I am developing programs for VxWorks using Tornado 2.2. I meet some problem when I try to use cout. My code is here:
#include <iostream>
using namespace std;
void main()
{
cout << "Hi" << endl;
}
The project can be compiled without error. But when I try to download the .out file to the target machine (mounted on VMware), I got the following error:
What's the problem and how to solve it?
The problem is you are missing the appropriate library in the kernel configuration. To rectify this, you will need to add the correct component to the kernel configuration.
At the least, you will need to add INCLUDE_CPLUS_IOSTREAMS, however this might also require other components, possibly one or more of INCLUDE_CPLUS, INCLUDE_CPLUS_DEMANGLER or INCLUDE_CPLUS_LANG, dependant on what is already included.
If you are using the tornado GUI to configure your kernel, you can just browse through the tree - I can't remember the exact location in Tornado, but is fairly near the top - probably under C++ Components.
If you are using the command line to make your project, you may need to edit config.h directly.
That's some old tech you got there... Check you kernel configuration for various CPLUS options - you're missing something.
Related
I am trying to find the position of an image in another image using SURF, but every time I try to initialize the detector, it fails, telling me that there was an access violation and that detector.Ptr was "0xFFFFFFFFFFFFFF".
My code:
auto detector = cv::xfeatures2d::SurfFeatureDetector::create();
detector->detect(map,keypointsMap);
detector->detectAndCompute(compare, noArray(), keypointsCompare, descriptorComp);
This happens even when i use the example code from the opencv documentation (https://docs.opencv.org/3.4/d7/dff/tutorial_feature_homography.html). I can use the other non-free features like SIFT without any problems.
I am using opencv4 and I am including the following libraries:
#include "opencv2/core.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/features2d.hpp"
#include "opencv2/xfeatures2d.hpp"
#include "opencv2/xfeatures2d/nonfree.hpp"
#include "opencv2/imgproc.hpp"
Has anybody seen this issue before and maybe knows a solution?
Thank you
I have found the problem, when I reinstalled opencv on my laptop. It seems that you have to configure cmake the right way (specify path for modules and allow nonfree) when you build opencv the first try to get SURF and SIFT to work. If you don't, you can't fix it by overwriting the old files. SIFT will work then, but not SURF, for some reason. So I deleted everything on my PC and then did the configuration right from the start and now it works. Oh, and also make sure you add everything to the path correctly.
Extremely useful description to install opencv on windows 10: https://www.youtube.com/watch?v=x5EWlNQ6z5w
Thank you Grillteller and everyone who read this!
I want to build C++ desktop applications using visual studio and wxWidgets on windows 7. I'm coming from C++ Builder.
I downloaded and built the wxWidgets libraries successfully and I can run the minimal_vc14 solution just fine. Now it comes time to create my Hello World app. I've created a new, empty C++ project and using NuGet added the wxWidgets template. Then I use class wizard to add a new class (Test3) with a base class of wxApp.
I immediately get 45 errors. The first of which is
Severity Code Description Project File Line Suppression State
Error (active) cannot open source file "../../../lib/vc_dll/mswud/wx/setup.h" Test3 c:\wxWidgets-3.1.0\include\msvc\wx\setup.h 121
digging into that file I find the following bit. The last include statement is the problem line identified above, but the problem I think is in the wxConcat6 statement. All of those ../ lead nowhere. Shouldn't that point to $(WXWIN)?
// the real setup.h header file we need is in the build-specific directory,
// construct the path to it
#ifdef wxSUFFIX
#define wxSETUPH_PATH \
wxCONCAT6(../../../lib/, wxLIB_SUBDIR, /, wxTOOLKIT_PREFIX, wxSUFFIX, /wx/setup.h)
#else // suffix is empty
#define wxSETUPH_PATH \
wxCONCAT5(../../../lib/, wxLIB_SUBDIR, /, wxTOOLKIT_PREFIX, /wx/setup.h)
#endif
#define wxSETUPH_PATH_STR wxSTRINGIZE(wxSETUPH_PATH)
#include wxSETUPH_PATH_STR
Also, smaller problem but further up the setup.h file I see that WXUSINGDLL has been defined, but I want to use libs. I can't figure out where that is being set either.
Obviously there is a configuration step I missed somewhere. Please advise.
As usual the answer can be found by reading EVERYTHING.
There are 2 things that need to be configured for this process to work correctly.
After creating the project go to the project properties and set the character set to Unicode. The default is Multi-Byte. My next quest will be to find where to change the default!
After installing the package template (or is it a template package?) go to the project properties and set shared to "statically linked build".
Presto changeo, you are ready to go. Add the following for the absolute minimum to make a compilable application. This is based on the tutorial here:creating-wxwidgets-programs-with-visual-studio-2015
bool MyProjectApp::OnInit()
{
wxFrame* mainFrame = new wxFrame(nullptr, wxID_ANY, L"MyProject");
mainFrame->Show(true);
return true;
}
wxIMPLEMENT_APP(MyProjectApp);
I suggest you make a copy of minimal sample (or widgets, as it uses more controls and links more libs), in the same location, and modify the source file as you need.
When you have played enough with it, for sure you'll find it quite easy to change the project file so that it'll use $(WXWIN) or any other custom settings.
p.s. I don't know what "wxWidgets template" from NuGet contains, but I strongly doubt it is provided by wxWidgets maintainers.
I am giving Gwan a whirl.
Having made it through example code, I started a small project with more than one source file. I now have two problems:
I got a linking error at server startup:
Linking main.cpp: undefined symbol: _ZN7GwanUrl9concatAllEv
(the main file #includes the two other files; all the files are in the csp directory)
As an alternative to having all the files in the /csp directory, I would like to make a library outside of the /csp directory while still using some of the gwan functions. sadly, a tonne of errors follow -- WHEN I GCC from commandline not via G-WAN Startup.
In file included from /home/ec2-user/gwan/include/gwan.h:22,
from Xbufstream.h:10,
from Xbufstream.cpp:10:
/usr/include/time.h:199: error: ‘size_t’ does not name a type
.....
Anyone knows what the gwan g++ argument string looks like?
(odd the 1. and 1. its 1. and 2. in the editor)
First, this is not a linker issue: you have "undefined symbol" rather than "unresolved symbol" as an error.
This is simply an #include issue.
define the main() function in your script.cpp file.
there's a G-WAN folder dedicated to user-defined include files called /gwan/include but you can as well use /csp/my_include.hpp... if you are using the right syntax:
For example, having #include "toto.hpp" in /csp/hello.cpp lets me reach C++ functions defined and implemented in the gwan/include/toto.hpp file (or defined in toto.hpp and implemented in a pre-compiled library linked to your script with #pragma link).
If you rather use #include <toto.hpp> then the SYSTEM INCLUDE PATH will be searched instead (and this will work providing that your library was correctly installed).
If you want to use #include "toto.hpp" for a custom folder that was not setup in the system, you can use G-WAN's #pragma include "../my_folder" directive to specify its PATH or you can explicitely specify it in each include: #include "../my_folder/toto.hpp".
Nothing fancy there, only C/C++ dependancy rules apply (and G-WAN really helps by providing alternate ways that do not involve system settings).
For libraries (see the G-WAN examples for SQLite, Cairo, mySQL, cURL, etc.) you can either use pre-installed libraries that exported their location in SYSTEM variables... or put your library in the /gwan/libraries folder and their include file in the /gwan/include folder.
When writing your own libraries, remember that they need to be pre-compiled. This means that you obviously cannot use G-WAN symbols since your compiler may #include "gwan.h" (to have the definitions) but your linker will not know from where G-WAN symbols can be found. The way around is to always use the G-WAN API from the G-WAN scripts. Your custom libraries must either be general-purpose or buffer any payload intended to be used by G-WAN. No-double copy is needed since G-WAN provides the set_reply() call to let G-WAN use persistent replies built without the reply xbuffer provided by G-WAN servlets.
Now, a last word about linking (which was not the cause of your trouble but could participate to the confusion). If you mix C and C++, use extern C {} to wrap your C++ prototypes called from C (otherwise you will really have "unresolved symbols").
With all this information, you should be ready to face every possible situation.
the issue of referencing gwan.h symbols inside #include files can also be solved by moving all code into the header file, whether its .h or .hpp
its ungraceful but a fix nevertheless. and good enough for the simple extension i wanted.
looking into the /libraries/sqlite3/sqlite.h helped.
#gil, thanks for your time.
Can anyone please help me with getting the proper header files needed for the copy_from_user method?
I found a few of the include headers I need, but my compiler keeps saying that they are not found. I am running CentOS on my machine. I have tried yum installing various kernel-headers and devel packages but still no luck.
Is there a special segment I need to add in my gcc command? Everything I find on the Internet only tells me how to use the method but not actually how I can get access to it in the first place.
I assume you're developing a kernel module, because outside of it trying to use copy_from_user wouldn't make sense. Either way, in the kernel use:
#include <linux/uaccess.h>
Edit: if building a kernel module is what you want, you may want to look at this Hello World Linux Kernel Module. Specifically the makefile portion may be of interest to you (search for obj-m).
I've run into trouble in the past when I've tried porting some C++ code written on Mac OS X to a Linux system, or trying to compile code written against an older version of gcc/g++ with a newer one:
It seems that some (older?) versions of gcc/g++ would automatically include some header files for you.
For example, code that uses printf should require #include <stdio.h>. And code that uses memcpy should require #include <string.h>. But depending on the version of gcc I'm using, it will occasionally include these for me.
It wreaks havoc when I forget to include something and then never get errors until I go to compile the code on another system. At that point it's a game of running all over the project and fixing the includes.
Has anyone else run into this? Is there a way to force gcc to autoinclude or to not autoinclude? Or, is there a way to know what it's autoincluding?
-include file
Process file as if #include "file" appeared as the first line of the primary source file. However, the first directory searched for file is the preprocessor's working directory instead of the directory containing the main source file. If not found there, it is searched for in the remainder of the #include "..." search chain as normal.
If multiple -include options are given, the files are included in the order they appear on the command line.
http://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html
Are you sure it's not other headers pulling those one's in, and on the other platforms not doing so?
When compiling on different systems, you might meet different problems and not only includes.
I would suggest investing in a continuous build system that will compile on all OS you need after each update of the code, so you are rapidly aware of any portability issue.
You can also put all common system header files inside a specific header file you will write and systematically include it in all your files.