changes and the other does not, there could be trouble. I know that in Java, an inherited method can narrow down its return type (and perhaps arguments, but I'm not certain) to a derived class. Is the same true of fields?

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  • Java socket bug on linux (0xFF sent, -3 received)

    - by Marius
    While working on a WebSocket server in Java I came across this strange bug. I've reduced it down to two small java files, one is the server, the other is the client. The client simply sends 0x00, the string Hello and then 0xFF (per the WebSocket specification). On my windows machine, the server prints the following: Listening byte: 0 72 101 108 108 111 recieved: 'Hello' While on my unix box the same code prints the following: Listening byte: 0 72 101 108 108 111 -3 Instead of receiving 0xFF it gets -3, never breaks out of the loop and never prints what it has received. The important part of the code looks like this: byte b = (byte)in.read(); System.out.println("byte: "+b); StringBuilder input = new StringBuilder(); b = (byte)in.read(); while((b & 0xFF) != 0xFF){ input.append((char)b); System.out.print(b+" "); b = (byte)in.read(); } inputLine = input.toString(); System.out.println("recieved: '" + inputLine+"'"); if(inputLine.equals("bye")){ break; } I've also uploaded the two files to my server: Server.java Client.java My Windows machine is running windows 7 and my Linux machine is running Debian

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  • Game design flaw, need help investigating

    - by Snake
    I am not sure if I will be able to get help here but I would give it a shot. The problem is I dont know where the problem is. I have a cards game, in which when you "human" play by dragging a card, then at the end of card being dragged, a handler using postExecute is called with delay of 0.5 sec to start the next player in turn (which is a bot) The bot chooses the color and plays it and at the end of the animation (the card moving to the middle) a handler is started for the next bot and so on. Once the play reaches again to the human player, it waits for his touchs to drag the crad and start the cycle again. The problem that in production, sometimes I am getting errors. The error is resulting in somehow messing up the sequence which ends up with players having more cards than others. After investigation, I found that the transition from human to bot is the problem. Somehow, the transition is happening twice (meaning handler calling post execute twice and the bot is playing twice and everything is messed up). Its been mutliple months and I can't reproduce it (to fix it) and I cna't figure out why this is happeneing? ANY IDEA how I can go after it? How can I get more info about or how can I solve something like that? any pointer would help me

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  • Can you target Google Chrome? (Yes, you can)

    - by Kyle Sevenoaks
    Hi, I need to position this update button on www.euroworker.no/order (you'll have to add an item to the cart, use the Kjøp button to add and Handlevogn to view the cart). Works in FF and IE. (Although there is another alignment problems with IE) but not in Chrome or Safari. I had it working before, but the only thing I can think of to do is target safari and Chrome. Is this possible? Here's the CSS and HTML(Smarty) for you. HTML(Smarty): {capture assign="cartUpdate"} <div id="cartUpdate"><!--<input type="submit" class="submit" value="{tn _update}" />--> <button type="submit" class="submit" id="oppdatersubmit" name="saveFields" title="Oppdater" value="">&nbsp;</button> </div> {/capture} {assign var="cartUpdate" value=$cartUpdate|@str_split:10000} {php}$GLOBALS['cartUpdate'] = $this->get_template_vars('cartUpdate'); $this->assign_by_ref('GLOBALS', $GLOBALS);{/php} {form action="controller=order action=update" method="POST" enctype="multipart/form-data" handle=$form id="cartItems"} CONTENT {/form} And the CSS: #oppdatersubmit { background-image:url(../../upload/oppdater.png); background-repeat:no-repeat; background-position:left; background-color:none; border:none; overflow:hidden; outline:none; white-space: nowrap; width:77px; height:25px; cursor:pointer; position:absolute; } #cartUpdate { position:absolute; width:160px; height:30px; left:580px; bottom:130px; } Need to change these for Chrome and Safari. Thanks.

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  • How to delete Drawn Line in java?

    - by Jeyjey
    Hello Folks, well this is my code: import javax.swing.; import javax.; import java.awt.; import java.awt.Color; import java.awt.Graphics.; import java.awt.event.*; import javax.swing.UIManager; public class SimpleGUI extends JFrame{ public SimpleGUI(){ this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ; } public void go(){ Drawpanel = new Mypanel(); JFrame frame = new JFrame("Chasing Line"); frame.getContentPane().add(BorderLayout.CENTER, Drawpanel); frame.setSize(300,300); frame.setVisible(true); Drawpanel.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() { public void mouseMoved(java.awt.event.MouseEvent evt) { DrawpanelMouseMoved(evt); } }); } public void DrawpanelMouseMoved(java.awt.event.MouseEvent evt) { xpos=evt.getX(); ypos=evt.getY(); System.out.println("Coordinates : X :"+ xpos+"Y: "+ypos); Drawpanel.paintImage(xpos,ypos); } class Mypanel extends JPanel{ public void paintImage(int xpost,int ypost){ Graphics d = getGraphics(); d.setColor(Color.black); d.drawLine(xpost, 0, xpost, this.getHeight()); d.setColor(Color.red); d.drawLine(0, ypost, this.getWidth(),ypost); this.validate(); } } // end the inner class public static void main(String[] args){ try { UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); } catch(Exception e) { System.err.println("Look and feel not set"); } SimpleGUI win = new SimpleGUI(); win.go(); } Mypanel Drawpanel; private int xpos=0; private int ypos=0; } // close SimpleGUI class The problem is how can i delete the old lines?, i mea,make only the current x and y lines appear on the screen, make the intersection between both lines "follow" the mouse pointer. thanks for any reply.

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  • Refetching a previously visited page

    - by user613665
    All, I am having a field day with page refetching. Any help or pointer will be greatly appreciated!! The behavior is a bit specific to mobile browser. Problem: I have two pages and created a shortcut link to pg#1 in the home page. Through a form submit button, user is taken from pg#1 to pg#2. All that is working fine. Now once I am on pg#2. I will leave the browser and click the shortcut later. The browser will stay on pg#2 and won't go to pg#1 even though the path in URLS is different between the two views. It is almost like Django decides that since I have already visited view#1, it doesn't need to fetch it again. This problem or behavior doesn't happen if I move the same code that handle the two views and the templates to a bare bone test project. Setup: I am using django-registration, context session. I am not using any HTML caching tag. I already have DEBUG turned on in my settings.py. Are there other ways that I can tell what the server is doing. Thanks in advance. pdxMobile Update: Here is the code snippets. def sendmsg(request): if request.method =='POST': messages.add_message(request, messages.INFO, "Hello world") return redirect ('rcvmsg') return render_to_response('sendMsg.html',RequestContext(request)) def rcvmsg(request): '''view that receives the msg.''' printMsg ='Didnt get a message' if messages: thisMsg = messages.get_messages(request) for rcvMsg in thisMsg: printMsg = rcvMsg return render_to_response('rcvMsg.html',{'print_msg':printMsg},RequestContext(request)) URL: url(r'^rcvMsg/','mydomain.mainApp.views.rcvmsg',name='rcvmsg'), (r'^sendMsg/code','mydomain.mainApp.views.sendmsg'),

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  • php parsing csv with ftell

    - by Robert82
    I have a 500mb csv file with over 500,000 lines, each with 80 fields. I am using fget to process the file line by line. $col1 = array(); while (($row = fgetcsv($handle, 1000, ",")) !== FALSE) { $col1[] = $row[0]; } Because of an execution time limit on the PHP file by my hosting provider (120 seconds), I can't process the whole file in one run. I tried using ftell() and fseek() to remember the last position for restart. The trouble is, sometimes the ftell() position is in the middle of a row, and resuming means missing the first half of the row. Is there an elegant way to know the last line successfully processed, and resume from the one after it? I realize I can do a simple counter, and then loop through to that point again, but that would produce diminishing returns on the rows I can process towards the end of the file. Is there something like ftell() and fseek() that would work in my case? Or a way to limit ftell() to return the pointer for the end of the previous line?

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  • Is this an error in "More Effective C++" in Item28?

    - by particle128
    I encountered a question when I was reading the item28 in More Effective C++ .In this item, the author shows to us that we can use member template in SmartPtr such that the SmartPtr<Cassette> can be converted to SmartPtr<MusicProduct>. The following code is not the same as in the book,but has the same effect. #include <iostream> class Base{}; class Derived:public Base{}; template<typename T> class smart{ public: smart(T* ptr):ptr(ptr){} template<typename U> operator smart<U>() { return smart<U>(ptr); } ~smart(){delete ptr;} private: T* ptr; }; void test(const smart<Base>& ) {} int main() { smart<Derived> sd(new Derived); test(sd); return 0; } It indeed can be compiled without compilation error. But when I ran the executable file, I got a core dump. I think that's because the member function of the conversion operator makes a temporary smart, which has a pointer to the same ptr in sd (its type is smart<Derived>). So the delete directive operates twice. What's more, after calling test, we can never use sd any more, since ptr in sd has already been delete. Now my questions are : Is my thought right? Or my code is not the same as the original code in the book? If my thought is right, is there any method to do this? Thanks very much for your help.

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  • What is my error in a map in java?

    - by amveg
    Hello everyone I am trying to solve this problem: http://www.cstutoringcenter.com/problems/problems.php?id=4, but I cant figure out why my code doesnt solve this, I mean in the "for" how can I can multiply the letters? what is my error?, It just tell always 7, but I want to multiple all the letters, I hope you can help me enter code here public class ejercicio3 { public static void main(String args[]) { Map<Character, Integer> telefono = new HashMap<Character, Integer>(); telefono.put('A', 2); telefono.put('B', 2); telefono.put('C', 2); telefono.put('D', 3); telefono.put('E', 3); telefono.put('F', 3); telefono.put('G', 4); telefono.put('H', 4); telefono.put('I', 4); telefono.put('J', 5); telefono.put('K', 5); telefono.put('L', 5); telefono.put('M', 6); telefono.put('N', 6); telefono.put('O', 6); telefono.put('P', 7); telefono.put('R', 7); telefono.put('S', 7); telefono.put('T', 8); telefono.put('U', 8); telefono.put('V', 8); telefono.put('W', 9); telefono.put('X', 9); telefono.put('Y', 9); String mensaje = "Practice"; int producto = 1; for (char c : mensaje.toCharArray()) { if (telefono.containsKey(c)) { producto = telefono.get(c) * producto; System.out.println(producto); } } } }

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  • Maximum length of a std::basic_string<_CharT> string

    - by themoondothshine
    Hey all, I was wondering how one can fix an upper limit for the length of a string (in C++) for a given platform. I scrutinized a lot of libraries, and most of them define it arbitrarily. The GNU C++ STL (the one with experimental C++0x features) has quite a definition: size_t npos = size_t(-1); /*!< The maximum value that can be stored in a variable of type size_t */ size_t _S_max_len = ((npos - sizeof(_Rep_base))/sizeof(_CharT) - 1) / 4; /*!< Where _CharT is a template parameter; _Rep_base is a structure which encapsulates the allocated memory */ Here's how I understand the formula: The size_t type must hold the count of units allocated to the string (where each unit is of type _CharT) Theoretically, the maximum value that a variable of type size_t can take on is the total number of units of 1 byte (ie, of type char) that may be allocated The previous value minus the overhead required to keep track of the allocated memory (_Rep_base) is therefore the maximum number of units in a string. Divide this value by sizeof(_CharT) as _CharT may require more than a byte Subtract 1 from the previous value to account for a terminating character Finally, that leave the division by 4. I have absolutely no idea why! I looked at a lot of places for an explanation, but couldn't find a satisfactory one anywhere (that's why I've been trying to make up something for it! Please correct me if I'm wrong!!).

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  • Using memset on structures in C++

    - by garry
    Hey guys. I am working on fixing older code for my job. It is currently written in C++. They converted static allocation to dynamic but didn't edit the memsets/memcmp/memcpy. This is my first programming internship so bare with my newbe-like question. The following code is in C, but I want to have it in C++ ( I read that malloc isn't good practice in C++). I have two scenarios: First, we have f created. Then you use &f in order to fill with zero. The second is a pointer *pf. I'm not sure how to set pf to all 0's like the previous example in C++. Could you just do pf = new foo instead of malloc and then call memset(pf, 0, sizeof(foo))? struct foo { ... } f; memset( &f, 0, sizeof(f) ); //or struct foo { ... } *pf; pf = (struct foo*) malloc( sizeof(*pf) ); memset( pf, 0, sizeof(*pf) );

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  • Automatically Persisting a Complex Java Object

    - by VeeArr
    For a project I am working on, I need to persist a number of POJOs to a database. The POJOs class definitions are sometimes highly nested, but they should flatten okay, as the nesting is tree-like and contains no cycles (and the base elements are eventually primitives/Strings). It is preferred that the solution used create one table per data type and that the tables will have one field per primitive member in the POJO. Subclassing and similar problems are not issues for this particular project. Does anybody know of any existing solutions that can: Automatically generate a CREATE TABLE definition from the class definition Automatically generate a query to persist an object to the database, given an instance of the object Automatically generate a query to retrieve an object from the database and return it as a POJO, given a key. Solutions that can do this with minimum modifications/annotions to the class files and minimum external configuration are preferred. Example: Java classes //Class to be persisted class TypeA { String guid; long timestamp; TypeB data1; TypeC data2; } class TypeB { int id; int someData; } class TypeC { int id; int otherData; } Could map to CREATE TABLE TypeA ( guid CHAR(255), timestamp BIGINT, data1_id INT, data1_someData INT, data2_id INt, data2_otherData INT ); Or something similar.

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  • std::thread and class constructor and destructor

    - by toeplitz
    When testing threads in C++11 I have created the following example: #include <iostream> #include <thread> class Foo { public: Foo(void) { std::cout << "Constructor called: " << this << std::endl; } ~Foo(void) { std::cout << "Destructor called: " << this << std::endl; } void operator()() const { std::cout << "Operatior called: " << this << std::endl; } }; void test_normal(void) { std::cout << "====> Standard example:" << std::endl; Foo f; } void test_thread(void) { std::cout << "====> Thread example:" << std::endl; Foo f; std::thread t(f); t.detach(); } int main(int argc, char **argv) { test_normal(); test_thread(); for(;;); } Which prints the following: Why is the destructor called 6 times for the thread? And why does the thread report different memory locations?

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  • free( ) pointers

    - by user1043625
    I'm required to use a special library to keep track of my memory leaks where malloc()= allocate( ) and free( ) = unallocate( ). I'm trying to complete free a linked-list but it seems like the "root" value isn't being freed. typedef struct _node { struct _node *child; char *command; } Command_list; void delete_commands(Command_list **root) { Command_list *temp; while( *root != NULL ){ temp = (*root)->child; //printf("STRING: %s\n", *root->command ); unallocate( *root ); *root = temp; } } The function that's calling it void file_processing( .... ){ Command_list *root = allocate(sizeof (Command_list)); root = NULL; .... delete_commands( &root ); } } I believe that Command_list *root = allocate(sizeof (Command_list)) isn't being properly de-allocated for some reason. Anyone can give me some hints? UPDATE: I found out that instead of Command_list *root = allocate(sizeof (Command_list)); root = NULL; this works: Command_list *root = NULL;

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