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• All files gone after running fsck. How can I recover my files?

  - by cinlung

  I am a newbie in Linux. So this is my story I installed Ubuntu server 10.04lts. It worked great for many months, until today i decided to run fsck on the system partition and although it warned me, I kept pressing yes and now it will only boot into grub prompt. So i read some article and tried grub reinstall. But before performing grub reinstall, i decided to run fsck again from Ubuntu 10.04 lts for desktop live CD. The fsck painfully passes, now my drive is recognized as ext4 system and I am able to mount it again. However, all i can see is just boot directory and lost&found. I tried to perform grub reinstalling by doing grup-install stuff, now my grub is still not loading right, my files are missing, and the weird thing is that the amount I found used by boot and lost n found is only 5gb and the amount used in he hdd is 8 gb. So my files must be somewhere in the hdd. Is there any sinple way maybe a windows tool or something yo recover my files? I only need to retrieve my database backup and everything else can go. I am freaking out here. Please help.

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• How do I partition my Hard drive to install Kubuntu?

  - by Xdflames

  I am a complete newbie to partitioning and I would like some guidance here. Can anyone explain what exactly I should be doing here? I am installing Kubuntu 12.04 on a currently Windows 7 laptop. My current Partitions say this: /dev/sda /dev/sda1 ntfs 104 MB 35 MB /dev/sda2 ntfs 319965 MB 87164 MB Basically, what I want is some guidance on what exactly to do here. All I want is a partition for my OS (Which will be Kubuntu 12.04) and a partition for all of my data. I also want to restart fresh with my hard drive, with only what I mentioned on here. I am installing Kubuntu from a flash drive (I set it up as a bootable device with Universal-USB-Installer-1.9.0.9), as I do not have any blank CDs/DVDs to burn to. What should I name my partitions? What should I set the type as? What size do they need to be? Edit: My hard drive is 320GB. Just looked it up in my BIOS. This computer will mainly be used for internet browsing and overall just messing around with the Linux OS.

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• What and all the areas of a Linux a PHP developer should know about? (Like just commands of it or something advanced)

  - by droidsites

  I've developed a website using PHP but I implemented it on Windows OS and hosted it on Windows server. I just searched the PHP job market to know the on-going technology requirement and to keep my knowledge up-to-date accordingly with the job market. I see more are asking for LAMP stack. I understand the sort of skills required for a developer in PHP and MySQL. But coming to the Linux and Apache what kind of the skills exactly companies expect from a developer? On what should I be focusing in case of Linux, Apache whilst developing my website using these LAMP stack? I am going to develop a new website and want it to be using LAMP. But I want to know what difference it makes? Why LAMP stack got more demand in the job market compared to WAMP ? Edit: Sorry I thought my question is creating confusion ... so I put my question in different words as What and all the areas of a Linux a PHP developer should know about? (Like just commands of it or something advanced) Note: I am Linux newbie

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• How to troubleshoot GPU freezes?

  - by dlsmith2

  So in advance I'll just say I am a total linux newbie, so be kind. I just downloaded Ubuntu 11.10 and this is my first experience with Linux. I enjoy it so far and actually enjoy it except for when my computer freezes. This has been quite often so far. I've done a little research and it seems my problem is with the GPU. When it does freeze I can move the cursor but cannot click on anything. I also cannot run Alt+F2 xkill. So my only previous experience has been with Windows and I would normally solve an issue like this with Ctrl+Alt+Delete and just shut down the offending program. I do not know how to do this in Ubuntu and not even sure this would even work. Please help me if you can, how do I deal with a freeze without having to resort to a hard shutdown, I cannot seem to run the computer over one hour without experiencing this issue. I tried accessing my GRUB menu on startup but I can't even seem to do that. Also the only real program I have been running whenever this happens seems to be Firefox. Thank you, appreciate any help. After running lspci | grep VGA command prompt: 00:12.0 VGA compatible controller: nVidia Corporation C67 [GeForce 7150M / nForce 630M] (rev a2)*****

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• Why is my USB data transfer so slow?

  - by Dave M G

  Whenever I do any kind of file transfer using USB, whether to a USB stick, or with my Android phone, or anything else, it is ridiculously slow. It says 59.8 KB/sec, which would be an awesome speed if this were 1991 and I was using a modem to dial up to my local BBS. Surely USB technology is better than that...? 37 seconds to move less data than the equivelent of 1 MP3 file? Also, regardless of what it says about speed and time, the reality is much, much slower. I routinely see it say something like "37 seconds left" and have to wait for minutes. Sometimes, if I want to move large amounts of files, it can say it will take 8 hours or more. Is this normal? My computer may not be the most awesome on the market, and about a year old, but it's an i5 with 4GB RAM and modern components, so surely this isn't the hardware's fault. What can I do to get better USB data transfer performance? Also, I did look at this question, but my newbie eyes don't see anything that look like an actual solution, just a lot of discussion about what transfer rates could or should be. Update: As requested in the comments, I've generated a whole bunch of output from the command line, and put it on Ubuntu Pastebin. Please see it here.

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• Enabling GTX 570

  - by Silas

  Hello i just built up my new system: Asus Rock Z77 Extreme 4 Intel i7 3770k 16 Gb Corsair Ram Zotac Nvidia GTX 570 bequiet! 630W Power supply 120 GB SSD So after i installed UBUNTU 12.04 64 bit. It ran smoothly. I downloaded and installed all the recommended updates. After checking the Sytem details the GTX 570 didnt show up as graphics unit. so i figured i needed to download the drivers. So i did but being a complete newbie to linux i didnt succeed in installing them. (I think) Anyway after several tries and errors i shut down the PC and restarted it. Resultung in do Signal to my screen after trying to reboot and all the monitor outs with no result i took out the graphic card and now it boots normally but after booting it says there is a problem with the system the graphics cant be recognized something something. So Question A: What do i do? I Like linux but the arbitrarity of the Errors that occur without any changes to the system scare me. Question B: Is there A beginners guide to Ubuntu where i could start from scratch because i really want this to work? Question C: Now that the System is (suddently) showing these graphic errors So far without visible consequence despite the error message. should i reinstall the GPU and give the driver installation another try or the other way around? Ill be very grateful for any help. Thank you in advance!

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• Dual boot problem with ubuntu 12.04 and Vista

  - by vendella dahlahdoo

  Greetings from New Zealand. I have installed Microsoft Windows Vista and then installed Ubuntu 12.04 on my refurbished Compaq nx8220 laptop. I get the following infamous head hurting prompt continually. error: no such partition. grub rescue> Have tried most of the common recommended solutions. Live-CD then install Boot-Repair through the Terminal didn't work. It repaired all the linux stuff when restoring grub and then can't boot into Windows Vista. When I use Boot-Repair to fix the MBR, then I can't boot into Ubuntu. Tried installing BCD 2.1 in Vista and tried all the options one after another in BCD. Still no Ubuntu when selected through the options menu from BCD on restart/reboot. I have tried the boot repair option on the Ubuntu server CD-ROM, tried installing earlier versions of Ubuntu 11.04, 11.10, and Ubuntu server 11.10 and 12.04. Still the same result. I tried deleting the Ubuntu partitions through Vista a number of times and reinstalling Ubuntu. I have been trying and retrying all the options in Boot-Repair in different combinations for the past week and a half. I have tried at least 10 times installing and reinstalling Ubuntu. I really love Ubuntu and believe I have exhausted most of the recommended solutions and have spent too much time on this. Its driving me nuts!! please can someone help, I have finally given up (sigh). The following are some outputs from Boot-Repair from my last attempts. http://paste.ubuntu.com/1019227 http://paste.ubuntu.com/1019264 I was only allowed to post two links being a newbie. The only thing left for me to do is the flying Samoan dropkick laptop trick. Thanks in advance. Francis.

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• ubuntu boots only with usb

  - by klimat

  Just installed Ubuntu 11.04. But it boots only from usb. Seems like I didn't pay attention during selecting boot device. sudo fdisk -l [sudo] password for klim: Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x000177e1 Device Boot Start End Blocks Id System /dev/sda1 1 60045 482302976 83 Linux /dev/sda2 60045 60802 6080513 5 Extended Partition 2 does not start on physical sector boundary. /dev/sda5 60045 60802 6080512 82 Linux swap / Solaris Disk /dev/sdb: 4004 MB, 4004511744 bytes 124 heads, 62 sectors/track, 1017 cylinders Units = cylinders of 7688 * 512 = 3936256 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000eee1a Device Boot Start End Blocks Id System /dev/sdb1 * 1 1017 3909317 b W95 FAT32 grub updating or another "grub" operations don't work as I've tried. Can I just copy whole boot folder from usb to HD or smth like that? Any kind of help is appreciated. Apologize for my newbie skills.

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• Setting up a network between a host and guest virtual machine

  - by anonymous

  (I'm running ubuntu server 12.04 on virtual box) I'm trying to transfer a file (scp) from my laptop to one of the directories of a virtual machine. I tried sharing folders, but that failed. I'm a bit of a networking newbie. I've looked at like 20-30 pages. Here's one: http://www.howtoforge.com/moving-files-between-linux-systems-with-scp I followed those steps exactly. My problem is that when I try using scp, it just hangs. I'm also not sure which network interface to configure (eth0, eth1?) in the guest OS. Another (significant?) detail is that the inet address of eth0 is 10.0.2.15 instead of something like 192.168.x.y. I've enabled the bridge adapter and the host-only adapter. Both the laptop and guest VM have openssh-server installed. I'm not sure what to do at this point. Is there a better place to ask about this?

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• Using "gedit", a string of errors occours

  - by Kumuluzz

  I'm trying to program some small programs in C in terminal and gedit. But everytime i use gedit then a string of errors occours. When i open a new file nothing happens. But in the exact same moment i save the file, then a string of erros coour. Also if i open an already existing file (not a new one), then when the gedit window opens the old file all the lines of errors are writen. In both cases in less than a second and nothing more happens. An example to the error: "error: line 35272: 0 is wrong flag id". They are all similar to this, except the line number is different. There are like 50 of them. I'm running 11.10, just installed it a couple of days again (yes, i'm a newbie) and i've updated all the files recently. I've tried reinstalling gedit via: sudo apt-get --reinstall install gedit It kinda made it worse, now a lot of the lines are shown twice. So now it goes (this is a copy of the first lines of error): error: line 6787: 0 is wrong flag id error: line 10034: 0 is wrong flag id error: line 10034: 0 is wrong flag id error: line 11351: 0 is wrong flag id error: line 11351: 0 is wrong flag id error: line 11849: 0 is wrong flag id error: line 11849: 0 is wrong flag id error: line 15609: 0 is wrong flag id error: line 15609: 0 is wrong flag id error: line 19814: 0 is wrong flag id

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• Install Problems on ASUS X401A Notebook

  - by tired_of_trying

  okay... I tried many approaches to install Ubuntu 12.xxx on my new Asus notebook with varying degrees of failure... First: I'm not a newbie but I'm as frustrated as one! Install background: Install from USB DVD drive: The install went well. Re-booted machine. choose ubuntu and it errors with a MBR file error (can't remember the exact wording - something to do with missing the file. Choosing to boot W7 works fine. Install from USB Stick: Couldn't get machine to recognize the .iso Install into Oracle's Vbox: Got the boot splash screen, then hangs with a zillion errors. Note: I didn't have any problems installing ubuntu in Vbox on my iMac and it run's great. Installed using wubi: Installed fine but get errors when booting ubuntu (it doesn't find the needed wubi files). I downloaded to the C: drive and tried installing from there - no luck. For kicks: I tried running Slax Linux .iso from a USB stick and it runs fine. Some Questions: Did I use the correct .iso? (I tried 12.04.0 and 12.04.1 both 32 and 64 bit versions. I simply downloaded them from the download link and didn't use/look for an alternate version. Do I need to do something special when burning the .iso to disc? What? I did read tons of posts but, no luck with finding the solution. Any help is appreciated... thanks

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• ubuntu 12.04 will not play DVDs

  - by ayelet

  First off, I'm not just a newbie, I'm clueless! So your answers will need to be in complete idiot language (let's say I'm computer saavy, and I can follow directions,but I've never programmed anything and assume I don't understand any abbreviations. So why am I running linux? b/c windows was driving me nuts!! and my friend convinced me. day-to-day operations, we're doing fine, but when it comes to problems, I've got no clue what I'm doing!) So here's what's going on, my machine is an HP pavilion dv6, my optical drive is a standard cd/dvdrw, when i load an audio cd of any type (burned, official, etc,..) I have no problems, when I pop in a dvd - i get nothing. the dvd icon comes up in my launch tray, when I open VLC player I can find the dvd in the folder... but it won't play. I can watch movies I've downloaded with no problem, I can also watch movies off an external hard drive. The only thing I've tried is removing vlc and reinstalling, and I tried installing a different player (gnome maybe? I don't remember). none of that worked. Again, i can follow directions, but you need to be very specific and don't assume I know anything going in. (I mean, I know basic stuff, but nothing too technical.) PLEASE HELP!!! MY KIDS ARE DRIVING ME CRAZY!!! Thanks!!

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• Extremely slow desktop and laggy. Need help with graphics driver

  - by user171624

  I am a fresh newbie Ubuntu user and I just installed my first Ubuntu 13.04 onto my HP Slate 2. I did a liveCD on my USB drive and installed everything perfectly fine...nice and smooth, not a trace of lag. Then I rebooted using Ubuntu itself on the computer, it was extremely slow and laggy. Icons or any buttons doesn't trigger right away, the performance of the entire thing looks like either 0.25 fps to 1 fps. My HP Slate 2 information: Processor: Intel Atom Z670 1.5Ghz Memory Ram: 2.0 GB Videocard: Intel GMA 600 (PowerVr SGX535) SolidStateDrive(SSD): 32GB I tried installing the intel linux graphics driver and it failed to install because it said I don't have any intel based graphics card. Well...I do as you see above. What can I do? I can't get on the internet on it, I'm using my primary computer (Windows 7) to do all the searchings and put the files onto the USB to move it over to my tablet. Simply...I don't get it...using liveCD on USB, it was all nice and smooth...then after the installation...BOOM! Slow, laggy, and etc. Can anyone help me? Thanks!

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• Please help me debug this little C program on dynamic two-dimensional array? [migrated]

  - by azhi

  I am a newbie here. I have written a little C program, which is to create a two-dimensional matrix. Here is the code: #include <stdio.h> #include <stdlib.h> int **CreatMatrix(int m,int n){ int **Matrix; int i; Matrix=(int**)malloc(m*sizeof(int*)); for(i=0;i<m;i++){ Matrix[i]=(int*)malloc(n*sizeof(int)); } return Matrix; } int main(){ int m,n; int **A; printf("Please input the size of the Matrix: "); scanf("%d%d",&m,&n); A=CreatMatrix(m,n); printf("Please input the entries of the Matrix, which should be integers!\n"); int i,j; for(i=0;i<m;i++){ for(j=0;j<n;j++){ scanf("%d",&A[i][j]); } } printf("The Matrix that you input is:\n"); for(i=0;i<m;i++){ for(j=0;j<n;j++){ printf("%3d ",A[i][j]); } printf("\n"); } for(i=0;i<m;i++) free(A[i]); free(A); } I have run it, and it works fine. But I am not sure if it is right? Can anyone help me debug it?

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• How to recover lost files after an install

  - by Gentry McColm

  I'm a newbie learning along the way. I recently installed a 2nd hdd into my ubuntu box. Have one of about 160g which runs ubuntu 12.04. And the new hdd was 1 tb, used for holding videos. I had set up 2nd drive as ext3 I believe. And set up folders on it to hold the videos. Worked great. Also thought I had set it up for auto mount. I was able to read and write on it. Etc. Computer froze, so had to reboot it. When I did, system would not reboot: hung on the Ubuntu screen with 5 dots. I hit a few buttons and the command screen showed up, indicating that my 2nd hdd would not mount. Stopped up whole system. Tried rebooting, no go. Had to reinstall ubuntu on the 1st hdd. Did not apparently touch the 2nd one. Well, when I got it up and running, my 2nd hdd mounted automatically (yeah!), but now I cannot find my videos I already had on it. I had not put any more than about 30g of videos on it, but now when I read its Properties, it says I'm using about 50g. So, I'm wondering if somewhere in that, buried, are my 17 videos. Any help in recovering this? Thanks!

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• CentOS drive mapping? [on hold]

  - by DroidOS

  This is the first time I am posting on this particular StackExchange forum and I hope that I am using the right one for the present question. Briefly, this is what I need to do I am running a web service where users can, amongst other things, upload and store files on the server. What I want to do is to hive off user file storage to a different location so my server (CentOS 64 bit) can concentrate on what it does best - server side scripting and database management. As things stand all user files go into subdirectories in a folder called stash that lies above DOC_ROOT. What I would like to do is Transparently detect all attempts to read/write to stash/sub_folder and get/set file data on a remote server - ideally the latter would be one which replicates files like a CDN so they can be delivered from the closest/fastest location based on where the user's location. Even nicer would be if for all read accesses I could provide a URL that allows the user's browser to fetch the relevant file directly without having to funnel them via my server. I am a relative newbie when it comes to this sort of thing so I hope that I have phrased this question adequately well. From the little searching I done I gathered that WebDAV can be used to map drives to a different location on the web so perhaps that is a starting point. But if that will work I need to Establish how to get WebDAV up and running on my CentOS 64 bit server. Ideally, identify a service that allows this kind of file storage and provides an API I can use in my own scripting. I'd much appreciate any help with this.

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• Separate update and render

  - by NSAddict

  I'm programming a simple Snake in Java. I'm a complete newbie when it comes to Java and Game Developing, so please bear with me ;) Until now, I have been using a UI thread, as well as a update-thread. The update thread just set the position, set the GameObjects, and so on. I didn't think much of concurrency, but now I've come to a problem. I wanted to modify the ArrayList<GameObject>, but it throws a java.util.ConcurrentModificationException. With a little research I found out that this happens because the two threads are trying to access the variables at the same time. But I didn't really find a way to prevent this. I thought about copying the array and swapping them out when the rendering is finished, but I would have to deep-copy them, which isn't really the best solution in my opinion. It probably eats up more CPU resources than a single-threaded game. Are there any other ways to prevent this? Thanks a lot for your help!

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• Can't connect to Wireless

  - by SimplyRed37

  Good day all! I hope you are doing good. I have performed a WUBI installation of 12.04 on my HP G62 laptop, which has an Atheros AR9285 wireless chipset. Everything works fine with my wired network connection. However, wireless is unable to connect to my wifi network. I enter the WPA2 key and then it attemps to connect, but eventually comes back, asking for the WPA2 key again, as if it was not good. All of the other laptops in the household are able to connect, using the same key (I configured them all, so I am 500% sure of the WPA2 key). Any idea as to what could be causing this? I can definitely post the output of CLI commands like "rfkill list" or "sudo lshw -class network", or "ifconfig". I have installed Ubuntu a few time but I am definitely still a newbie, but I am definitely computer savyy. Looking forward to suggestions . Thanks in advance !!! Dan...

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• Qml and QfileSystemModel interaction problem

  - by user136432

  I'm having some problem in realizing an interaction between QML and C++ to obtain a very basic file browser that is shown within a ListView. I tried to use as model for my data the QT class QFileSystemModel, but it did't work as I expected, probably I didn't fully understand the QT class documentation about the use of this model or the example I found on the internet. Here is the code that I am using: File main.cpp #include <QModelIndex> #include <QFileSystemModel> #include <QQmlContext> #include <QApplication> #include "qtquick2applicationviewer.h" int main(int argc, char *argv[]) { QApplication app(argc, argv); QFileSystemModel* model = new QFileSystemModel; model->setRootPath("C:/"); model->setFilter(QDir::Files | QDir::AllDirs); QtQuick2ApplicationViewer viewer; // Make QFileSystemModel* available for QML use. viewer.rootContext()->setContextProperty("myFileModel", model); viewer.setMainQmlFile(QStringLiteral("qml/ProvaQML/main.qml")); viewer.showExpanded(); return app.exec(); } File main.qml Rectangle { id: main width: 800 height: 600 ListView { id: view property string root_path: "C:/Users" x: 40 y: 20 width: parent.width - (2*x) height: parent.height - (2*y) VisualDataModel { id: myVisualModel model: myFileModel // Get the model QFileSystemModel exposed from C++ delegate { Rectangle { width: 210; height: 20; radius: 5; border.width: 2; border.color: "orange"; color: "yellow"; Text { text: fileName; x: parent.x + 10; } MouseArea { anchors.fill: parent onDoubleClicked: { myVisualModel.rootIndex = myVisualModel.modelIndex(index) } } } } } highlight: Rectangle { color: "lightsteelblue"; radius: 5 } focus: true } } The first problem with this code is that first elements that I can see within my list are my PC logical drives even if I set a specific path. Then when I first double click on drive "C:\" it shows the list of files and directories on that path, but when I double click on a directory a second time the screen flickers for one moment and then it shows again the PC logical drives. Can anyone tell me how should I use the QFileSystemModel class with a ListView QML object? Thanks in advance! Carlo

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• Problems Rendering Text in OpenGL Using FreeType

  - by Sean M.

  I've been following both the FreeType2 tutorial and the WikiBooks tuorial, trying to combine things from them both in order to load and render fonts using the FreeType library. I used the font loading code from the FreeType2 tutorial and tried to implement the rendering code from the wikibooks tutorial (tried being the keyword as I'm still trying to learn model OpenGL, I'm using 3.2). Everything loads correctly and I have the shader program to render the text with working, but I can't get the text to render. I'm 99% sure that it has something to do with how I cam passing data to the shader, or how I set up the screen. These are the code segments that handle OpenGL initialization, as well as Font initialization and rendering: //Init glfw if (!glfwInit()) { fprintf(stderr, "GLFW Initialization has failed!\n"); exit(EXIT_FAILURE); } printf("GLFW Initialized.\n"); //Process the command line arguments processCmdArgs(argc, argv); //Create the window glfwWindowHint(GLFW_SAMPLES, g_aaSamples); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); g_mainWindow = glfwCreateWindow(g_screenWidth, g_screenHeight, "Voxel Shipyard", g_fullScreen ? glfwGetPrimaryMonitor() : nullptr, nullptr); if (!g_mainWindow) { fprintf(stderr, "Could not create GLFW window!\n"); closeOGL(); exit(EXIT_FAILURE); } glfwMakeContextCurrent(g_mainWindow); printf("Window and OpenGL rendering context created.\n"); glClearColor(0.2f, 0.2f, 0.2f, 1.0f); //Are these necessary for Modern OpenGL (3.0+)? glViewport(0, 0, g_screenWidth, g_screenHeight); glOrtho(0, g_screenWidth, g_screenHeight, 0, -1, 1); //Init glew int err = glewInit(); if (err != GLEW_OK) { fprintf(stderr, "GLEW initialization failed!\n"); fprintf(stderr, "%s\n", glewGetErrorString(err)); closeOGL(); exit(EXIT_FAILURE); } printf("GLEW initialized.\n"); Here is the font file (it's slightly too big to post): CFont.h/CFont.cpp Here is the solution zipped up: [solution] (https://dl.dropboxusercontent.com/u/36062916/VoxelShipyard.zip), if anyone feels they need the entire solution. If anyone could take a look at the code, it would be greatly appreciated. Also if someone has a tutorial that is a little more user friendly, that would also be appreciated. Thanks.

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• Segmentation fault 11 in MacOS X- C++ [migrated]

  - by Marcos Cesar Vargas Magana

  all. I have a "segmentation fault 11" error when I run the following code. The code actually compiles but I get the error at run time. //** Terror.h ** #include <iostream> #include <string> #include <map> using std::map; using std::pair; using std::string; template<typename Tsize> class Terror { public: //Inserts a message in the map. static Tsize insertMessage(const string& message) { mErrorMessages.insert( pair<Tsize, string>(mErrorMessages.size()+1, message) ); return mErrorMessages.size(); } private: static map<Tsize, string> mErrorMessages; } template<typename Tsize> map<Tsize,string> Terror<Tsize>::mErrorMessages; //** error.h ** #include <iostream> #include "Terror.h" typedef unsigned short errorType; typedef Terror<errorType> error; errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); //** main.cpp ** #include <iostream> #include "error.h" using namespace std; int main() { try { throw error(memoryAllocationError); } catch(error& err) { } } I have kind of debugging the code and the error happens when the message is being inserted in the static map member. An observation is that if I put the line: errorType memoryAllocationError=error::insertMessage("ERROR: out of memory."); inside the "main()" function instead of at global scope, then everything works fine. But I would like to extend the error messages at global scope, not at local scope. The map is defined static so that all instances of "error" share the same error codes and messages. Do you know how can I get this or something similar. Thank you very much.

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• What are some reasonable stylistic limits on type inference?

  - by Jon Purdy

  C++0x adds pretty darn comprehensive type inference support. I'm sorely tempted to use it everywhere possible to avoid undue repetition, but I'm wondering if removing explicit type information all over the place is such a good idea. Consider this rather contrived example: Foo.h: #include <set> class Foo { private: static std::set<Foo*> instances; public: Foo(); ~Foo(); // What does it return? Who cares! Just forward it! static decltype(instances.begin()) begin() { return instances.begin(); } static decltype(instances.end()) end() { return instances.end(); } }; Foo.cpp: #include <Foo.h> #include <Bar.h> // The type need only be specified in one location! // But I do have to open the header to find out what it actually is. decltype(Foo::instances) Foo::instances; Foo() { // What is the type of x? auto x = Bar::get_something(); // What does do_something() return? auto y = x.do_something(*this); // Well, it's convertible to bool somehow... if (!y) throw "a constant, old school"; instances.insert(this); } ~Foo() { instances.erase(this); } Would you say this is reasonable, or is it completely ridiculous? After all, especially if you're used to developing in a dynamic language, you don't really need to care all that much about the types of things, and can trust that the compiler will catch any egregious abuses of the type system. But for those of you that rely on editor support for method signatures, you're out of luck, so using this style in a library interface is probably really bad practice. I find that writing things with all possible types implicit actually makes my code a lot easier for me to follow, because it removes nearly all of the usual clutter of C++. Your mileage may, of course, vary, and that's what I'm interested in hearing about. What are the specific advantages and disadvantages to radical use of type inference?

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• Is anyone doing "real" TDD with Visual-C++, and if yes, how do they do it?

  - by Martin

  Test Driven Development implies writing the test before the code and following a certain cycle: Write Test Check Test (run) Write Production Code Check Test (run) Clean up Production Code Check test (run) As far as I'm concerned, this is only possible if your development solution allows you to very quickly switch between the production and test code, and to execute the test for a certain production code part extremely quickly. Now, while there exist lots of Unit Testing Frameworks for C++ (I'm using Bost.Test atm.) it does seem that there doesn't really exist any decent (for native C++) Visual Studio (Plugin) solution that makes the TDD cycle bearable regardless of framework used. "Bearable" means that it's a one-click action to run a test for a certain cpp file without having to manually set up a separate testing project etc. "Bearable" also means that a simple test starts (linking!) and runs very quickly. So, what tools (plugins) and techniques are out there that make the TDD cycle possible for native C++ development with Visual Studio? Note: I'm fine with free or "commercial" tools. Please: No framework recommendations. (Unless the framework has a dedicated Visual Studio plugin and you want to recommend the plugin.) Edit Note: The answers so far have provided links on how to integrate a Unit Testing framework into Visual Studio. The resources more or less describe how to get the UT framework to compile and get your first Tests running. This is not what this question is about. I'm of the opinion that to really work productively, having the Unit Tests in a manually maintained(!), separate vcproj from your production classes will add so much overhead that TDD "isn't possible". As far as I am aware, you do not add extra "projects" to a Java or C# thing to enable Unit Tests and TDD, and for a good reason. This should be possible with C++ given the right tools, but it seems (this question is about) that there are very little tools for TDD/C++/VS. Googling around, I've found one tool, VisualAssert, that seems to aim in the right direction. However, afaiks, it doesn't seem to be in widespread use (compared to CppUnit, Boost.Test etc.). Edit: I would like to add a comment to the context for this question. I think it does a good summary of outlining (part of) the problem: (comment by Billy ONeal) Visual Studio does not use "build scripts" that are reasonably editable by the user. One project produces one binary. Moreover, Java has the property that Java never builds a complete binary -- the binary you build is just a ZIP of the class files. Therefore it's possible to compile separately then JAR together manually (using e.g. 7z). C++ and C# both actually link their binaries, so generally speaking you can't write a script like that. The closest you can get is to compile everything separately and then do two linkings (one for production, one for testing).

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• What is the correct way to use g_signal_connect() in C++ for dynamic unity quicklists?

  - by hakermania

  I want to make my application use dynamic unity quicklists. For building my application I am using C++ and the QtCreator IDE. When a menu action is triggered I want to be able to have access to a non-static function of my MainWindow class so as to be able to update the Graphical User Interface which can be accessed from inside 'normal' MainWindow's functions. So, I am building up my quicklist like this (mainwindow.cpp): void MainWindow::enable_unity_quicklist(){ Unity_Menu = dbusmenu_menuitem_new(); dbusmenu_menuitem_property_set_bool (Unity_Menu, DBUSMENU_MENUITEM_PROP_VISIBLE, FALSE); Unity_Stop = dbusmenu_menuitem_new(); dbusmenu_menuitem_property_set(Unity_Stop, DBUSMENU_MENUITEM_PROP_LABEL, "Stop"); dbusmenu_menuitem_child_append (Unity_Menu, Unity_Stop); g_signal_connect (Unity_Stop, DBUSMENU_MENUITEM_SIGNAL_ITEM_ACTIVATED, G_CALLBACK(&fake_callback), (gpointer)this); if(!unity_entry) unity_entry = unity_launcher_entry_get_for_desktop_id("myapp.desktop"); unity_launcher_entry_set_quicklist(unity_entry, Unity_Menu); dbusmenu_menuitem_property_set_bool(Unity_Menu, DBUSMENU_MENUITEM_PROP_VISIBLE, true); dbusmenu_menuitem_property_set_bool(Unity_Stop, DBUSMENU_MENUITEM_PROP_VISIBLE, true); } void MainWindow::fake_callback(gpointer data){ MainWindow* m = (MainWindow*)data; m->on_stopButton_clicked(); } void MainWindow::on_stopButton_clicked(){ //stopping the process... } mainwindow.h: private slots: void enable_unity_quicklist(); void on_stopButton_clicked(); public slots: static void fake_callback(gpointer data); This suggestion was taken from http://old.nabble.com/Using-g_signal_connect-in-class-td18461823.html The program crashes immediately after I choose the 'Stop' action from the Unity Quicklist. Debugging the program shows that I am not able to access anything MainWindow related inside the on_stopButton_clicked() without crashing. For example, it crashes when doing this check (which is the first 2 lines of code inside this function): if (!ui->stopButton->isEnabled()) return; I have also tested lots of other things that I found at the internet, but nothing of them worked. One interesting solution would be to use gtkmm (http://developer.gnome.org/gtkmm-tutorial/stable/sec-connecting-signal-handlers.html.en) but I am not used at all working on GTK applications (I work solely in Qt) and I don't know if this even suits to my occasion. A compilable example indicating what the problem is can be found at: http://ubuntuone.com/7iKA3wnPmWVp8YNNDLlVQI (3.2Kb) If you are not familiar with the QtCreator IDE, you can compile with the following commands, as long as you have all the needed libraries: cd dynamic_unity_quicklists_test; qmake -project; qmake; make

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• Why would more CPU cores on virtual machine slow compile times?

  - by Sid

  [edit#2] If anyone from VMWare can hit me up with a copy of VMWare Fusion, I'd be more than happy to do the same as a VirtualBox vs VMWare comparison. Somehow I suspect the VMWare hypervisor will be better tuned for hyperthreading (see my answer too) I'm seeing something curious. As I increase the number of cores on my Windows 7 x64 virtual machine, the overall compile time increases instead of decreasing. Compiling is usually very well suited for parallel processing as in the middle part (post dependency mapping) you can simply call a compiler instance on each of your .c/.cpp/.cs/whatever file to build partial objects for the linker to take over. So I would have imagined that compiling would actually scale very well with # of cores. But what I'm seeing is: 8 cores: 1.89 sec 4 cores: 1.33 sec 2 cores: 1.24 sec 1 core: 1.15 sec Is this simply a design artifact due to a particular vendor's hypervisor implementation (type2:virtualbox in my case) or something more pervasive across more VMs to make hypervisor implementations more simpler? With so many factors, I seem to be able to make arguments both for and against this behavior - so if someone knows more about this than me, I'd be curious to read your answer. Thanks Sid [edit:addressing comments] @MartinBeckett: Cold compiles were discarded. @MonsterTruck: Couldn't find an opensource project to compile directly. Would be great but can't screwup my dev env right now. @Mr Lister, @philosodad: Have 8 hw threads, using VirtualBox, so should be 1:1 mapping without emulation @Thorbjorn: I have 6.5GB for the VM and a smallish VS2012 project - it's quite unlikely that I'm swapping in/out trashing the page file. @All: If someone can point to an open source VS2010/VS2012 project, that might be a better community reference than my (proprietary) VS2012 project. Orchard and DNN seem to need environment tweaking to compile in VS2012. I really would like to see if someone with VMWare Fusion also sees this (for VMWare vs VirtualBox compartmentalization) Test details: Hardware: Macbook Pro Retina CPU : Core i7 @ 2.3Ghz (quad core, hyper threaded = 8 cores in windows task manager) Memory : 16 GB Disk : 256GB SSD Host OS: Mac OS X 10.8 VM type: VirtualBox 4.1.18 (type 2 hypervisor) Guest OS: Windows 7 x64 SP1 Compiler: VS2012 compiling a solution with 3 C# Azure projects Compile times measure by VS2012 plugin called 'VSCommands' All tests run 5 times, first 2 runs discarded, last 3 averaged

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