C++ 未定义对符号的引用，但库已链接

我试图用opencv 3.0构建一个应用程序，我得到了一个“未定义的符号错误引用”

我的问题是符号是在我链接到的库中定义的

编译命令：

g++ -o DisparityMap main.o tools.o emb.o moc_tools.o moc_emb.o -lopencv_highgui -lopencv_core -lopencv_imgproc -lopencv_imgcodecs -lopencv_calib3d -lQtGui -lQtCore -lpthread

我得到的错误是：

/usr/bin/ld: twowindow.o: undefined reference to symbol '_ZN2cv6String10deallocateEv'
//usr/local/lib/libopencv_core.so.3.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

但问题中的符号实际上是在我链接到的库中定义的：

scanelf -l -s _ZN2cv6String10deallocateEv | grep _ZN2cv6String10deallocateEv

ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_objdetect.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_photo.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_core.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_video.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_features2d.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_ml.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_highgui.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_videoio.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_stitching.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_videostab.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_superres.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_flann.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_imgproc.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_imgcodecs.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_calib3d.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_shape.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_objdetect.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_photo.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_core.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_video.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_features2d.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_ml.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_highgui.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_videoio.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_stitching.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_videostab.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_superres.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_flann.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_imgproc.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_imgcodecs.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_calib3d.so.3.0.0 
ET_DYN _ZN2cv6String10deallocateEv /usr/local/lib/libopencv_shape.so.3.0.0 

编译命令：

g++ -o DisparityMap main.o tools.o emb.o moc_tools.o moc_emb.o -lopencv_highgui -lopencv_core -lopencv_imgproc -lopencv_imgcodecs -lopencv_calib3d -lQtGui -lQtCore -lpthread

这不是编译命令，而是链接命令

我得到的错误是：

/usr/bin/ld: twowindow.o: undefined reference to symbol '_ZN2cv6String10deallocateEv'
//usr/local/lib/libopencv_core.so.3.0: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status

错误引用的是

twowindow.o

，它不在link命令中

因此，很难相信错误确实来自您发出的链接命令

---

最有可能的是，错误来自不同的link命令，并且该link命令上没有

-lopencv_core

。

在链接库之前，请给出带有-L标志的库的路径。

使用同一编译器构建的OpenCV和Qt？此外，请确保库在链接行上的顺序正确。库只能依赖于命令行上它后面的库。