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• How can I install things in Linux with *no yum* and *no wget*?

  - by e9t

  I'm a newbie to Linux (that mainly uses Windows and Mac OS X) needing some advice. I was trying to install git on a Linux machine today, and encountered some problems: Not knowing the version of the installed OS, I've opened the /proc/version file which said: Linux version 2.6.9-42.0.2.ELsmp ([email protected]) (gcc version 3.4.6 20060404 (Red Hat 3.4.6-3)) #1 SMP Thu Aug 17 17:57:31 EDT 2006 Then, as written in the git documents (http://git-scm.com/download/linux), I assumed I could use the yum install git command for Fedora, but got the following result. [root@myserver ~]# yum install git -bash: yum: command not found So I tried installing yum using wget, but wasn't so lucky. [root@myserver ~]# wget http://linux.duke.edu/projects/yum/download/2.0/yum-2.0.7.tar.gz -bash: wget: command not found I googled and found this page and this page, so tried installing yum with rpm, but only got a result full of question marks. (Possibly an encoding problem, hmm...) [root@myserver ~]# rpm -Uvh http://www.eomy.net/linux/install-yum-x86_64/wget-1.10.2-0.40E.x86_64.rpm http://www.eomy.net/linux/install-yum-x86_64/wget-1.10.2-0.40E.x86_64.rpm(??)?? ?????? ?: /var/tmp/rpm-xfer.TbuAOu: V3 DSA signature: NOKEY, key ID 443e1821 ???.. ########################################### [100%] wget-1.10.2-0.40E U???????g??????? wget-1.10.2-0.40E???? ??g??/usr/bin/wget ?? wget-1.10.2-0.40E U?????? ???? wget-1.10.2-0.40E???? ??g??/usr/share/man/man1/wget.1.gz ?? wget-1.10.2-0.40E U?????? ???? [root@myserver ~]# Finally, when I typed rpm --version in the terminal, I got the below results. [root@myserver ~]# rpm --version RPM ???? - 4.3.3 I would like to know what I can do or possibly try now. Is it not possible to wget or yum anything in my situation? Or is there any magical tool like homebrew (http://mxcl.github.com/homebrew/) that I can use? Any comments or advice would be appreciated. Thanks in advance!

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• How to reference a Domain Controller out of the Local Network?

  - by Adrian

  We have multiple servers scattered over different hosting providers. For learning, experimenting and, ultimately, production purposes, I set one of them as a Domain Controller. That went well, most of our services are now authenticating via AD, which helps us a lot. What I want to do now is to simplify the authentication for the multiple servers, by making each of them look at the Domain Controller. This way, our Devs can log into (Remote Desktop) the multiple servers with the same credentials from AD. I know I have to configure each server to look at the Domain Controller. But when I try to add the Domain Controller to the Computer, it cannot find it, although the Domain Controller address is a valid, reachable internet sub-domain (as in "ad.ourcompany.com"). This is the detailed error message: Note: This information is intended for a network administrator. If you are not your network's administrator, notify the administrator that you received this information, which has been recorded in the file C:\Windows\debug\dcdiag.txt. The following error occurred when DNS was queried for the service location (SRV) resource record used to locate an Active Directory Domain Controller for domain ad.ourcompany.com: The error was: "DNS name does not exist." (error code 0x0000232B RCODE_NAME_ERROR) The query was for the SRV record for _ldap._tcp.dc._msdcs.ad.ourcompany.com Common causes of this error include the following: - The DNS SRV records required to locate a AD DC for the domain are not registered in DNS. These records are registered with a DNS server automatically when a AD DC is added to a domain. They are updated by the AD DC at set intervals. This computer is configured to use DNS servers with the following IP addresses: 109.188.207.9 109.188.207.10 - One or more of the following zones do not include delegation to its child zone: ad.ourcompany.com ourcompany.com com . (the root zone) For information about correcting this problem, click Help. What am I missing? I'm an experienced Dev, but a newbie Sysdamin experimenting with new stuff. Disclaimer All IP addresses and domains/subdomains were changed to preserve security. If by any chance you still can see private information, please let me know so that I can change it.

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• VPN - force a selective range of ip to run on VPN (linux)

  - by Francesco

  Preface: I know there are similar question here and there however I'm a kind of newbie on Net stuff so I need an answer on this specific scenario, hoping that can help others too as it is a common problem Let say I cannot do anything on the local switch to change the local ip range, I don't want to use any complicate trick as use VMachine to hide the local ip range but I want to use net tools to solve the issue. Scenario my local net assign me an IP of this class 192.168.1.xxx (ex. 192.168.1.116) and my VPN (VPNC) assign me IP of same class 192.168.1.xxx (ex. 192.168.1.247) Obviously I need VPN to access local address (ex. 192.168.1.100) but when I open any address of the class 192.168.1.xx the route point to my local net and not to the VPN ones. I'm on linux and i'd like gui solution (network manager) in case it is not possible let play with route command. here what network manager offer me: Here my actual route once connected to the VPN: Here some route information (route -n) Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 0 ppp0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 wlan0 182.71.21.106 192.168.1.1 255.255.255.255 UGH 0 0 0 wlan0 182.71.21.106 192.168.1.1 255.255.255.255 UGH 0 0 0 wlan0 192.168.1.0 0.0.0.0 255.255.255.0 U 9 0 0 wlan0 192.168.1.246 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 Here my ifconfig : ppp0 Link encap:Point-to-Point Protocol inet addr:192.168.1.247 P-t-P:192.168.1.246 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1400 Metric:1 RX packets:3415 errors:0 dropped:0 overruns:0 frame:0 TX packets:2525 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:3682328 (3.6 MB) TX bytes:402315 (402.3 KB) wlan0 Link encap:Ethernet HWaddr 4c:eb:42:06:a3:a6 inet addr:192.168.1.116 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::4eeb:42ff:fe06:a3a6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:72598 errors:0 dropped:0 overruns:0 frame:0 TX packets:42300 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:76000532 (76.0 MB) TX bytes:13919400 (13.9 MB) The Question So basically I would like to add a rule to force this particular address (192.168.1.100) on the VPN and not on my local net

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• SVN: Create a dump file of a folder

  - by DarkJaff

  I'm trying to create a dump file of a folder in my SVN repository.(My goal is to import this dump on another repository, but that's another story). I've read like 20 pages about this and they all tell me to use svndumpfilter but I can't seem to make it work. Here is my command: C:\>svnadmin dump d:/SvnData/TestingSVN/ | svndumpfilter include /TestingSVN/Trunk/Fms/ > d:\FMS.txt The output in the command line is this strange thing: Including prefixes: '/TestingSVN/Trunk/Fms' * Dumped revision 0. Revision 0 com*m iDtutmepde da sr e0v.isi n 1. Revision 1 committed as 1. * Dumped revision 2. Revision 2 committed a*s D2u.mpe revision 3. Revisio*n D3u mcpoemdm irtetveids iaosn 34.. Revision* 4D ucmopmemdi trteevdi saiso n4 .5. Revision 5 com*m iDtutmepde da sr e5v.isi n 6. Revision 6 commi*t tDeudm paesd 6r.evi ion 7. Revisio*n D7u mcpoemdm irtetveids iaosn 78.. Revision *8 Dcuommpmeidt treedv iassi o8n. 9. Revision 9* cDoummmpietdt erde vaiss i9o.n 1 . Revisi*o nD u1m0p ecdo mrmeivtitseido na s1 11.0 . Revision 11 *c oDmummiptetde dr eavsi s1i1o.n 1 . Revision 12 committed* aDsu m1p2e.d r vision 13. Revision 13 committ*e dD uamsp e1d3 .rev sion 14. Revision 14 commit*t eDdu mapse d1 4r.evi ion 15. Revision 15 committed as 15. * Dumped revision 16. Revision 16 committed as 16. Dropped 83 nodes: '/Branches' '/Branches/305' '/Branches/305/New Text Document.txt' '/Fms' '/Fms/ADPropertySheet.cpp'** etc. for 83 nodes... Also, the dump file itself is only 3 kb and contain no real data, only things like that (this is not the complete dump, just a sample) SVN-fs-dump-format-version: 2 UUID: 592fc9f0-5994-e841-a4dc-653714c95216 Revision-number: 0 Prop-content-length: 56 Content-length: 56 K 8 svn:date V 27 2009-06-19T15:05:52.001352Z PROPS-END Revision-number: 1 Prop-content-length: 112 Content-length: 112 K 7 svn:log V 38 This is an empty revision for padding. K 8 svn:date V 27 2009-06-19T15:11:29.378511Z PROPS-END Can anybody help me sort this out?

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• Qt4: QPrinter / QPainter only prints the first document

  - by hurikhan77

  The problem is that my application only prints the first document fine. The second document is empty, only the page number is printed, the rest of the page is empty. In Qt4, I'm initializing the printer in the main.cpp in the following way: mw->printer = new QPrinter(QPrinter::HighResolution); mw->printer->setPaperSize(QPrinter::A5); mw->printer->setNumCopies(2); mw->printer->setColorMode(QPrinter::GrayScale); QPrintDialog *dialog = new QPrintDialog(mw->printer, mw); dialog->setWindowTitle(QObject::tr("Printer Setup")); if (dialog->exec() == QDialog::Accepted) { mw->printer->setFullPage(TRUE); return a.exec (); } This works fine for printing the first document from the application: qDebug("Printing"); QPainter p; if (!p.begin(printer)) { qDebug("Printing aborted"); return; } Q3PaintDeviceMetrics metrics(p.device()); int dpiy = metrics.logicalDpiY(); int dpix = metrics.logicalDpiX(); int tmargin = (int) ((marginTop / 2.54) * dpiy); int bmargin = (int) ((marginBottom / 2.54) * dpiy); int lmargin = (int) ((marginLeft / 2.54) * dpix); int rmargin = (int) ((marginRight / 2.54) * dpix); QRect body(lmargin, tmargin, metrics.width() - (lmargin + rmargin), metrics.height() - (tmargin + bmargin)); QString document; /* ... app logic to write a richtext document */ Q3SimpleRichText richText(QString("<qt>%1</qt>").arg(document), QFont("Arial", fontSize)); richText.setWidth(&p, body.width()); QRect view(body); int page = 1; do { // draw text richText.draw(&p, body.left(), body.top(), view, colorGroup()); view.moveBy(0, body.height()); p.translate(0, -body.height()); // insert page number p.drawText(view.right() - p.fontMetrics().width(QString::number(page)), view.bottom() + p.fontMetrics().ascent() + 5, QString::number(page)); // exit loop on last page if (view.top () >= richText.height ()) break; printer->newPage(); page++; } while (TRUE); if (!p.end()) qDebug("Print painter yielded failure"); But when this routine runs the second time, it does not print the document. It will just print an empty page but still with the page number on it. This worked fine before with Qt3.

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• Unable to start auditd

  - by George Reith

  I am on CentOS 5.8 final I recently installed auditd via yum install audit however I am unable to start it. I edited the configuration file to give a verbose output of the error it is recieving in starting up and this is the output: # service auditd start Starting auditd: Config file /etc/audit/auditd.conf opened for parsing log_file_parser called with: /var/log/audit/audit.log log_format_parser called with: RAW log_group_parser called with: root priority_boost_parser called with: 4 flush_parser called with: INCREMENTAL freq_parser called with: 20 num_logs_parser called with: 4 qos_parser called with: lossy dispatch_parser called with: /sbin/audispd name_format_parser called with: NONE max_log_size_parser called with: 5 max_log_size_action_parser called with: ROTATE space_left_parser called with: 75 space_action_parser called with: SYSLOG action_mail_acct_parser called with: root admin_space_left_parser called with: 50 admin_space_left_action_parser called with: SUSPEND disk_full_action_parser called with: SUSPEND disk_error_action_parser called with: SUSPEND tcp_listen_queue_parser called with: 5 tcp_max_per_addr_parser called with: 1 tcp_client_max_idle_parser called with: 0 enable_krb5_parser called with: no GSSAPI support is not enabled, ignoring value at line 30 krb5_principal_parser called with: auditd GSSAPI support is not enabled, ignoring value at line 31 Started dispatcher: /sbin/audispd pid: 3097 type=DAEMON_START msg=audit(1339336882.187:9205): auditd start, ver=1.8 format=raw kernel=2.6.32-042stab056.8 auid=4294967295 pid=3095 res=success config_manager init complete Error setting audit daemon pid (Connection refused) type=DAEMON_ABORT msg=audit(1339336882.189:9206): auditd error halt, auid=4294967295 pid=3095 res=failed Unable to set audit pid, exiting The audit daemon is exiting. Error setting audit daemon pid (Connection refused) [FAILED] The only information I can find online is that this may be due to SELinux, however SELinux is giving me problems of it's own. No matter what I do it appears to be disabled (I want to enable it). The configuration is set to enforced and the server has been rebooted many a time however sestatus still returns SELinux status: disabled. Can anyone shine some light on this problem? EDIT: I don't know if it is related but I noticed the following message appearing in my /var/log/messages Jun 10 16:25:22 s1 iscsid: iSCSI logger with pid=2056 started! Jun 10 16:25:22 s1 iscsid: Missing or Invalid version from /sys/module/scsi_transport_iscsi/version. Make sure a up to date scsi_transport_iscsi module is loaded and a up todate version of iscsid is running. Exiting... I try to start the iSCSI daemon myself (I have not a clue what it does; I am a linux newbie) and I get the following error: Starting iSCSI daemon: FATAL: Could not load /lib/modules/2.6.32-042stab056.8/modules.dep: No such file or directory FATAL: Could not load /lib/modules/2.6.32-042stab056.8/modules.dep: No such file or directory FATAL: Could not load /lib/modules/2.6.32-042stab056.8/modules.dep: No such file or directory FATAL: Could not load /lib/modules/2.6.32-042stab056.8/modules.dep: No such file or directory FATAL: Could not load /lib/modules/2.6.32-042stab056.8/modules.dep: No such file or directory [FAILED] If I go to /lib/modules/ I notice the directory exists but is completely empty.

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• Restart mysql keeping the data

  - by sitonico

  I'm quite new using mysql, so let me know if I'm missing something. I took some holidays, and when I got back to work and I tried to log in phpmyadmin I got a ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2). I never had this problem, so I was browsing to look for a solution. I tried some things, and I'm afraid I touched too much. I couldn't solve the problem, and the I realized that I had some actualizations to be done, and I thought that they may be helpful for mysql. Then I also realized that when I was doing this actualizations first day, they stopped because I had a lack of space, so I restarted then. Then,when the system was configuring mysql, it didn't advance. I waited for a long time and then I just stopped it and restarted the computer. After it, I just tried to uninstall mysql with sudo apt-get remove mysql-server-5.1, and install it again, but it didn't work. Now I have 2 questions: What do you think it is happening? Should I remove mysql completely? What should I do? I'm afraid of losing my databases, is there anyway to recover the data? Thank you very much in advance. -----------EDIT------- These are the messages: alfonso@alfonso-laptop:/$ tail -F /var/log/syslog | grep Feb 15 15:08:01 alfonso-laptop init: mysql post-start process (15192) terminated with status Feb 15 15:08:01 alfonso-laptop init: mysql main process (15263) terminated with status Feb 15 15:08:01 alfonso-laptop init: mysql main process ended, Feb 15 15:08:31 alfonso-laptop init: mysql post-start process (15264) terminated with status Feb 15 15:08:31 alfonso-laptop init: mysql main process (15358) terminated with status Feb 15 15:08:31 alfonso-laptop init: mysql main process ended, Feb 15 15:09:01 alfonso-laptop init: mysql post-start process (15359) terminated with status Feb 15 15:09:01 alfonso-laptop init: mysql main process (15447) terminated with status Feb 15 15:09:01 alfonso-laptop init: mysql main process ended, Feb 15 15:09:32 alfonso-laptop init: mysql post-start process (15448) terminated with status 1 This is the content of error.log-old 110128 13:17:20 [Note] /usr/sbin/mysqld: Normal shutdown 110128 13:17:20 [Note] Event Scheduler: Purging the queue. 0 events 110128 13:17:20 InnoDB: Starting shutdown... 110128 13:17:22 InnoDB: Shutdown completed; log sequence number 0 590872 110128 13:17:22 [Note] /usr/sbin/mysqld: Shutdown complete 110214 2:08:18 [Note] Plugin 'FEDERATED' is disabled. 110214 2:08:19 InnoDB: Started; log sequence number 0 590872 110214 2:08:19 [Note] Event Scheduler: Loaded 0 events 110214 2:08:19 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.1.41-3ubuntu12.8' socket: '/var/run/mysqld/mysqld.sock' port: 3306 (Ubuntu) -- Some links of similar problems https://bugs.launchpad.net/ubuntu/+source/mysql-dfsg-5.1/+bug/573318 http://www.linuxquestions.org/questions/linux-newbie-8/lamp-install-on-lucid-mysqld-sock-missing-mysql-terminating-status%3D1-853152/ It seems it's a permissions problem... But I don't know which permissions I should change... SOLVED -- mysql error 2002 "cannot connect to socket"

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• Undefined symbols for C++0x lambdas?

  - by Austin Hyde

  I was just poking around into some new stuff in C++0x, when I hit a stumbling block: #include <list> #include <cstdio> using namespace std; template <typename T,typename F> void ForEach (list<T> l, F f) { for (typename list<T>::iterator it=l.begin();it!=l.end();++it) f(*it); } int main() { int arr[] = {1,2,3,4,5,6}; list<int> l (arr,arr+6); ForEach(l,[](int x){printf("%d\n",x);}); } does not compile. I get a load of undefined symbol errors. Here's make's output: i386-apple-darwin9-gcc-4.5.0 -std=c++0x -I/usr/local/include -o func main.cpp Undefined symbols: "___cxa_rethrow", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator new(unsigned long)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "___gxx_personality_v0", referenced from: ___gxx_personality_v0$non_lazy_ptr in ccPxxPwU.o "___cxa_begin_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "operator delete(void*)", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::deallocate(std::_List_node<int>*, unsigned long) in ccPxxPwU.o "___cxa_end_catch", referenced from: std::_List_node<int>* std::list<int, std::allocator<int> >::_M_create_node<int const&>(int const&&&) in ccPxxPwU.o "std::__throw_bad_alloc()", referenced from: __gnu_cxx::new_allocator<std::_List_node<int> >::allocate(unsigned long, void const*) in ccPxxPwU.o "std::_List_node_base::_M_hook(std::_List_node_base*)", referenced from: void std::list<int, std::allocator<int> >::_M_insert<int const&>(std::_List_iterator<int>, int const&&&) in ccPxxPwU.o ld: symbol(s) not found collect2: ld returned 1 exit status make: *** [func] Error 1 Why is this not working?

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• Seg Fault when using std::string on an embedded Linux platform

  - by Brad

  Hi, I have been working for a couple of days on a problem with my application running on an embedded Arm Linux platform. Unfortunately the platform precludes me from using any of the usual useful tools for finding the exact issue. When the same code is run on the PC running Linux, I get no such error. In the sample below, I can reliably reproduce the problem by uncommenting the string, list or vector lines. Leaving them commented results in the application running to completion. I expect that something is corrupting the heap, but I cannot see what? The program will run for a few seconds before giving a segmentation fault. The code is compiled using a arm-linux cross compiler: arm-linux-g++ -Wall -otest fault.cpp -ldl -lpthread arm-linux-strip test Any ideas greatly appreciated. #include <stdio.h> #include <vector> #include <list> #include <string> using namespace std; ///////////////////////////////////////////////////////////////////////////// class TestSeg { static pthread_mutex_t _logLock; public: TestSeg() { } ~TestSeg() { } static void* TestThread( void *arg ) { int i = 0; while ( i++ < 10000 ) { printf( "%d\n", i ); WriteBad( "Function" ); } pthread_exit( NULL ); } static void WriteBad( const char* sFunction ) { pthread_mutex_lock( &_logLock ); printf( "%s\n", sFunction ); //string sKiller; // <----------------------------------Bad //list<char> killer; // <----------------------------------Bad //vector<char> killer; // <----------------------------------Bad pthread_mutex_unlock( &_logLock ); return; } void RunTest() { int threads = 100; pthread_t _rx_thread[threads]; for ( int i = 0 ; i < threads ; i++ ) { pthread_create( &_rx_thread[i], NULL, TestThread, NULL ); } for ( int i = 0 ; i < threads ; i++ ) { pthread_join( _rx_thread[i], NULL ); } } }; pthread_mutex_t TestSeg::_logLock = PTHREAD_MUTEX_INITIALIZER; int main( int argc, char *argv[] ) { TestSeg seg; seg.RunTest(); pthread_exit( NULL ); }

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• A mysterious compilation error: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>'

  - by Stephane Rolland

  I wanted to protect the access to a log file that I use for multithreaded logging with boostlog library. I tried this stream class class ThreadSafeStream { public: template <typename TInput> const ThreadSafeStream& operator<< (const TInput &tInput) const { // some thread safe file access return *this; } }; using it this way (text_sink is a boostlog object): //... m_spSink.reset(new text_sink); text_sink::locked_backend_ptr pBackend = m_spSink->locked_backend(); const boost::shared_ptr< ThreadSafeStream >& spFileStream = boost::make_shared<ThreadSafeStream>(); pBackend->add_stream(spFileStream); // this causes the compilation error and I get this mysterious error: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>' the whole compile error: Log.cpp(79): error C2664: 'boost::log2_mt_nt5::sinks::basic_text_ostream_backend<CharT>::add_stream' : cannot convert parameter 1 from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T> &' 1> with 1> [ 1> CharT=char 1> ] 1> and 1> [ 1> T=ThreadSafeStream 1> ] 1> and 1> [ 1> T=std::basic_ostream<char,std::char_traits<char>> 1> ] 1> Reason: cannot convert from 'const boost::shared_ptr<T>' to 'const boost::shared_ptr<T>' 1> with 1> [ 1> T=ThreadSafeStream 1> ] 1> and 1> [ 1> T=std::basic_ostream<char,std::char_traits<char>> 1> ] 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called I suspect that I am not well defining the operator<<()... but I don't find what is wrong.

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• Boost Python - Limits to the number of arguments when wrapping a function

  - by Derek

  I'm using Boost Python to wrap some C++ functions that I've created. One of my C++ functions contains 22 arguments. Boost complains when I try to compile my solution with this function, and I'm trying to figure out if it is just because this function has too many arguments. Does anyone know if such a limit exists? I've copied the error I'm getting below, not the code because I figure someone either knows the answer to this or not - and if there is no limit then I'll just try to figure it out myself. Thanks very much in advance! Here is a copy of the beginning of the error message I receive... 1>main.cpp 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2780: 'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const,Target *)' : expects 2 arguments - 1 provided 1>c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(236) : see declaration of 'boost::python::detail::get_signature' And eventually I get about a hundred copies of error messages very much resembling this one: 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2784: 'boost::mpl::vector17<RT,ClassT&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const)' : could not deduce template argument for 'RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile const' from 'std::string (__cdecl *)(const std::string &,jal::date::JULIAN_DATE,const std::string &,const std::string &,int,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,int,const std::string &,const std::string &,int,const std::string &,const std::string &,const std::string &,const std::string &,const std::string &,int,const std::string &)' 1> c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(218) : see declaration of 'boost::python::detail::get_signature' 1>c:\cpp_ext\boost\boost_1_47\boost\python\make_function.hpp(76): error C2780: 'boost::mpl::vector17<RT,most_derived<Target,ClassT>::type&,T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14> boost::python::detail::get_signature(RT (__thiscall ClassT::* )(T0,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13,T14) volatile,Target *)' : expects 2 arguments - 1 provided 1> c:\cpp_ext\boost\boost_1_47\boost\python\signature.hpp(236) : see declaration of 'boost::python::detail::get_signature'

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• Do you still limit line length in code?

  - by Noldorin

  This is a matter on which I would like to gauge the opinion of the community: Do you still limit the length of lines of code to a fixed maximum? This was certainly a convention of the past for many languages; one would typically cap the number of characters per line to a value such as 80 (and more recnetly 100 or 120 I believe). As far as I understand, the primary reasons for limiting line length are: Readability - You don't have to scroll over horizontally when you want to see the end of some lines. Printing - Admittedly (at least in my experience), most code that you are working on does not get printed out on paper, but by limiting the number of characters you can insure that formatting doesn't get messed up when printed. Past editors (?) - Not sure about this one, but I suspect that at some point in the distant past of programming, (at least some) text editors may have been based on a fixed-width buffer. I'm sure there are points that I am still missing out, so feel free to add to these... Now, when I tend to observe C or C# code nowadays, I often see a number of different styles, the main ones being: Line length capped to 80, 100, or even 120 characters. As far as I understand, 80 is the traditional length, but the longer ones of 100 and 120 have appeared because of the widespread use of high resolutions and widescreen monitors nowadays. No line length capping at all. This tends to be pretty horrible to read, and I don't see it too often, though it's certainly not too rare either. Inconsistent capping of line length. The length of some lines are limited to a fixed maximum (or even a maximum that changes depending on the file/location in code), while others (possibly comments) are not at all. My personal preference here (at least recently) has been to cap the line length to 100 in the Visual Studio editor. This means that in a decently sized window (on a non-widescreen monitor), the ends of lines are still fully visible. I can however see a few disadvantages in this, especially when you end up writing code that's indented 3 or 4 levels and then having to include a long string literal - though I often take this as a sign to refactor my code! In particular, I am curious what the C and C# coders (or anyone who uses Visual Studio for that matter) think about this point, though I would be interested in hearing anyone's thoughts on the subject. Edit Thanks for the all answers - I appreciate the variety of opinions here, all presenting sound reasons. Consensus does seem to be tipping in the direction of always (or almost always) limit the line length. Interestingly, it seems to be in various coding standards to limit the line length. Judging by some of the answers, both the Python and Google CPP guidelines set the limit at 80 chars. I haven't seen anything similar regarding C# or VB.NET, but I would be curious to see if there are ones anywhere.

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• VS 2008 irritating copy constructor link dependency

  - by Paul Hollingsworth

  Hi guys, I've run into the following annoying and seemingly incorrect behaviour in the Visual Studio 2008 C++ compiler: Suppose I have a class library - Car.lib - that uses a "Car" class, with a header called "Car.h": class Car { public: void Drive() { Accelerate(); } void Accelerate(); }; What I'm actually trying to do is use the Car headers (for some other functions), but without having to link with Car.lib itself (the actual class is not called "Car" but I am sanitising this example). If I #include "Car.h" in the .cpp file used to build a managed C++ .dll, but never refer to Car, everything compiles and links fine. This is because I never instantiate a Car object. However, the following: namespace { class Car { public: Car(const Car& rhs) { Accelerate(); } void Accelerate(); }; } leaves me with the link error: Error 2 error LNK2001: unresolved external symbol "public: void __thiscall `anonymous namespace'::Car::Accelerate(void)" (?Accelerate@Car@?A0xce3bb5ed@@$$FQAEXXZ) CREObjectWrapper.obj CREObjectBuilderWrapper Note I've declared the whole thing inside an anonymous namespace so there's no way that the Car functions could be exported from the .DLL in any case. Declaring the copy constructor out-of-line makes no difference. i.e. the following also fails to link: class Car { public: Car(const Car& rhs); void Accelerate(); }; Car::Car(const Car& rhs) { Accelerate(); } It's something specifically to do with the copy constructor note, because the following, for example, does link: class Car { public: Car() { Accelerate(); } void Accelerate(); }; I am not a C++ standards guru but this doesn't seem correct to me. Surely the compiler still should not have had to even generate any code that calls the Car copy constructor. Can anyone confirm if this behaviour is correct? It's been a while since I used C++ - but I don't think this used to be an issue with Visual Studio 6.0 for example. Can anyone suggest a workaround that allows one to "re-use" the Accelerate method from within the copy constructor and still have the copy constructor declared inline?

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• POD global object initialization

  - by paercebal

  I've got bitten today by a bug. The following source can be copy/pasted (and then compiled) into a main.cpp file #include <iostream> // The point of SomeGlobalObject is for its // constructor to be launched before the main // ... struct SomeGlobalObject { SomeGlobalObject() ; } ; // ... // Which explains the global object SomeGlobalObject oSomeGlobalObject ; // A POD... I was hoping it would be constructed at // compile time when using an argument list struct MyPod { short m_short ; const char * const m_string ; } ; // declaration/Initialization of a MyPod array MyPod myArrayOfPod[] = { { 1, "Hello" }, { 2, "World" }, { 3, " !" } } ; // declaration/Initialization of an array of array of void * void * myArrayOfVoid[][2] = { { (void *)1, "Hello" }, { (void *)2, "World" }, { (void *)3, " !" } } ; // constructor of the global object... Launched BEFORE main SomeGlobalObject::SomeGlobalObject() { std::cout << "myArrayOfPod[0].m_short : " << myArrayOfPod[0].m_short << std::endl ; std::cout << "myArrayOfVoid[0][0] : " << myArrayOfVoid[0][0] << std::endl ; } // main... What else ? int main(int argc, char* argv[]) { return 0 ; } MyPod being a POD, I believed there would be no constructors. Only initialization at compile time. Thus, the global object SomeGlobalObject would have no problem to use the global array of PODs upon its construction. The problem is that in real life, nothing is so simple. On Visual C++ 2008 (I did not test on other compilers), upon execution myArrayOfPodis not initialized, even ifmyArrayOfVoid` is initialized. So my questions is: Are C++ compilers not supposed to initialize global PODs (including POD structures) at compilation time ? Note that I know global variable are evil, and I know that one can't be sure of the order of creation of global variables declared in different compilation units. The problem here is really the POD C-like initialization which seems to call a constructor (the default, compiler-generated one?). And to make everyone happy: This is on debug. On release, the global array of PODs is correctly initialized.

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• How to write a cctor and op= for a factory class with ptr to abstract member field?

  - by Kache4

  I'm extracting files from zip and rar archives into raw buffers. I created the following to wrap minizip and unrarlib: Archive.hpp #include "ArchiveBase.hpp" #include "ArchiveDerived.hpp" class Archive { public: Archive(string path) { /* logic here to determine type */ switch(type) { case RAR: archive_ = new ArchiveRar(path); break; case ZIP: archive_ = new ArchiveZip(path); break; case UNKNOWN_ARCHIVE: throw; break; } } Archive(Archive& other) { archive_ = // how do I copy an abstract class? } ~Archive() { delete archive_; } void passThrough(ArchiveBase::Data& data) { archive_->passThrough(data); } Archive& operator = (Archive& other) { if (this == &other) return *this; ArchiveBase* newArchive = // can't instantiate.... delete archive_; archive_ = newArchive; return *this; } private: ArchiveBase* archive_; } ArchiveBase.hpp class ArchiveBase { public: // Is there any way to put this struct in Archive instead, // so that outside classes instantiating one could use // Archive::Data instead of ArchiveBase::Data? struct Data { int field; }; virtual void passThrough(Data& data) = 0; /* more methods */ } ArchiveDerived.hpp "Derived" being "Zip" or "Rar" #include "ArchiveBase.hpp" class ArchiveDerived : public ArchiveBase { public: ArchiveDerived(string path); void passThrough(ArchiveBase::Data& data); private: /* fields needed by minizip/unrarlib */ // example zip: unzFile zipFile_; // example rar: RARHANDLE rarFile_; } ArchiveDerived.cpp #include "ArchiveDerived.hpp" ArchiveDerived::ArchiveDerived(string path) { //implement } ArchiveDerived::passThrough(ArchiveBase::Data& data) { //implement } Somebody had suggested I use this design so that I could do: Archive archiveFile(pathToZipOrRar); archiveFile.passThrough(extractParams); // yay polymorphism! How do I write a cctor for Archive? What about op= for Archive? What can I do about "renaming" ArchiveBase::Data to Archive::Data? (Both minizip and unrarlib use such structs for input and output. Data is generic for Zip & Rar and later is used to create the respective library's struct.)

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• Qt4: QPrinter / QPainter only print the first document

  - by hurikhan77

  In Qt4, I'm initializing the printer in the main.cpp in the following way: mw->printer = new QPrinter(QPrinter::HighResolution); mw->printer->setPaperSize(QPrinter::A5); mw->printer->setNumCopies(2); mw->printer->setColorMode(QPrinter::GrayScale); QPrintDialog *dialog = new QPrintDialog(mw->printer, mw); dialog->setWindowTitle(QObject::tr("Printer Setup")); if (dialog->exec() == QDialog::Accepted) { mw->printer->setFullPage(TRUE); return a.exec (); } This works fine for printing the first document from the application: qDebug("Printing"); QPainter p; if (!p.begin(printer)) { qDebug("Printing aborted"); return; } Q3PaintDeviceMetrics metrics(p.device()); int dpiy = metrics.logicalDpiY(); int dpix = metrics.logicalDpiX(); int tmargin = (int) ((marginTop / 2.54) * dpiy); int bmargin = (int) ((marginBottom / 2.54) * dpiy); int lmargin = (int) ((marginLeft / 2.54) * dpix); int rmargin = (int) ((marginRight / 2.54) * dpix); QRect body(lmargin, tmargin, metrics.width() - (lmargin + rmargin), metrics.height() - (tmargin + bmargin)); QString document; /* ... app logic to write a richtext document */ Q3SimpleRichText richText(QString("<qt>%1</qt>").arg(document), QFont("Arial", fontSize)); richText.setWidth(&p, body.width()); QRect view(body); int page = 1; do { // draw text richText.draw(&p, body.left(), body.top(), view, colorGroup()); view.moveBy(0, body.height()); p.translate(0, -body.height()); // insert page number p.drawText(view.right() - p.fontMetrics().width(QString::number(page)), view.bottom() + p.fontMetrics().ascent() + 5, QString::number(page)); // exit loop on last page if (view.top () >= richText.height ()) break; printer->newPage(); page++; } while (TRUE); if (!p.end()) qDebug("Print painter yielded failure"); But when this routine runs the second time, it does not print the document. It will just print an empty page but still with the page number on it. This worked fine before with Qt3.

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• C++ - Conway's Game of Life & Stepping Backwards

  - by Gabe

  I was able to create a version Conway's Game of Life that either stepped forward each click, or just ran forward using a timer. (I'm doing this using Qt.) Now, I need to be able to save all previous game grids, so that I can step backwards by clicking a button. I'm trying to use a stack, and it seems like I'm pushing the old gridcells onto the stack correctly. But when I run it in QT, the grids don't change when I click BACK. I've tried different things for the last three hours, to no avail. Any ideas? gridwindow.cpp - My problem should be in here somewhere. Probably the handleBack() func. #include <iostream> #include "gridwindow.h" using namespace std; // Constructor for window. It constructs the three portions of the GUI and lays them out vertically. GridWindow::GridWindow(QWidget *parent,int rows,int cols) : QWidget(parent) { QHBoxLayout *header = setupHeader(); // Setup the title at the top. QGridLayout *grid = setupGrid(rows,cols); // Setup the grid of colored cells in the middle. QHBoxLayout *buttonRow = setupButtonRow(); // Setup the row of buttons across the bottom. QVBoxLayout *layout = new QVBoxLayout(); // Puts everything together. layout->addLayout(header); layout->addLayout(grid); layout->addLayout(buttonRow); setLayout(layout); } // Destructor. GridWindow::~GridWindow() { delete title; } // Builds header section of the GUI. QHBoxLayout* GridWindow::setupHeader() { QHBoxLayout *header = new QHBoxLayout(); // Creates horizontal box. header->setAlignment(Qt::AlignHCenter); this->title = new QLabel("CONWAY'S GAME OF LIFE",this); // Creates big, bold, centered label (title): "Conway's Game of Life." this->title->setAlignment(Qt::AlignHCenter); this->title->setFont(QFont("Arial", 32, QFont::Bold)); header->addWidget(this->title); // Adds widget to layout. return header; // Returns header to grid window. } // Builds the grid of cells. This method populates the grid's 2D array of GridCells with MxN cells. QGridLayout* GridWindow::setupGrid(int rows,int cols) { isRunning = false; QGridLayout *grid = new QGridLayout(); // Creates grid layout. grid->setHorizontalSpacing(0); // No empty spaces. Cells should be contiguous. grid->setVerticalSpacing(0); grid->setSpacing(0); grid->setAlignment(Qt::AlignHCenter); for(int i=0; i < rows; i++) //Each row is a vector of grid cells. { std::vector<GridCell*> row; // Creates new vector for current row. cells.push_back(row); for(int j=0; j < cols; j++) { GridCell *cell = new GridCell(); // Creates and adds new cell to row. cells.at(i).push_back(cell); grid->addWidget(cell,i,j); // Adds to cell to grid layout. Column expands vertically. grid->setColumnStretch(j,1); } grid->setRowStretch(i,1); // Sets row expansion horizontally. } return grid; // Returns grid. } // Builds footer section of the GUI. QHBoxLayout* GridWindow::setupButtonRow() { QHBoxLayout *buttonRow = new QHBoxLayout(); // Creates horizontal box for buttons. buttonRow->setAlignment(Qt::AlignHCenter); // Clear Button - Clears cell; sets them all to DEAD/white. QPushButton *clearButton = new QPushButton("CLEAR"); clearButton->setFixedSize(100,25); connect(clearButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Pauses timer before clearing. connect(clearButton, SIGNAL(clicked()), this, SLOT(handleClear())); // Connects to clear function to make all cells DEAD/white. buttonRow->addWidget(clearButton); // Forward Button - Steps one step forward. QPushButton *forwardButton = new QPushButton("FORWARD"); forwardButton->setFixedSize(100,25); connect(forwardButton, SIGNAL(clicked()), this, SLOT(handleForward())); // Signals to handleForward function.. buttonRow->addWidget(forwardButton); // Back Button - Steps one step backward. QPushButton *backButton = new QPushButton("BACK"); backButton->setFixedSize(100,25); connect(backButton, SIGNAL(clicked()), this, SLOT(handleBack())); // Signals to handleBack funciton. buttonRow->addWidget(backButton); // Start Button - Starts game when user clicks. Or, resumes game after being paused. QPushButton *startButton = new QPushButton("START/RESUME"); startButton->setFixedSize(100,25); connect(startButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Deletes current timer if there is one. Then restarts everything. connect(startButton, SIGNAL(clicked()), this, SLOT(handleStart())); // Signals to handleStart function. buttonRow->addWidget(startButton); // Pause Button - Pauses simulation of game. QPushButton *pauseButton = new QPushButton("PAUSE"); pauseButton->setFixedSize(100,25); connect(pauseButton, SIGNAL(clicked()), this, SLOT(handlePause())); // Signals to pause function which pauses timer. buttonRow->addWidget(pauseButton); // Quit Button - Exits program. QPushButton *quitButton = new QPushButton("EXIT"); quitButton->setFixedSize(100,25); connect(quitButton, SIGNAL(clicked()), qApp, SLOT(quit())); // Signals the quit slot which ends the program. buttonRow->addWidget(quitButton); return buttonRow; // Returns bottom of layout. } /* SLOT method for handling clicks on the "clear" button. Receives "clicked" signals on the "Clear" button and sets all cells to DEAD. */ void GridWindow::handleClear() { for(unsigned int row=0; row < cells.size(); row++) // Loops through current rows' cells. { for(unsigned int col=0; col < cells[row].size(); col++) // Loops through the rows'columns' cells. { GridCell *cell = cells[row][col]; // Grab the current cell & set its value to dead. cell->setType(DEAD); } } } /* SLOT method for handling clicks on the "start" button. Receives "clicked" signals on the "start" button and begins game simulation. */ void GridWindow::handleStart() { isRunning = true; // It is running. Sets isRunning to true. this->timer = new QTimer(this); // Creates new timer. connect(this->timer, SIGNAL(timeout()), this, SLOT(timerFired())); // Connect "timerFired" method class to the "timeout" signal fired by the timer. this->timer->start(500); // Timer to fire every 500 milliseconds. } /* SLOT method for handling clicks on the "pause" button. Receives "clicked" signals on the "pause" button and stops the game simulation. */ void GridWindow::handlePause() { if(isRunning) // If it is running... this->timer->stop(); // Stops the timer. isRunning = false; // Set to false. } void GridWindow::handleForward() { if(isRunning); // If it's running, do nothing. else timerFired(); // It not running, step forward one step. } void GridWindow::handleBack() { std::vector<std::vector<GridCell*> > cells2; if(isRunning); // If it's running, do nothing. else if(backStack.empty()) cout << "EMPTYYY" << endl; else { cells2 = backStack.peek(); for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } cout << "PRE=POP" << endl; backStack.pop(); cout << "OYYYY" << endl; } } // Accessor method - Gets the 2D vector of grid cells. std::vector<std::vector<GridCell*> >& GridWindow::getCells() { return this->cells; } /* TimerFired function: 1) 2D-Vector cells2 is declared. 2) cells2 is initliazed with loops/push_backs so that all its cells are DEAD. 3) We loop through cells, and count the number of LIVE neighbors next to a given cell. --> Depending on how many cells are living, we choose if the cell should be LIVE or DEAD in the next simulation, according to the rules. -----> We save the cell type in cell2 at the same indice (the same row and column cell in cells2). 4) After check all the cells (and save the next round values in cells 2), we set cells's gridcells equal to cells2 gridcells. --> This causes the cells to be redrawn with cells2 types (white or black). */ void GridWindow::timerFired() { backStack.push(cells); std::vector<std::vector<GridCell*> > cells2; // Holds new values for 2D vector. These are the next simulation round of cell types. for(unsigned int i = 0; i < cells.size(); i++) // Loop through the rows of cells2. (Same size as cells' rows.) { vector<GridCell*> row; // Creates Gridcell* vector to push_back into cells2. cells2.push_back(row); // Pushes back row vectors into cells2. for(unsigned int j = 0; j < cells[i].size(); j++) // Loop through the columns (the cells in each row). { GridCell *cell = new GridCell(); // Creates new GridCell. cell->setType(DEAD); // Sets cell type to DEAD/white. cells2.at(i).push_back(cell); // Pushes back the DEAD cell into cells2. } // This makes a gridwindow the same size as cells with all DEAD cells. } for (unsigned int m = 0; m < cells.size(); m++) // Loop through cells' rows. { for (unsigned int n = 0; n < cells.at(m).size(); n++) // Loop through cells' columns. { unsigned int neighbors = 0; // Counter for number of LIVE neighbors for a given cell. // We know check all different variations of cells[i][j] to count the number of living neighbors for each cell. // We check m > 0 and/or n > 0 to make sure we don't access negative indexes (ex: cells[-1][0].) // We check m < size to make sure we don't try to access rows out of the vector (ex: row 5, if only 4 rows). // We check n < row size to make sure we don't access column item out of the vector (ex: 10th item in a column of only 9 items). // If we find that the Type = 1 (it is LIVE), then we add 1 to the neighbor. // Else - we add nothing to the neighbor counter. // Neighbor is the number of LIVE cells next to the current cell. if(m > 0 && n > 0) { if (cells[m-1][n-1]->getType() == 1) neighbors += 1; } if(m > 0) { if (cells[m-1][n]->getType() == 1) neighbors += 1; if(n < (cells.at(m).size() - 1)) { if (cells[m-1][n+1]->getType() == 1) neighbors += 1; } } if(n > 0) { if (cells[m][n-1]->getType() == 1) neighbors += 1; if(m < (cells.size() - 1)) { if (cells[m+1][n-1]->getType() == 1) neighbors += 1; } } if(n < (cells.at(m).size() - 1)) { if (cells[m][n+1]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1)) { if (cells[m+1][n]->getType() == 1) neighbors += 1; } if(m < (cells.size() - 1) && n < (cells.at(m).size() - 1)) { if (cells[m+1][n+1]->getType() == 1) neighbors += 1; } // Done checking number of neighbors for cells[m][n] // Now we change cells2 if it should switch in the next simulation step. // cells2 holds the values of what cells should be on the next iteration of the game. // We can't change cells right now, or it would through off our other cell values. // Apply game rules to cells: Create new, updated grid with the roundtwo vector. // Note - LIVE is 1; DEAD is 0. if (cells[m][n]->getType() == 1 && neighbors < 2) // If cell is LIVE and has less than 2 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && neighbors > 3) // If cell is LIVE and has more than 3 LIVE neighbors -> Set to DEAD. cells2[m][n]->setType(DEAD); else if (cells[m][n]->getType() == 1 && (neighbors == 2 || neighbors == 3)) // If cell is LIVE and has 2 or 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); else if (cells[m][n]->getType() == 0 && neighbors == 3) // If cell is DEAD and has 3 LIVE neighbors -> Set to LIVE. cells2[m][n]->setType(LIVE); } } // Now we've gone through all of cells, and saved the new values in cells2. // Now we loop through cells and set all the cells' types to those of cells2. for (unsigned int f = 0; f < cells.size(); f++) // Loop through cells' rows. { for (unsigned int g = 0; g < cells.at(f).size(); g++) // Loop through cells columns. { cells[f][g]->setType(cells2[f][g]->getType()); // Set cells[f][g]'s type to cells2[f][g]'s type. } } } stack.h - Here's my stack. #ifndef STACK_H_ #define STACK_H_ #include <iostream> #include "node.h" template <typename T> class Stack { private: Node<T>* top; int listSize; public: Stack(); int size() const; bool empty() const; void push(const T& value); void pop(); T& peek() const; }; template <typename T> Stack<T>::Stack() : top(NULL) { listSize = 0; } template <typename T> int Stack<T>::size() const { return listSize; } template <typename T> bool Stack<T>::empty() const { if(listSize == 0) return true; else return false; } template <typename T> void Stack<T>::push(const T& value) { Node<T>* newOne = new Node<T>(value); newOne->next = top; top = newOne; listSize++; } template <typename T> void Stack<T>::pop() { Node<T>* oldT = top; top = top->next; delete oldT; listSize--; } template <typename T> T& Stack<T>::peek() const { return top->data; // Returns data in top item. } #endif gridcell.cpp - Gridcell implementation #include <iostream> #include "gridcell.h" using namespace std; // Constructor: Creates a grid cell. GridCell::GridCell(QWidget *parent) : QFrame(parent) { this->type = DEAD; // Default: Cell is DEAD (white). setFrameStyle(QFrame::Box); // Set the frame style. This is what gives each box its black border. this->button = new QPushButton(this); //Creates button that fills entirety of each grid cell. this->button->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); // Expands button to fill space. this->button->setMinimumSize(19,19); //width,height // Min height and width of button. QHBoxLayout *layout = new QHBoxLayout(); //Creates a simple layout to hold our button and add the button to it. layout->addWidget(this->button); setLayout(layout); layout->setStretchFactor(this->button,1); // Lets the buttons expand all the way to the edges of the current frame with no space leftover layout->setContentsMargins(0,0,0,0); layout->setSpacing(0); connect(this->button,SIGNAL(clicked()),this,SLOT(handleClick())); // Connects clicked signal with handleClick slot. redrawCell(); // Calls function to redraw (set new type for) the cell. } // Basic destructor. GridCell::~GridCell() { delete this->button; } // Accessor for the cell type. CellType GridCell::getType() const { return(this->type); } // Mutator for the cell type. Also has the side effect of causing the cell to be redrawn on the GUI. void GridCell::setType(CellType type) { this->type = type; redrawCell(); // Sets type and redraws cell. } // Handler slot for button clicks. This method is called whenever the user clicks on this cell in the grid. void GridCell::handleClick() { // When clicked on... if(this->type == DEAD) // If type is DEAD (white), change to LIVE (black). type = LIVE; else type = DEAD; // If type is LIVE (black), change to DEAD (white). setType(type); // Sets new type (color). setType Calls redrawCell() to recolor. } // Method to check cell type and return the color of that type. Qt::GlobalColor GridCell::getColorForCellType() { switch(this->type) { default: case DEAD: return Qt::white; case LIVE: return Qt::black; } } // Helper method. Forces current cell to be redrawn on the GUI. Called whenever the setType method is invoked. void GridCell::redrawCell() { Qt::GlobalColor gc = getColorForCellType(); //Find out what color this cell should be. this->button->setPalette(QPalette(gc,gc)); //Force the button in the cell to be the proper color. this->button->setAutoFillBackground(true); this->button->setFlat(true); //Force QT to NOT draw the borders on the button } Thanks a lot. Let me know if you need anything else.

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• Segmentation fault in std function std::_Rb_tree_rebalance_for_erase ()

  - by Sarah

  I'm somewhat new to programming and am unsure how to deal with a segmentation fault that appears to be coming from a std function. I hope I'm doing something stupid (i.e., misusing a container), because I have no idea how to fix it. The precise error is Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x000000000000000c 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () (gdb) backtrace #0 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () #1 0x000000010000e593 in Simulation::runEpidSim (this=0x7fff5fbfcb20) at stl_tree.h:1263 #2 0x0000000100016078 in main () at main.cpp:43 The function that exits successfully just before the segmentation fault updates the contents of two containers. One is a boost::unordered_multimap called carriage; it contains one or more struct Infection objects that contain two doubles. The other container is of type std::multiset< Event, std::less< Event EventPQ called ce. It is full of Event structs. void Host::recover( int s, double recoverTime, EventPQ & ce ) { // Clearing all serotypes in carriage // and their associated recovery events in ce // and then updating susceptibility to each serotype double oldRecTime; int z; for ( InfectionMap::iterator itr = carriage.begin(); itr != carriage.end(); itr++ ) { z = itr->first; oldRecTime = (itr->second).recT; EventPQ::iterator epqItr = ce.find( Event(oldRecTime) ); assert( epqItr != ce.end() ); ce.erase( epqItr ); immune[ z ]++; } carriage.clear(); calcSusc(); // a function that edits an array cout << "Done with sync_recovery event." << endl; } The last cout << line appears immediately before the seg fault. I hope this is enough (but not too much) information. My idea so far is that the rebalancing is being attempting on ce after this function, but I am unsure why it would be failing. (It's unfortunately very hard for me to test this code by removing particular lines, since they would create logical inconsistencies and further problems, but if experienced programmers still think this is the way to go, I'll try.)

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• right usage of std::uncaught_exception in a destructor

  - by Vokuhila-Oliba

  There are some articles concluding "never throw an exception from a destructor", and "std::uncaught_exception() is not useful", for example: http://www.gotw.ca/gotw/047.htm (written by Herb Sutter) But it seems that I am not getting the point. So I wrote a small testing example (see below). Since everything is fine with the testing example I would very appreciate some comments regarding what might be wrong with it. testing results: ./main Foo::~Foo(): caught exception - but have pending exception - ignoring int main(int, char**): caught exception: from int Foo::bar(int) ./main 1 Foo::~Foo(): caught exception - but *no* exception is pending - rethrowing int main(int, char**): caught exception: from Foo::~Foo() // file main.cpp // build with e.g. "make main" // tested successfully on Ubuntu-Karmic with g++ v4.4.1 #include <iostream> class Foo { public: int bar(int i) { if (0 == i) throw(std::string("from ") + __PRETTY_FUNCTION__); else return i+1; } ~Foo() { bool exc_pending=std::uncaught_exception(); try { bar(0); } catch (const std::string &e) { // ensure that no new exception has been created in the meantime if (std::uncaught_exception()) exc_pending = true; if (exc_pending) { std::cerr << __PRETTY_FUNCTION__ << ": caught exception - but have pending exception - ignoring" << std::endl; } else { std::cerr << __PRETTY_FUNCTION__ << ": caught exception - but *no* exception is pending - rethrowing" << std::endl; throw(std::string("from ") + __PRETTY_FUNCTION__); } } } }; int main(int argc, char** argv) { try { Foo f; // will throw an exception in Foo::bar() if no arguments given. Otherwise // an exception from Foo::~Foo() is thrown. f.bar(argc-1); } catch (const std::string &e) { std::cerr << __PRETTY_FUNCTION__ << ": caught exception: " << e << std::endl; } return 0; }

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• pointers to functions

  - by DevAno1

  I have two basic Cpp tasks, but still I have problems with them. First is to write functions mul1,div1,sub1,sum1, taking ints as arguments and returning ints. Then I need to create pointers ptrFun1 and ptrFun2 to functions mul1 and sum1, and print results of using them. Problem starts with defining those pointers. I thought I was doing it right, but devcpp gives me errors in compilation. #include <iostream> using namespace std; int mul1(int a,int b) { return a * b; } int div1(int a,int b) { return a / b; } int sum1(int a,int b) { return a + b; } int sub1(int a,int b) { return a - b; } int main() { int a=1; int b=5; cout << mul1(a,b) << endl; cout << div1(a,b) << endl; cout << sum1(a,b) << endl; cout << sub1(a,b) << endl; int *funPtr1(int, int); int *funPtr2(int, int); funPtr1 = sum1; funPtr2 = mul1; cout << funPtr1(a,b) << endl; cout << funPtr2(a,b) << endl; system("PAUSE"); return 0; } 38 assignment of function int* funPtr1(int, int)' 38 cannot convertint ()(int, int)' to `int*()(int, int)' in assignment Task 2 is to create array of pointers to those functions named tabFunPtr. How to do that ?

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• chrooting user causes "connection closed" message when using sftp

  - by George Reith

  First off I am a linux newbie so please don't assume much knowledge. I am using CentOS 5.8 (final) and using OpenSSH version 5.8p1. I have made a user playwithbits and I am attempting to chroot them to the directory home/nginx/domains/playwithbits/public I am using the following match statement in my sshd_config file: Match group web-root-locked ChrootDirectory /home/nginx/domains/%u/public X11Forwarding no AllowTcpForwarding no ForceCommand /usr/libexec/openssh/sftp-server # id playwithbits returns: uid=504(playwithbits) gid=504(playwithbits) groups=504(playwithbits),507(web-root-locked) I have changed the user's home directory to: home/nginx/domains/playwithbits/public Now when I attempt to sftp in with this user I instantly get the message: connection closed Does anyone know what I am doing wrong? Edit: Following advice from @Dennis Williamson I have connected in debug mode (I think... correct me if I'm wrong). I have made a bit of progress by using chmod to set permissions recursively of all files in the directly to 700. Now I get the following messages when I attempt to log on (still connection refused): Connection from [My ip address] port 38737 debug1: Client protocol version 2.0; client software version OpenSSH_5.6 debug1: match: OpenSSH_5.6 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8 debug1: permanently_set_uid: 74/74 debug1: list_hostkey_types: ssh-rsa,ssh-dss debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: client->server aes128-ctr hmac-md5 none debug1: kex: server->client aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: KEX done debug1: userauth-request for user playwithbits service ssh-connection method none debug1: attempt 0 failures 0 debug1: user playwithbits matched group list web-root-locked at line 91 debug1: PAM: initializing for "playwithbits" debug1: PAM: setting PAM_RHOST to [My host info] debug1: PAM: setting PAM_TTY to "ssh" debug1: userauth-request for user playwithbits service ssh-connection method password debug1: attempt 1 failures 0 debug1: PAM: password authentication accepted for playwithbits debug1: do_pam_account: called Accepted password for playwithbits from [My ip address] port 38737 ssh2 debug1: monitor_child_preauth: playwithbits has been authenticated by privileged process debug1: SELinux support disabled debug1: PAM: establishing credentials User child is on pid 3942 debug1: PAM: establishing credentials Changed root directory to "/home/nginx/domains/playwithbits/public" debug1: permanently_set_uid: 504/504 debug1: Entering interactive session for SSH2. debug1: server_init_dispatch_20 debug1: server_input_channel_open: ctype session rchan 0 win 2097152 max 32768 debug1: input_session_request debug1: channel 0: new [server-session] debug1: session_new: session 0 debug1: session_open: channel 0 debug1: session_open: session 0: link with channel 0 debug1: server_input_channel_open: confirm session debug1: server_input_global_request: rtype [email protected] want_reply 0 debug1: server_input_channel_req: channel 0 request env reply 0 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req env debug1: server_input_channel_req: channel 0 request subsystem reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req subsystem subsystem request for sftp by user playwithbits debug1: subsystem: cannot stat /usr/libexec/openssh/sftp-server: Permission denied debug1: subsystem: exec() /usr/libexec/openssh/sftp-server debug1: Forced command (config) '/usr/libexec/openssh/sftp-server' debug1: session_new: session 0 debug1: Received SIGCHLD. debug1: session_by_pid: pid 3943 debug1: session_exit_message: session 0 channel 0 pid 3943 debug1: session_exit_message: release channel 0 debug1: session_by_channel: session 0 channel 0 debug1: session_close_by_channel: channel 0 child 0 debug1: session_close: session 0 pid 0 debug1: channel 0: free: server-session, nchannels 1 Received disconnect from [My ip address]: 11: disconnected by user debug1: do_cleanup debug1: do_cleanup debug1: PAM: cleanup debug1: PAM: closing session debug1: PAM: deleting credentials

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• Boggling Direct3D9 dynamic vertex buffer Lock crash/post-lock failure on Intel GMA X3100.

  - by nj

  Hi, For starters I'm a fairly seasoned graphics programmer but as wel all know, everyone makes mistakes. Unfortunately the codebase is a bit too large to start throwing sensible snippets here and re-creating the whole situation in an isolated CPP/codebase is too tall an order -- for which I am sorry, do not have the time. I'll do my best to explain. B.t.w, I will of course supply specific pieces of code if someone wonders how I'm handling this-or-that! As with all resources in the D3DPOOL_DEFAULT pool, when the device context is taken away from you you'll sooner or later will have to reset your resources. I've built a mechanism to handle this for all relevant resources that's been working for years; but that fact nothingwithstanding I've of course checked, asserted and doubted any assumption since this bug came to light. What happens is as follows: I have a rather large dynamic vertex buffer, exact size 18874368 bytes. This buffer is locked (and discarded fully using the D3DLOCK_DISCARD flag) each frame prior to generating dynamic geometry (isosurface-related, f.y.i) to it. This works fine, until, of course, I start to reset. It might take 1 time, it might take 2 or it might take 5 resets to set off a bug that causes an access violation either on the pointer returned by the Lock() operation on the renewed resource or a plain crash -- regarding a somewhat similar address, but without the offset that it has tacked on to it in the first case because in that case we're somewhere halfway writing -- iside the D3D9 dll Lock() call. I've tested this on other hardware, upgraded my GMA X3100 drivers (using a MacBook with BootCamp) to the latest ones, but I can't reproduce it on any other machine and I'm at a loss about what's wrong here. I have tried to reproduce a similar situation with a similar buffer (I've got a large scratch pad of the same type I filled with quads) and beyond a certain amount of bytes it started to behave likewise. I'm not asking for a solution here but I'm very interested if there are other developers here who have battled with the same foe or maybe some who can point me in some insightful direction, maybe ask some questions that might shed a light on what I may or may not be overlooking. Another interesting artifact is that the vertex buffer starts to bug if I supply both D3DLOCK_DISCARD and D3DLOCK_NOOVERWRITE together which, even though not very logical (you're not going to overwrite if you've just discarded all), gives graphics glitches. Thanks and any corrections are more than welcome. Niels p.s - A friend of mine raised the valid point that it is a huge buffer for onboard video RAM and it's being at least double or triple buffered internally due to it's dynamic nature. On the other hand, the debug output (D3D9 debug DLL + max. warning output) remains silent. p.s 2 - Had it tested on more machines and still works -- it's probably a matter of circumstance: the huge dynamic, internally double/trippled buffered buffer, not a lot of memory and drivers that don't complain when they should.. Unless someone has a better suggestion; I'd still love to hear it :)

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• When is #include <new> library required in C++?

  - by Czarak

  Hi, According to this reference entry for operator new ( http://www.cplusplus.com/reference/std/new/operator%20new/ ) : Global dynamic storage operator functions are special in the standard library: All three versions of operator new are declared in the global namespace, not in the std namespace. The first and second versions are implicitly declared in every translation unit of a C++ program: The header does not need to be included for them to be present. This seems to me to imply that the third version of operator new (placement new) is not implicitly declared in every translation unit of a C++ program and the header <new> does need to be included for it to be present. Is that correct? If so, how is it that using both g++ and MS VC++ Express compilers it seems I can compile code using the third version of new without #include <new> in my source code? Also, the MSDN Standard C++ Library reference entry on operator new gives some example code for the three forms of operator new which contains the #include <new> statement, however the example seems to compile and run just the same for me without this include? // new_op_new.cpp // compile with: /EHsc #include<new> #include<iostream> using namespace std; class MyClass { public: MyClass( ) { cout << "Construction MyClass." << this << endl; }; ~MyClass( ) { imember = 0; cout << "Destructing MyClass." << this << endl; }; int imember; }; int main( ) { // The first form of new delete MyClass* fPtr = new MyClass; delete fPtr; // The second form of new delete char x[sizeof( MyClass )]; MyClass* fPtr2 = new( &x[0] ) MyClass; fPtr2 -> ~MyClass(); cout << "The address of x[0] is : " << ( void* )&x[0] << endl; // The third form of new delete MyClass* fPtr3 = new( nothrow ) MyClass; delete fPtr3; } Could anyone shed some light on this and when and why you might need to #include <new> - maybe some example code that will not compile without #include <new> ? Thanks.

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• GCC: Simple inheritance test fails

  - by knight666

  I'm building an open source 2D game engine called YoghurtGum. Right now I'm working on the Android port, using the NDK provided by Google. I was going mad because of the errors I was getting in my application, so I made a simple test program: class Base { public: Base() { } virtual ~Base() { } }; // class Base class Vehicle : virtual public Base { public: Vehicle() : Base() { } ~Vehicle() { } }; // class Vehicle class Car : public Vehicle { public: Car() : Base(), Vehicle() { } ~Car() { } }; // class Car int main(int a_Data, char** argv) { Car* stupid = new Car(); return 0; } Seems easy enough, right? Here's how I compile it, which is the same way I compile the rest of my code: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-g++ -g -std=c99 -Wall -Werror -O2 -w -shared -fshort-enums -I ../../YoghurtGum/src/GLES -I ../../YoghurtGum/src -I /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/include -c src/Inheritance.cpp -o intermediate/Inheritance.o (Line breaks are added for clarity). This compiles fine. But then we get to the linker: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-gcc -lstdc++ -Wl, --entry=main, -rpath-link=/system/lib, -rpath-link=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -dynamic-linker=/system/bin/linker, -L/home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/lib/gcc/arm-eabi/4.4.0, -L/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -rpath=../../YoghurtGum/lib/GLES -nostdlib -lm -lc -lGLESv1_CM -z /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtbegin_dynamic.o /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtend_android.o intermediate/Inheritance.o ../../YoghurtGum/bin/YoghurtGum.a -o bin/Galaxians.android As you can probably tell, there's a lot of cruft in there that isn't really needed. That's because it doesn't work. It fails with the following errors: intermediate/Inheritance.o:(.rodata._ZTI3Car[typeinfo for Car]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI7Vehicle[typeinfo for Vehicle]+0x0): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI4Base[typeinfo for Base]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1 These are the same errors I get from my actual application. If someone could explain to me where I went wrong in my test or what option or I forgot in my linker, I would be very, extremely grateful. Thanks in advance. UPDATE: When I make my destructors non-inlined, I get new and more exciting link errors: intermediate/Inheritance.o:(.rodata+0x78): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata+0x90): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata+0xb0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1

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• cannot retrieve effect.fx file

  - by numerical25

  I am having issues loading my effect.fx from directx. When I step into my application, my ID3D10Effect *m_pDefaultEffect; pointer remains empty. the address remains at 0x000000 below is my code #pragma once #include "stdafx.h" #include "resource.h" #include "d3d10.h" #include "d3dx10.h" #include "dinput.h" #define MAX_LOADSTRING 100 class RenderEngine { protected: RECT m_screenRect; //direct3d Members ID3D10Device *m_pDevice; // The IDirect3DDevice10 // interface ID3D10Texture2D *m_pBackBuffer; // Pointer to the back buffer ID3D10RenderTargetView *m_pRenderTargetView; // Pointer to render target view IDXGISwapChain *m_pSwapChain; // Pointer to the swap chain RECT m_rcScreenRect; // The dimensions of the screen ID3D10Texture2D *m_pDepthStencilBuffer; ID3D10DepthStencilState *m_pDepthStencilState; ID3D10DepthStencilView *m_pDepthStencilView; //transformation matrixs D3DXMATRIX g_mtxWorld; D3DXMATRIX g_mtxView; D3DXMATRIX g_mtxProj; //Effect members ID3D10Effect *m_pDefaultEffect; ID3D10EffectTechnique *m_pDefaultTechnique; ID3DX10Font *m_pFont; // The font used for rendering text // Sprites used to hold font characters ID3DX10Sprite *m_pFontSprite; ATOM RegisterEngineClass(); void DoFrame(float); bool LoadEffects(); public: static HINSTANCE m_hInst; HWND m_hWnd; int m_nCmdShow; TCHAR m_szTitle[MAX_LOADSTRING]; // The title bar text TCHAR m_szWindowClass[MAX_LOADSTRING]; // the main window class name void DrawTextString(int x, int y, D3DXCOLOR color, const TCHAR *strOutput); //static functions static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam); static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam); bool InitWindow(); bool InitDirectX(); bool InitInstance(); int Run(); void ShutDown(); RenderEngine() { m_screenRect.right = 800; m_screenRect.bottom = 600; } }; below is the implementation bool RenderEngine::LoadEffects() { HRESULT hr; ID3D10Blob *pErrors = 0; // Create the default rendering effect hr = D3DX10CreateEffectFromFile(L"effect.fx", NULL, NULL, "fx_4_0", D3D10_SHADER_DEBUG, 0, m_pDevice, NULL, NULL, &m_pDefaultEffect, &pErrors, NULL); if(pErrors)// at this point, m_pDefaultEffect is still empty but pErrors returns data which means there is {//errors return false; //ends here } //m_pDefaultTechnique = m_pDefaultEffect->GetTechniqueByName("DefaultTechnique"); return true; } My directx Device does work. My effect.fx file is in the same folder as my solution files (.cpp and header files)

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