This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 7 years ago.
I am using OpenCV to record the video from webcam. I used Xcode 6.4 to write a (C++) code to record the video on OS X Yosemite 10.10.4. It is working perfectly fine when I compile and run it from Xcode but when I want to compile (using g++ -o main main.cpp) it from terminal it generates following errors:
Undefined symbols for architecture x86_64:
"cv::VideoWriter::write(cv::Mat const&)", referenced from:
_main in main-027833.o
"cv::VideoWriter::VideoWriter(cv::String const&, int, double, cv::Size_<int>, bool)", referenced from:
_main in main-027833.o
"cv::VideoWriter::~VideoWriter()", referenced from:
_main in main-027833.o
"cv::VideoCapture::VideoCapture(int)", referenced from:
_main in main-027833.o
"cv::VideoCapture::~VideoCapture()", referenced from:
_main in main-027833.o
"cv::VideoCapture::operator>>(cv::Mat&)", referenced from:
_main in main-027833.o
"cv::Mat::deallocate()", referenced from:
cv::Mat::release() in main-027833.o
"cv::String::deallocate()", referenced from:
cv::String::~String() in main-027833.o
"cv::String::allocate(unsigned long)", referenced from:
cv::String::String(char const*) in main-027833.o
"cv::imshow(cv::String const&, cv::_InputArray const&)", referenced from:
_main in main-027833.o
"cv::waitKey(int)", referenced from:
_main in main-027833.o
"cv::fastFree(void*)", referenced from:
cv::Mat::~Mat() in main-027833.o
"cv::VideoCapture::get(int) const", referenced from:
_main in main-027833.o
"cv::VideoCapture::isOpened() const", referenced from:
_main in main-027833.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command fail
ed with exit code 1 (use -v to see invocation)
I know its because it can't link OpenCV lib. I tried using "vi
$HOME/.bash_profile" and then setting path like
"export PATH=$PATH:/usr/local/include"
and
"export PATH=$PATH:/user/local/lib"
but it doesn't help. Also I tried
g++ -o main main.cpp -l `pkg-config opencv --cflags --libs`
but of no use.
I don't know how to specify path. Any help would be appreciated.
Thanks!
Finally, after 3 days of frustration I found the solution. I am sharing for someone who is also struggling with the same kind of problem.
What you have to do is just add all those flags that you added in the Xcode "other linker flags" while compiling your code from terminal. So here is the command that works for me.
g++ main.cpp -o main -I/usr/local/include -L/usr/local/lib -lopencv_core -lopencv_calib3d -lopencv_videoio -lopencv_video -lopencv_videostab -lopencv_highgui
I didn't include all the flags because I was only working with videos but you may have to add more or less depending on what you are working on.
Related
$clang++ main.cpp -o out
Got following error, the same error happens when changing to g++. I have tested on some simple simple c++ code, the command works fine. So it the problem in that PNG class file? However, the same files worked on my MacOS before, but suddenly failed today.
Undefined symbols for architecture x86_64:
"PNG::writeToFile(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
_main in main-f6a06a.o
"PNG::PNG(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
_main in main-f6a06a.o
"PNG::PNG(unsigned long, unsigned long)", referenced from:
_main in main-f6a06a.o
"PNG::~PNG()", referenced from:
_main in main-f6a06a.o
"PNG::operator()(unsigned long, unsigned long)", referenced from:
_main in main-f6a06a.o
"PNG::width() const", referenced from:
_main in main-f6a06a.o
"PNG::height() const", referenced from:
_main in main-f6a06a.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Did you miss providing static/shared to the linker to resolve the linker errors for the methods mentioned? Also note that clang++ is a different compiler compared to g++ and hence need the static/shared libraries compiled prior by the same compiler you are using (clang++).
Try:
clang++ main.cpp -o out -lpng
Here's why: You are not providing the library that contains the implementation of your PNG library (libpng most likely). You need -lpng added to your compiler, so that it links with the relevant library. It may not be exactly -lpng in your particular case, but it's definitely a "missing library". Without knowing exactly what library you are trying to use (you didn't provide some source to "try the fix with").
As pointed out in the comment: you are using some kind of C++ wrapper on top, the above is probably not enough - but without knowing exactly which C++ wrapper on the png functionality you are actually using, it's hard to say what the command-line should look like.
Perhaps this
I am new to cpp, want to have a implementation of particle filter, I try to run the code here https://github.com/NewProggie/Particle-Filter, which is a structured and easy understanding project. But when I try to compile and link:
g++ $(pkg-config --cflags --libs opencv) -I/usr/local/Cellar/opencv3/3.1.0_1/include -I /usr/local/Cellar/gsl/1.16/include -stdlib=libc++ main.cpp -o main
I have following linking problem:
Undefined symbols for architecture x86_64:
"colorFeatures::colorFeatures()", referenced from:
_main in main-2b4c23.o
"colorFeatures::~colorFeatures()", referenced from:
_main in main-2b4c23.o
"adaboostDetect::detectObject(_IplImage*, CvRect**)", referenced from:
_main in main-2b4c23.o
"adaboostDetect::adaboostDetect()", referenced from:
_main in main-2b4c23.o
"tracker::addObjects(_IplImage*, CvRect*, int)", referenced from:
_main in main-2b4c23.o
"tracker::initTracker(_IplImage*, CvRect*, int, int)", referenced from:
_main in main-2b4c23.o
"tracker::showResults(_IplImage*)", referenced from:
_main in main-2b4c23.o
"tracker::next(_IplImage*)", referenced from:
_main in main-2b4c23.o
"tracker::tracker()", referenced from:
_main in main-2b4c23.o
"tracker::~tracker()", referenced from:
_main in main-2b4c23.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Any kind person has ideas about this problem? Thanks in advance
have gsl installed properly
B) pass to g++ a reference to the lib directory where the gsl libraries are located (probably something like /usr/lib or /usr/local/lib, these should both be default locations for the linker to search), and also to where the header files are, and also tell the linker to do the linking.
g++ -o <name of executable> -L/path/to/gsl/libs -I/path/to/headers -lgsl <name of source file>
the -L tells it where to find the libraries (.so files on linux, .dylib on OS X), -I tells it where to find the headers, -l (that's a lower case L) tells it to link to the library, which would be named libgsl.so or libgsl.dylib.
First just try adding the -lgsl flag, then if it can't find libgsl.so (or .dylib), add the -L flag. NOTE: /path/to/gsl/libs and /path/to/headers are not what you should literally put in there, but replace them with the actual paths on your system.
I am testing out eclipse C++ for Mac. I have three specific questions.
This is the classic iostream problem for Mac. It does not know where to find it. So in the project properties I add the path where iostream is located (Preferences->C/C++ General->Paths and Symbols->includes). Now iostream works. But I am trying to find a way where I don't have to do this for every new project. Is there a specific setting I can select to include this directory automatically for each new project?
Is xCode necessary for eclipse to work? If yes, how can I get eclipse to work without it? xCode takes up 6 GBs.
I'm getting an error on a test project (see below) that I'm not sure how to fix. Something about "linker command failed". I seem to be able to compile regular C programs fine though. Note this project works fine in Visual Studio.
23:37:30 **** Incremental Build of configuration Debug for project pointClass ****
make all
Building target: pointClass
Invoking: MacOS X C++ Linker
g++ -o "pointClass" ./point.o ./test.o
Undefined symbols for architecture x86_64:
"std::istream::operator>>(double&)", referenced from:
_main in test.o
"std::ostream::operator<<(std::ostream& ()(std::ostream&))", referenced from:
_main in test.o
Point::Point(double, double) in test.o
Point::Point(Point const&) in test.o
"std::ostream::operator<<(double)", referenced from:
_main in test.o
Point::Point(double, double) in test.o
"std::basic_string, std::allocator >::~basic_string()", referenced from:
_main in test.o
"std::ios_base::Init::Init()", referenced from:
___cxx_global_var_init in test.o
"std::ios_base::Init::~Init()", referenced from:
___cxx_global_var_init in test.o
"std::cin", referenced from:
_main in test.o
"std::cout", referenced from:
_main in test.o
Point::Point(double, double) in test.o
Point::Point(Point const&) in test.o
"std::basic_ostream >& std::endl >(std::basic_ostream >&)", referenced from:
_main in test.o
Point::Point(double, double) in test.o
Point::Point(Point const&) in test.o
"std::basic_ostream >& std::operator<< >(std::basic_ostream >&, char const)", referenced from:
_main in test.o
Point::Point(double, double) in test.o
Point::Point(Point const&) in test.o
"std::basic_ostream >& std::operator<<, std::allocator >(std::basic_ostream >&, std::basic_string, std::allocator > const&)", referenced from:
_main in test.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [pointClass] Error 1
I am trying to run an opencv project by xcode6.
This tutorial is cool and works for me, first, without xcode: The application runs perfectly after make'ing.
Now, I want to use Xcode 6 as development environment.
But I get an Apple Mach-O Linker error.
Build Settings are:
Header Search Paths : /usr/local/include (non-recursive)
Library Search Paths: /urs/local/lib (non-recursive)
Build Phases > Link Binary With Libraries:
Libc++.dylib
This is the error:
Ld /Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Products/Debug/HelloWorld normal x86_64
cd /Users/XXX/Desktop/make/CLTproject/HelloWorld/HelloWorld
export MACOSX_DEPLOYMENT_TARGET=10.10
/Applications/Xcode-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch x86_64 -isysroot /Applications/Xcode-Beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -L/Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Products/Debug -L/usr/local/lib -F/Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Products/Debug -filelist /Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Intermediates/HelloWorld.build/Debug/HelloWorld.build/Objects-normal/x86_64/HelloWorld.LinkFileList -mmacosx-version-min=10.10 -stdlib=libc++ -lc++ -Xlinker -dependency_info -Xlinker /Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Intermediates/HelloWorld.build/Debug/HelloWorld.build/Objects-normal/x86_64/HelloWorld_dependency_info.dat -o /Users/XXX/Library/Developer/Xcode/DerivedData/HelloWorld-ejnkjggujedpyibjbhvocitoxxaj/Build/Products/Debug/HelloWorld
Undefined symbols for architecture x86_64:
"cv::namedWindow(cv::String const&, int)", referenced from:
_main in main.o
"cv::GaussianBlur(cv::_InputArray const&, cv::_OutputArray const&, cv::Size_<int>, double, double, int)", referenced from:
_main in main.o
"cv::Mat::deallocate()", referenced from:
cv::Mat::release() in main.o
"cv::Mat::copySize(cv::Mat const&)", referenced from:
cv::Mat::operator=(cv::Mat const&) in main.o
"cv::String::deallocate()", referenced from:
cv::String::~String() in main.o
"cv::String::allocate(unsigned long)", referenced from:
cv::String::String(char const*) in main.o
"cv::imread(cv::String const&, int)", referenced from:
_main in main.o
"cv::imshow(cv::String const&, cv::_InputArray const&)", referenced from:
_main in main.o
"cv::waitKey(int)", referenced from:
_main in main.o
"cv::fastFree(void*)", referenced from:
cv::Mat::~Mat() in main.o
"cv::Mat::copyTo(cv::_OutputArray const&) const", referenced from:
cv::Mat::clone() const in main.o
"vtable for cv::_InputArray", referenced from:
cv::_InputArray::_InputArray() in main.o
cv::_InputArray::_InputArray(cv::Mat const&) in main.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
"vtable for cv::_OutputArray", referenced from:
cv::_OutputArray::_OutputArray(cv::Mat&) in main.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Any Idea?
Thanks,
isicom
Just to give some light to everybody in the same problem. I added all libraries and worked fine for me. I stayed in the libc++ with no building errors.
I'm trying to use Poco C++ library to do the simple http requests in C++ on Mac OS X 10.8.2. I installed Poco, copy-pasted the http_request.cc code from this tutorial, ran it with 'g++ -o http_get http_get.cc -lPocoNet', but got:
Undefined symbols for architecture x86_64:
"Poco::StreamCopier::copyStream(std::basic_istream<char, std::char_traits<char> >&, std::basic_ostream<char, std::char_traits<char> >&, unsigned long)", referenced from:
_main in ccKuZb1g.o
"Poco::URI::URI(char const*)", referenced from:
_main in ccKuZb1g.o
"Poco::URI::~URI()", referenced from:
_main in ccKuZb1g.o
"Poco::URI::getPathAndQuery() const", referenced from:
_main in ccKuZb1g.o
"Poco::URI::getPort() const", referenced from:
_main in ccKuZb1g.o
"Poco::Exception::displayText() const", referenced from:
_main in ccKuZb1g.o
"typeinfo for Poco::Exception", referenced from:
GCC_except_table1 in ccKuZb1g.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
Have been struggling with this for couple of hours. Any idea how to fix this? Thanks in advance!
the Poco::URI, Poco::StreamCopier classes are in the PocoFoundation library, so you will need to link to that library also.
g++ -o http_get http_get.cc -lPocoNet -lPocoFoundation
You don't appear to have specified the include path for the library and the library to use when compiling your source.
You need to provide the -I and the -L directive to g++ to specify the include path for the library and the library itself respsectively.