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Why Android for enterprise applications?

- by mcabral

Recently one of our clients is considering the posibility of picking up an old WinMobile 5.0 project. Several features are to be added to the point it will be a major version update. The client is worried about the mobile market, and thinks there's a chance all the effort put in this development will have to be thrown away in a couple of year due to the dinamics of the mobile market and the deprecation of mobile devices. So, the client is not sure whether he should continue with Windows Mobile (changing from WM 5.0 to 6.X) or starting from scratch with another technology. From our part we have been studing the mobile market, looking for clues for which will be the winning horse. The safe move seems to continue with WM just because re writing an entire application from scratch involves more risks and delays. On the other hand WM seems to be losing market and the ghost of an exit on their part is growing stronger everyday. But what can be say about Android? Everyone is talking about it and is growing at full speed but what avantagies will it bring to the table? Why should we start a fresh applicaction on this technology? So the question remains the same.. is Andriod mature enough for an enterprise application? Will you recomend it to one of your clients? Will you port/rewrite a WM application to Andriod? What's the trade-off? EDIT: Addressing commentaries. The app is entirely built with C# and Compact Framework. The app is for logistics/management.

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Can anyone give me tips how to solve this using Graphs in C or Java?

- by peiska

Can anyone give me tips how to solve this using Graphs in C or Java? I have a rectangular sector, that I have to escape, and I have energy that goes disappear every step that i give in the area. I have to give the only one possible solution, the one that uses the least number of steps. If there are at least two sectors with the same number of steps (X1, Y1) and (X2, Y2) then choose the first if X1 < X2 or if X1 = X2 and Y1 < Y2. the position( 1,1) corresponds to the upper left corner. Examples: This is one sector,and i start with 40 of energy and in the position (3,3) 12 11 12 11 3 12 12 12 11 11 12 2 1 13 11 11 12 2 13 2 14 10 11 13 3 2 1 12 10 11 13 13 11 12 13 12 12 11 13 11 13 12 13 12 12 11 11 11 11 13 13 10 10 13 11 12 the best solution to exit the sector is the position (5, 1) the remain energy is 12 and i need 8 steeps to leave the area. for this sector i start with 8 of energy and in the position (3,4). 4 3 3 2 2 3 2 2 5 2 2 2 3 3 2 1 2 2 3 2 2 4 3 3 2 2 4 1 3 1 4 3 2 3 1 2 2 3 3 0 3 4 And for this one there is no way out, cause it looses all the energy.

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php XML DOM translates special chars to &#xYY;

- by ZiTAL

I send this with AJAX POST: <li><ul class "zone zCentral ui-sortable"><li><ul class="region rCol3 ui-sortable"><li class="" style=""><div><span class="tc tc_video">574081</span> <span>video: 'Mundo.Hoy': ¿Dónde habré olvidado... mi memoria?</span></div></li></ul></li></ul></li> I do this to create XML: header('Content-type: text/html; charset=utf-8'); if(isset($_POST) && isset($_POST['data'])) { $data = '<ul id="zone_container" class="ui-sortable">'; $data .= $_POST['data']; $data .= '</ul>'; $dom = new DOMDocument('1.0', 'utf-8'); $dom->loadXML($data); echo $dom->saveXML(); exit(); } and i get this: <?xml version="1.0"?> <ul id="zone_container" class="ui-sortable"> <li><ul class="zone zCentral ui-sortable"><li><ul class="region rCol3 ui-sortable"><li class="" style=""><div><span class="tc tc_video">574081</span> <span>video: 'Mundo.Hoy': ¿Dónde habré olvidado... mi memoria?</span></div> </li></ul></li></ul></li></ul> ¿Dónde habré olvidado... mi memoria? translates to: ¿Dónde habr&#xE9 ; olvidado... mi memoria? Y need original chars in the XML, these are utf-8 valid i don't know the reason for this encode :(

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32/64 bit problems with Eclipse CDT on Ubuntu

- by waffleShirt

I have just recently started running Linux on my PC and I am trying to start learning OpenGL. I am using the latest version of Eclipse CDT as my IDE, and my system is Ubuntu 10.10, 64 bit version. The problem I am having is that whenever I try to run a build from within the IDE I get the error message "Launch Failed. Binary Not Found." Ive done a lot of looking around on the internet but I still cant solve the problem. I know for a fact that the binary is built, it can be run from a terminal window. According to posts I have seen the problem is that Eclipse tries to run a 32 bit binary, but GCC 4.4.5 defaults to 64 bit binaries on a 64 bit system. Ive seen a lot of information about using the -m32 flag in makefiles, but then I still get the following output in Eclipse: make all g++ -o HelloWorld2 main.o /usr/bin/ld: i386 architecture of input file `main.o' is incompatible with i386:x86-64 output /usr/bin/ld: final link failed: Invalid operation collect2: ld returned 1 exit status make: *** [HelloWorld2] Error 1 What I would like to know is how to either get Eclipse to launch the 64 bit binaries, or have Eclipse correctly compile 32 bit binaries.

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program won't find math.h anymore

- by 130490868091234

After a long time, I downloaded a program I co-developed and tried to recompile it on my Ubuntu Linux 12.04, but it seems it does not find math.h anymore. This may be because something has changed recently in gcc, but I can't figure out if it's something wrong in src/Makefile.am or a missing dependency: Download from http://www.ub.edu/softevol/variscan/: tar xzf variscan-2.0.2.tar.gz cd variscan-2.0.2/ make distclean sh ./autogen.sh make I get: [...] gcc -DNDEBUG -O3 -W -Wall -ansi -pedantic -lm -o variscan variscan.o statistics.o common.o linefile.o memalloc.o dlist.o errabort.o dystring.o intExp.o kxTok.o pop.o window.o free.o output.o readphylip.o readaxt.o readmga.o readmaf.o readhapmap.o readxmfa.o readmav.o ran1.o swcolumn.o swnet.o swpoly.o swref.o statistics.o: In function `calculate_Fu_and_Li_D': statistics.c:(.text+0x497): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F': statistics.c:(.text+0x569): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_D_star': statistics.c:(.text+0x63b): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F_star': statistics.c:(.text+0x75c): undefined reference to `sqrt' statistics.o: In function `calculate_Tajima_D': statistics.c:(.text+0x85d): undefined reference to `sqrt' statistics.o:statistics.c:(.text+0xcb1): more undefined references to `sqrt' follow statistics.o: In function `calcRunMode21Stats': statistics.c:(.text+0xe02): undefined reference to `log' statistics.o: In function `correctedDivergence': statistics.c:(.text+0xe5a): undefined reference to `log' statistics.o: In function `calcRunMode22Stats': statistics.c:(.text+0x104a): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_fs': statistics.c:(.text+0x11a8): undefined reference to `fabsl' statistics.c:(.text+0x11ca): undefined reference to `powl' statistics.c:(.text+0x11f2): undefined reference to `logl' statistics.o: In function `calculateStatistics': statistics.c:(.text+0x13f2): undefined reference to `log' collect2: ld returned 1 exit status make[1]: *** [variscan] Error 1 make[1]: Leaving directory `/home/avilella/variscan/latest/variscan-2.0.2/src' make: *** [all-recursive] Error 1 The libraries are there because this simple example works perfectly well: $ gcc test.c -o test -lm $ cat test.c #include <stdio.h> #include <math.h> int main(void) { double x = 0.5; double result = sqrt(x); printf("The hyperbolic cosine of %lf is %lf\n", x, result); return 0; } Any ideas?

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Java try finally variations

- by Petr Gladkikh

This question nags me for a while but I did not found complete answer to it yet (e.g. this one is for C# http://stackoverflow.com/questions/463029/initializing-disposable-resources-outside-or-inside-try-finally). Consider two following Java code fragments: Closeable in = new FileInputStream("data.txt"); try { doSomething(in); } finally { in.close(); } and second variation Closeable in = null; try { in = new FileInputStream("data.txt"); doSomething(in); } finally { if (null != in) in.close(); } The part that worries me is that the thread might be somewhat interrupted between the moment resource is acquired (e.g. file is opened) but resulting value is not assigned to respective local variable. Is there any other scenarios the thread might be interrupted in the point above other than: InterruptedException (e.g. via Thread#interrupt()) or OutOfMemoryError exception is thrown JVM exits (e.g. via kill, System.exit()) Hardware fail (or bug in JVM for complete list :) I have read that second approach is somewhat more "idiomatic" but IMO in the scenario above there's no difference and in all other scenarios they are equal. So the question: What are the differences between the two? Which should I prefer if I do concerned about freeing resources (especially in heavily multi-threading applications)? Why? I would appreciate if anyone points me to parts of Java/JVM specs that support the answers.

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Releasing Excel after using Interop

- by figus

Hi everyone I've read many post looking for my answer, but all are similar to this: http://stackoverflow.com/questions/1610743/reading-excel-files-in-vb-net-leaves-excel-process-hanging My problem is that I don't quit the app... The idea is this: If a User has Excel Open, if he has the file I'm interested in open... get that Excel instance and do whatever I want to do... But I don't to close his File after I'm done... I want him to keep working on it, the problem is that when he closes Excel... The process keeps running... and running... and running after the user closes Excel with the X button... this is how I try to do it This piece is used to know if he has Excel open, and in the For I check for the file name I'm interested in. Try oApp = GetObject(, "Excel.Application") libroAbierto = True For Each libro As Microsoft.Office.Interop.Excel.Workbook In oApp.Workbooks If libro.Name = EquipoASeccionIdSeccion.Text & ".xlsm" Then Exit Try End If Next libroAbierto = False Catch ex As Exception oApp = New Microsoft.Office.Interop.Excel.Application End Try here would be my code... if he hasn't Excel open, I create a new instance, open the file and everything else. My code ends with this: If Not libroAbierto Then libroSeccion.Close(SaveChanges:=True) oApp.Quit() Else oApp.UserControl = True libroSeccion.Save() End If System.Runtime.InteropServices.Marshal.FinalReleaseComObject(libroOriginal) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(libroSeccion) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(origen) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(copiada) System.Runtime.InteropServices.Marshal.FinalReleaseComObject(oApp) libroOriginal = Nothing libroSeccion = Nothing oApp = Nothing origen = Nothing copiada = Nothing nuevosGuardados = True So you can see that, if I opened the file, I call oApp.Quit() and everything else and the Excel Process ends after a few seconds (maybe 5 aprox.) BUT if I mean the user to keep the file open (not calling Quit()), Excel process keeps running after the user closes Excel with the X button. Is there any way to do what I try to do?? Control a open instance of excel and releasing everything so when the user closes it with the X button, the Excel Process dies normally??? Thanks!!!

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Really strange problem with jailbroken iPhone 4. Lags but fixes by running Cydia a second

- by Charkel

I have jailbreaked my iPhone 4 iOS 4.1 with both limera1n and greenpois0n and the outcome is the same. My phone is really slow opening apps. (including Phone.app an SMS.app) they take about 10-15seconds to load. BUT if I start Cydia for only one second everything goes back to normal. (Please note that I have to have 3G or WI-FI access to do this) Until I let my phone sit for about 15 minutes then it's the same again. Please note that if I don't exit the apps they seem to continue working but with a bit of lag. Cydia also seems to be the only app not affected by the delay. "Loding Data" appears as quick as normal. These issues did not start to appear until about 2 weeks after I jailbreaked my phone. I have tried running "speed test" while it's in its slow state. I start the app and the app loads for like 15 seconds and then the result shows everyhting is good. All green. Since Cydia seems for fix it temporarily i figured it's jailbreak-related and not hardware-related.

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swfupload session problem destroy session

- by saquib

Hello Friends, I have a problem with swfupload. I am passing session_id() like this /upload-file.php?s=189477fcfa1ec7f630e70a09e1e84cae but its not maintaining session and destroying my current session (logging me out) here is code in file upload. <?php if(isset($_GET['s'])) { session_id($_GET['s']); session_start(); require_once 'admin/class/user.php'; $u = new User(); //Check for user logged in if($u->islogged() == FALSE) { header("location: index.php"); exit(); code continue ..... } because am not logged in server redirect me to the index.php this is swfupload debugger window output SWF DEBUG: ----- END SWF DEBUG OUTPUT ---- SWF DEBUG: SWF DEBUG: Event: fileDialogStart : Browsing files. Multi Select. Allowed file types: *.jpg SWF DEBUG: Select Handler: Received the files selected from the dialog. Processing the file list... SWF DEBUG: Event: fileQueued : File ID: SWFUpload_0_0 SWF DEBUG: Event: fileDialogComplete : Finished processing selected files. Files selected: 1. Files Queued: 1 SWF DEBUG: StartUpload: First file in queue SWF DEBUG: Event: uploadStart : File ID: SWFUpload_0_0 SWF DEBUG: ReturnUploadStart(): File accepted by startUpload event and readied for upload. Starting upload to /upload-file.php?s='189477fcfa1ec7f630e70a09e1e84cae' for File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress (OPEN): File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress: File ID: SWFUpload_0_0. Bytes: 317793. Total: 317793 SWF DEBUG: Event: uploadError: HTTP ERROR : File ID: SWFUpload_0_0. HTTP Status: 302. SWF DEBUG: Event: uploadComplete : Upload cycle complete. SWF DEBUG: StartUpload: First file in queue SWF DEBUG: StartUpload(): No files found in the queue.

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Installing Rails on Mountain Lion

- by Jordan Medlock

I was wondering if you could help me find why I cannot install Ruby on Rails on my MBP with OS X Mountain Lion. It's a weird problem and I'll give you as much info as I can. I've installed ruby and it's working at version 1.9.3 And I've installed ruby gems and it's worked for every other gem I've tried to install. It's version is 1.8.24 When I run $ sudo gem install rails it replies with the message: Successfully installed rails-3.2.8 1 gem installed Although when I ask it rails -v it returns: `Rails is not currently installed on this system. To get the latest version, simply type: $ sudo gem install rails You can then rerun your "rails" command.` What should I do? The rails bash file (/usr/bin/rails) contains: #!/usr/bin/ruby # Stub rails command to load rails from Gems or print an error if not installed. require 'rubygems' version = ">= 0" if ARGV.first =~ /^_(.*)_$/ and Gem::Version.correct? $1 then version = $1 ARGV.shift end begin gem 'railties', version or raise rescue Exception puts 'Rails is not currently installed on this system. To get the latest version, simply type:' puts puts ' $ sudo gem install rails' puts puts 'You can then rerun your "rails" command.' exit 0 end load Gem.bin_path('railties', 'rails', version) That must mean that the gem files aren't there or are old or corrupted How can I check that?

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run time error wats the wrong?

- by javacode

I am getting run time error import javax.mail.*; import javax.mail.internet.*; import java.util.*; public class SendMail { public static void main(String [] args)throws MessagingException { SendMail sm=new SendMail(); sm.postMail(new String[]{"[email protected]"},"hi","hello","[email protected]"); } public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException { boolean debug = false; //Set the host smtp address Properties props = new Properties(); props.put("mail.smtp.host", "webmail.emailmyname.com"); // create some properties and get the default Session Session session = Session.getDefaultInstance(props, null); session.setDebug(debug); // create a message Message msg = new MimeMessage(session); // set the from and to address InternetAddress addressFrom = new InternetAddress(from); msg.setFrom(addressFrom); InternetAddress[] addressTo = new InternetAddress[recipients.length]; for (int i = 0; i < recipients.length; i++) { addressTo[i] = new InternetAddress(recipients[i]); } msg.setRecipients(Message.RecipientType.TO, addressTo); // Optional : You can also set your custom headers in the Email if you Want msg.addHeader("MyHeaderName", "myHeaderValue"); // Setting the Subject and Content Type msg.setSubject(subject); msg.setContent(message, "text/plain"); Transport.send(msg); } } Error Exception in thread "main" java.lang.NoClassDefFoundError: SendMail Caused by: java.lang.ClassNotFoundException: SendMail at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) Could not find the main class: SendMail. Program will exit.

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Linker error: wants C++ virtual base class destructor

- by jdmuys

Hi, I have a link error where the linker complains that my concrete class's destructor is calling its abstract superclass destructor, the code of which is missing. This is using GCC 4.2 on Mac OS X from XCode. I saw http://stackoverflow.com/questions/307352/g-undefined-reference-to-typeinfo but it's not quite the same thing. Here is the linker error message: Undefined symbols: "ConnectionPool::~ConnectionPool()", referenced from: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool()in RKConnector.o ld: symbol(s) not found collect2: ld returned 1 exit status Here is the abstract base class declaration: class ConnectionPool { public: static ConnectionPool* newPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~ConnectionPool() =0; virtual int keepAlive() =0; virtual int disconnect() =0; virtual sql::Connection * getConnection(char *compression_scheme = NULL) =0; virtual void releaseConnection(sql::Connection * theConnection) =0; }; Here is the concrete class declaration: class AlwaysConnectedConnectionZPool: public ConnectionPool { protected: <snip data members> public: AlwaysConnectedConnectionZPool(std::string h, short p, std::string u, std::string pw, std::string b); virtual ~AlwaysConnectedConnectionZPool(); virtual int keepAlive(); // will make sure the connection doesn't time out. Call regularly virtual int disconnect(); // disconnects/destroys all connections. virtual sql::Connection * getConnection(char *compression_scheme = NULL); virtual void releaseConnection(sql::Connection * theConnection); }; Needless to say, all those members are implemented. Here is the destructor: AlwaysConnectedConnectionZPool::~AlwaysConnectedConnectionZPool() { printf("AlwaysConnectedConnectionZPool destructor call"); // nothing to destruct in fact } and also maybe the factory routine: ConnectionPool* ConnectionPool::newPool(std::string h, short p, std::string u, std::string pw, std::string b) { return new AlwaysConnectedConnectionZPool(h, p, u, pw, b); } I can fix this by artificially making my abstract base class concrete. But I'd rather do something better. Any idea? Thanks

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NSOpenGLFullScreen and SetSystemUIMode freeze bug!?

- by Mattias

Hi! I have a really strange problem which is perfectly re-producable using sample code! If I use Apple's NSOpenGLFullScreen sample I can click a button to enter fullscreen OpenGL mode. However if I click the mouse in the area where the menubar would be if I was running windowed mode, the entire program freezes because I really activate the menu-choice behind the OpenGL screen, so to speak. The solution I have found after some Googling is to use SetSystemUIMode to hide the menubar. Also I want to initiate the application to fullscreen at startup by adding a call to EnterFullScreen after initialization. Entering FullScreen works perfectly, BUT - if I add the call to SetSystemUIMode I get a really strange error! The entire screen hangs, the animation stops and no mouse coordinates seem to be reported. If I then exit the Fullscreen mode and press the FullScreen button again everything works and the menubar is gone.. What could be wrong here? I mean it obviously works to remove the menubar in that manner and it obviously works to enter fullscreen mode like that (using Cocoa), but why doesn't the combination work!? Pleeease help :) Sincerely, / Mattias

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Scheduling Jobs On web server

- by sirasad

Hi Folks We Want to Create an online game like this.I think that ,this type of games have a scheduling software on web server. For Example : Player Click to create a resource And resource creation will be take a moment like 20 Minutes.(Every resource creation time will be different). This message will send to web server application but this message will not processed at same time for example must be processed after 20 Minutes. The web server application after getting the message must be put the order in the Queue. We have Some big problems : 1- The Jobs must be complete by the web server application Even the player Exit the Game. I think that we must create something like Windows service on Web Server. Can we do it? or Is there a better way? 2- The Second problem depended on problem 1 .Because we will have many Jobs (every player can create 20,30 Jobs in every Loggin and we will have thousands of users) , So Our Scheduling System Must be Work On time . it's possible that , there is 100 , 1000 jobs in a same second , if application Can't Done Jobs in him Second will be use the next second Time and the next second jobs will shift to next second and etc. How We can do for this problem ? Cheers Asad Safari Agile Coach , Scrum Master

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Netbeans PHP Validation sees endif as a syntax error

- by Asaf

I have this part of code <?php for ($j=0; $j < $count; $j++): ?> <?php if(isset(votes[$j])): ?> <dt>something something</dt> <dd> <span><?php echo $result; ?>%</span> <div class="bar"> </div> </dd> <?php else: ?> <dt>info</dt> <dd> <span>0</span> <div class="bar"> <div style="width: 0px"></div> </div> </dd> <?php endif; ?> <?php endfor; ?> now Netbeans insists that on the endif line (near the end) there's a syntax error: Error Syntax error: expected: exit, identifier, variable, function... Is there some sort of known problem with the validation of endif on Netbeans ?

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How to write Java-like enums in C++ ?

- by Rahul G

Coming from Java background, I find C++'s enums very lame. I wanted to know how to write Java-like enums (the ones in which the enum values are objects, and can have attributes and methods) in C++. As an example, translate the following Java code (a part of it, sufficient to demonstrate the technique) to C++ : public enum Planet { MERCURY (3.303e+23, 2.4397e6), VENUS (4.869e+24, 6.0518e6), EARTH (5.976e+24, 6.37814e6), MARS (6.421e+23, 3.3972e6), JUPITER (1.9e+27, 7.1492e7), SATURN (5.688e+26, 6.0268e7), URANUS (8.686e+25, 2.5559e7), NEPTUNE (1.024e+26, 2.4746e7); private final double mass; // in kilograms private final double radius; // in meters Planet(double mass, double radius) { this.mass = mass; this.radius = radius; } private double mass() { return mass; } private double radius() { return radius; } // universal gravitational constant (m3 kg-1 s-2) public static final double G = 6.67300E-11; double surfaceGravity() { return G * mass / (radius * radius); } double surfaceWeight(double otherMass) { return otherMass * surfaceGravity(); } public static void main(String[] args) { if (args.length != 1) { System.err.println("Usage: java Planet <earth_weight>"); System.exit(-1); } double earthWeight = Double.parseDouble(args[0]); double mass = earthWeight/EARTH.surfaceGravity(); for (Planet p : Planet.values()) System.out.printf("Your weight on %s is %f%n", p, p.surfaceWeight(mass)); } } Any hep would be greatly appreciated! Thanks!

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select failing with C program but not shell

- by Gary

So I have a parent and child process, and the parent can read output from the child and send to the input of the child. So far, everything has been working fine with shell scripts, testing commands which input and output data. I just tested with a simple C program and couldn't get it to work. Here's the C program: #include <stdio.h> int main( void ) { char stuff[80]; printf("Enter some stuff:\n"); scanf("%s", stuff); return 0; } The problem with with the C program is that my select fails to read from the child fd and hence the program cannot finish. Here's the bit that does the select.. //wait till child is ready fd_set set; struct timeval timeout; FD_ZERO( &set ); // initialize fd set FD_SET( PARENT_READ, &set ); // add child in to set timeout.tv_sec = 3; timeout.tv_usec = 0; int r = select(FD_SETSIZE, &set, NULL, NULL, &timeout); if( r < 1 ) { // we didn't get any input exit(1); } Does anyone have any idea why this would happen with the C program and not a shell one? Thanks!

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Avoiding a fork()/SIGCHLD race condition

- by larry

Please consider the following fork()/SIGCHLD pseudo-code. // main program excerpt for (;;) { if ( is_time_to_make_babies ) { pid = fork(); if (pid == -1) { /* fail */ } else if (pid == 0) { /* child stuff */ print "child started" exit } else { /* parent stuff */ print "parent forked new child ", pid children.add(pid); } } } // SIGCHLD handler sigchld_handler(signo) { while ( (pid = wait(status, WNOHANG)) > 0 ) { print "parent caught SIGCHLD from ", pid children.remove(pid); } } In the above example there's a race-condition. It's possible for "/* child stuff */" to finish before "/* parent stuff */" starts which can result in a child's pid being added to the list of children after it's exited, and never being removed. When the time comes for the app to close down, the parent will wait endlessly for the already-finished child to finish. One solution I can think of to counter this is to have two lists: started_children and finished_children. I'd add to started_children in the same place I'm adding to children now. But in the signal handler, instead of removing from children I'd add to finished_children. When the app closes down, the parent can simply wait until the difference between started_children and finished_children is zero. Another possible solution I can think of is using shared-memory, e.g. share the parent's list of children and let the children .add and .remove themselves? But I don't know too much about this. EDIT: Another possible solution, which was the first thing that came to mind, is to simply add a sleep(1) at the start of /* child stuff */ but that smells funny to me, which is why I left it out. I'm also not even sure it's a 100% fix. So, how would you correct this race-condition? And if there's a well-established recommended pattern for this, please let me know! Thanks.

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I get this error: "glibc detected"

- by AKGMA

Hi I just wrote a piece of CPP code and I compiled it using G++ in ubuntu. When I run my code everything is fine, the code runs well and gives output but doesn't exit and it gives this error: *** glibc detected *** ./a.out: free(): invalid next size (fast): 0x09f931f0 *** ======= Backtrace: ========= /lib/libc.so.6(+0x6c501)[0x3de501] /lib/libc.so.6(+0x6dd70)[0x3dfd70] /lib/libc.so.6(cfree+0x6d)[0x3e2e5d] /usr/lib/libstdc++.so.6(_ZdlPv+0x21)[0x6e2441] ./a.out[0x8049ce6] /lib/libc.so.6(+0x2f69e)[0x3a169e] /lib/libc.so.6(+0x2f70f)[0x3a170f] /lib/libc.so.6(__libc_start_main+0xef)[0x388cef] ./a.out[0x8048a61] ======= Memory map: ======== 00219000-0021a000 r-xp 00000000 00:00 0 [vdso] 00354000-00370000 r-xp 00000000 08:01 8781845 /lib/ld-2.12.1.so 00370000-00371000 r--p 0001b000 08:01 8781845 /lib/ld-2.12.1.so 00371000-00372000 rw-p 0001c000 08:01 8781845 /lib/ld-2.12.1.so 00372000-004c9000 r-xp 00000000 08:01 8781869 /lib/libc-2.12.1.so 004c9000-004ca000 ---p 00157000 08:01 8781869 /lib/libc-2.12.1.so 004ca000-004cc000 r--p 00157000 08:01 8781869 /lib/libc-2.12.1.so 004cc000-004cd000 rw-p 00159000 08:01 8781869 /lib/libc-2.12.1.so 004cd000-004d0000 rw-p 00000000 00:00 0 00638000-00717000 r-xp 00000000 08:01 3935829 /usr/lib/libstdc++.so.6.0.14 00717000-0071b000 r--p 000de000 08:01 3935829 /usr/lib/libstdc++.so.6.0.14 0071b000-0071c000 rw-p 000e2000 08:01 3935829 /usr/lib/libstdc++.so.6.0.14 0071c000-00723000 rw-p 00000000 00:00 0 00909000-0092d000 r-xp 00000000 08:01 8781918 /lib/libm-2.12.1.so 0092d000-0092e000 r--p 00023000 08:01 8781918 /lib/libm-2.12.1.so 0092e000-0092f000 rw-p 00024000 08:01 8781918 /lib/libm-2.12.1.so 00fdb000-00ff5000 r-xp 00000000 08:01 8781903 /lib/libgcc_s.so.1 00ff5000-00ff6000 r--p 00019000 08:01 8781903 /lib/libgcc_s.so.1 00ff6000-00ff7000 rw-p 0001a000 08:01 8781903 /lib/libgcc_s.so.1 08048000-0804b000 r-xp 00000000 08:01 8652645 /home/akg/Desktop/contest/a.out 0804b000-0804c000 r--p 00002000 08:01 8652645 /home/akg/Desktop/contest/a.out 0804c000-0804d000 rw-p 00003000 08:01 8652645 /home/akg/Desktop/contest/a.out 09f93000-09fb4000 rw-p 00000000 00:00 0 [heap] b7600000-b7621000 rw-p 00000000 00:00 0 b7621000-b7700000 ---p 00000000 00:00 0 b7765000-b7768000 rw-p 00000000 00:00 0 b7775000-b7779000 rw-p 00000000 00:00 0 bf9a7000-bf9c8000 rw-p 00000000 00:00 0 [stack] Aborted What does this mean? How can i get rid of it? I'm not using malloc or free , I'm just using vector!

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Error when linking C executable to OpenCV

- by Ghilas BELHADJ

I'm compiling OpenCV under Ubuntu 13.10 using cMake. i've already compiled c++ programs and they works well. now i'm trying to compile a C file using this cMakeLists.txt cmake_minimum_required (VERSION 2.8) project (hello) find_package (OpenCV REQUIRED) add_executable (hello src/test.c) target_link_libraries (hello ${OpenCV_LIBS}) here is the test.c file: #include <stdio.h> #include <stdlib.h> #include <opencv/highgui.h> int main (int argc, char* argv[]) { IplImage* img = NULL; const char* window_title = "Hello, OpenCV!"; if (argc < 2) { fprintf (stderr, "usage: %s IMAGE\n", argv[0]); return EXIT_FAILURE; } img = cvLoadImage(argv[1], CV_LOAD_IMAGE_UNCHANGED); if (img == NULL) { fprintf (stderr, "couldn't open image file: %s\n", argv[1]); return EXIT_FAILURE; } cvNamedWindow (window_title, CV_WINDOW_AUTOSIZE); cvShowImage (window_title, img); cvWaitKey(0); cvDestroyAllWindows(); cvReleaseImage(&img); return EXIT_SUCCESS; } it returns me this error whene running cmake . then make to the project: Linking C executable hello /usr/bin/ld: CMakeFiles/hello.dir/src/test.c.o: undefined reference to symbol «lrint@@GLIBC_2.1» /lib/i386-linux-gnu/libm.so.6: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status make[2]: *** [hello] Erreur 1 make[1]: *** [CMakeFiles/hello.dir/all] Erreur 2 make: *** [all] Erreur 2

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rabbitmq-erlang-client, using rebar friendly pkg, works on dev env fails on rebar release

- by lfurrea

I am successfully using the rebar-friendly package of rabbitmq-erlang-client for a simple Hello World rebarized and OTP "compliant" app and things work fine on the dev environment. I am able to fire up an erl console and do my application:start(helloworld). and connect to the broker, open up a channel and communicate to queues. However, then I proceed to do rebar generate and it builds up the release just fine, but when I try to fire up from the self contained release package then things suddenly explode. I know rebar releases are known to be an obscure art, but I would like to know what are my options as far as deployment for an app using the rabbitmq-erlang-client. Below you will find the output of the console on the crash: =INFO REPORT==== 18-Dec-2012::16:41:35 === application: session_record exited: {{{badmatch, {error, {'EXIT', {undef, [{amqp_connection_sup,start_link, [{amqp_params_network,<<"guest">>,<<"guest">>,<<"/">>, "127.0.0.1",5672,0,0,0,infinity,none, [#Fun<amqp_auth_mechanisms.plain.3>, #Fun<amqp_auth_mechanisms.amqplain.3>], [],[]}], []}, {supervisor2,do_start_child_i,3, [{file,"src/supervisor2.erl"},{line,391}]}, {supervisor2,handle_call,3, [{file,"src/supervisor2.erl"},{line,413}]}, {gen_server,handle_msg,5, [{file,"gen_server.erl"},{line,588}]}, {proc_lib,init_p_do_apply,3, [{file,"proc_lib.erl"},{line,227}]}]}}}}, [{amqp_connection,start,1, [{file,"src/amqp_connection.erl"},{line,164}]}, {hello_qp,start_link,0,[{file,"src/hello_qp.erl"},{line,10}]}, {session_record_sup,init,1, [{file,"src/session_record_sup.erl"},{line,55}]}, {supervisor_bridge,init,1, [{file,"supervisor_bridge.erl"},{line,79}]}, {gen_server,init_it,6,[{file,"gen_server.erl"},{line,304}]}, {proc_lib,init_p_do_apply,3, [{file,"proc_lib.erl"},{line,227}]}]}, {session_record_app,start,[normal,[]]}} type: permanent

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How can I obtain the local TCP port and IP Address of my client program?

- by Dr Dork

Hello! I'm prepping for a simple work project and am trying to familiarize myself with the basics of socket programming in a Unix dev environment. At this point, I have some basic server side code and client side code setup to communicate. Currently, my client code successfully connects to the server code and the server code sends it a test message, then both quit out. Perfect! That's exactly what I wanted to accomplish. Now I'm playing around with the functions used to obtain info about the two environments (server and client). I'd like to obtain the local IP address and dynamically assigned TCP port of the client. The function I've found to do this is getsockname()... //setup the socket if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("client: socket"); continue; } //Retrieve the locally-bound name of the specified socket and store it in the sockaddr structure sa_len = sizeof(sa); getsock_check = getsockname(sockfd,(struct sockaddr *)&sa,(socklen_t *)&sa_len) ; if (getsock_check== -1) { perror("getsockname"); exit(1); } printf("Local IP address is: %s\n", inet_ntoa(sa.sin_addr)); printf("Local port is: %d\n", (int) ntohs(sa.sin_port)); but the output is always zero... Local IP address is: 0.0.0.0 Local port is: 0 does anyone see anything I might be or am definitely doing wrong? Thanks so much in advance for all your help!

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UDP sockets in ad hoc network (Ubuntu 9.10)

- by Ekhiotz

Hi! I am using BSD sockets in Ubuntu 9.10 to send UDP packets in broadcast with the following code: sock_fd = socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP); //sock_fd=socket(AF_INET,SOCK_DGRAM,0); receiver_addr.sin_family = PF_INET; //does not send with broadcast in ad hoc receiver_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST); inet_aton("169.254.255.255",&receiver_addr.sin_addr); receiver_addr.sin_port = htons(port); int broadcast = 1; // this call is what allows broadcast packets to be sent: if (setsockopt(sock_fd, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof broadcast) == -1) { perror("setsockopt (SO_BROADCAST)"); exit(1); } ret=sendto(sock_fd, packet, size, 0,(struct sockaddr*)&receiver_addr,sizeof(receiver_addr)); Note that is not all the code, it is only to have an idea. The program sends all the data with INADDR_BROADCAST if I am connected to an infrastructure wireless network. However, if my laptop is connected to an ad-hoc network, it is able to receive all the data, but not to send it. I have solved the problem using the 169.254.255.255 broadcast address, but I would like to know what is going on. Thank you in advance!

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Qt/PyQt dialog with togglable fullscreen mode - problem on Windows

- by Guard

I have a dialog created in PyQt. It's purpose and functionality don't matter. The init is: class MyDialog(QWidget, ui_module.Ui_Dialog): def __init__(self, parent=None): super(MyDialog, self).__init__(parent) self.setupUi(self) self.installEventFilter(self) self.setWindowFlags(Qt.Dialog | Qt.WindowTitleHint) self.showMaximized() Then I have event filtering method: def eventFilter(self, obj, event): if event.type() == QEvent.KeyPress: key = event.key() if key == Qt.Key_F11: if self.isFullScreen(): self.setWindowFlags(self._flags) if self._state == 'm': self.showMaximized() else: self.showNormal() self.setGeometry(self._geometry) else: self._state = 'm' if self.isMaximized() else 'n' self._flags = self.windowFlags() self._geometry = self.geometry() self.setWindowFlags(Qt.Tool | Qt.FramelessWindowHint) self.showFullScreen() return True elif key == Qt.Key_Escape: self.close() return QWidget.eventFilter(self, obj, event) As can be seen, Esc is used for dialog hiding, and F11 is used for toggling full-screen. In addition, if the user changed the dialog mode from the initial maximized to normal and possibly moved the dialog, it's state and position are restored after exiting the full-screen. Finally, the dialog is created on the MainWindow action triggered: d = MyDialog(self) d.show() It works fine on Linux (Ubuntu Lucid), but quite strange on Windows 7: if I go to the full-screen from the maximized mode, I can't exit full-screen (on F11 dialog disappears and appears in full-screen mode again). If I change the dialog's mode to Normal (by double-clicking its title), then go to full-screen and then return back, the dialog is shown in the normal mode, in the correct position, but without the title line. Most probably the reason for both cases is the same - the setWindowFlags doesn't work. But why? Is it also possible that it is the bug in the recent PyQt version? On Ubuntu I have 4.6.x from apt, and on Windows - the latest installer from the riverbank site.

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c++ issues with cin.fail() in my program

- by Wallace

I want to use input y to do saving thing,and r to do resuming, but then i write it in the following codes,and then I input y or r,I just to be noticed ""Please enter two positve numbers" this line code "if(x==(int)('y'))"and next line is ignored.how could this happen int main(){ cout<<"It's player_"<<player+1<<"'s turn please input a row and col,to save and exit,input 0,resume game input"<<endl; while(true){ cin>>x; if(x==(int)('y')) {save();has_saved=true;break;} if(x==(int)('r')) {resume();has_resumed=true;break;} cin>>y; if(cin.fail()){ cout<<"Please enter two positve numbers"<<endl; cin.clear(); cin.sync();} else if (x>n||x<1||y<1||y>n) { cout<<"your must input a positive number less or equal than "<<n<<endl; continue;} else if(chessboard[x][y]!=' ') {cout<<"Wrong input please try again!"<<endl; continue;} else { chessboard[x][y]=player_symbol[player+1]; break; } } }

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