c++ - OpenCV 架构 x86_64 的 undefined symbol : error

Question

在此问题被标记为重复问题之前，请阅读结尾。感谢观看。

我使用 Homebrew 软件设置了 openCV。

这些是我使用的命令:

brew tap homebrew/science
brew install opencv

我正在使用我在网上找到的以下简单文件来测试我的设置:

// Example showing how to read and write images
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;

int main(int argc, char** argv)
{   
    // Load an image from file - change this based on your image name
    Mat img = imread("my_image.jpg", CV_LOAD_IMAGE_UNCHANGED);

    if(img.empty())
    {
        fprintf(stderr, "failed to load input image\n");
        return -1;
    }

    // this is just to show, that you won't have to pre-alloc
    // result-images with c++ any more..
    Mat gray;
    cvtColor(img,gray,CV_BGR2GRAY);

    // Write the image to a file with a different name,
    // using a different image format -- .png instead of .jpg
    if( ! imwrite("my_image_copy.png", img) )
    {
        fprintf(stderr, "failed to write image file\n");
    }

    // no need to release anything with c++ !   
    return 0;
}

这是我在尝试编译和运行起诉 g++ test.cpp -o test 后遇到的错误。

Undefined symbols for architecture x86_64:
  "cv::_InputArray::_InputArray(cv::Mat const&)", referenced from:
      _main in test-41a30e.o
  "cv::namedWindow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int)", referenced from:
      _main in test-41a30e.o
  "cv::destroyWindow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
      _main in test-41a30e.o
  "cv::Mat::deallocate()", referenced from:
      cv::Mat::release() in test-41a30e.o
  "cv::imread(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int)", referenced from:
      _main in test-41a30e.o
  "cv::imshow(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, cv::_InputArray const&)", referenced from:
      _main in test-41a30e.o
  "cv::waitKey(int)", referenced from:
      _main in test-41a30e.o
  "cv::fastFree(void*)", referenced from:
      cv::Mat::~Mat() in test-41a30e.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我确实在堆栈溢出方面发现了类似的问题，但没有使用 Homebrew 软件，而且我不确定问题的时间敏感性(关于 OpenCV、我的操作系统等的更新和更改)。我正在使用带有 10.9.4 操作系统的 mac。这些答案对我来说也不是很清楚应该改变什么。许多人只是建议了一行代码，而没有说明该行应该去哪里。我对这些技术非常陌生。任何帮助都会非常感谢!

编辑:Mark Setchell 帮助解决了第一批错误。但我现在得到:g++ $(pkg-config --cflags --libs opencv) test.cpp -o Test & ./Test

[3] 7187dyld:库未加载:lib/libopencv_calib3d.2.4.dylib 引用自:/usr/local/Cellar/opencv/2.4.9/include/./Test 原因:找不到图片[2] 完成 g++ $(pkg-config --cflags --libs opencv) test.cpp -o 测试跟踪/BPT 陷阱:5

brewdoctor 给了我这个警告:警告:您的酒窖中有未连接的小桶不连接小桶可能会导致构建问题并导致依赖于那些小桶一旦建成就无法正常运行。在这些上运行 brew link:

opencv

所以我运行了 brew link --overwrite opencv 但得到了这个:

Linking /usr/local/Cellar/opencv/2.4.9... 
Error: Could not symlink include/opencv/cv.h

需要覆盖，因为 brew link opencv 给了

Linking /usr/local/Cellar/opencv/2.4.9... 
Error: Could not symlink include/opencv/cv.h
Target /usr/local/include/opencv/cv.h
already exists. You may want to remove it:
  rm /usr/local/include/opencv/cv.h

Answer 1

您收到链接器错误。我认为这是因为您没有链接到 opencv 需要的正确库。

获取正确库的最简单方法是使用 pkg-config，因此我建议:

brew install pkg-config

那你可能需要重新安装opencv

brew reinstall opencv

或许

brew uninstall opencv
brew install opencv

那么你应该可以做到:

g++ $(pkg-config --cflags --libs opencv) test.cpp -o Test 

你可以跑

pkg-config --cflags --libs opencv4

如果您有兴趣查看它为 g++ 编译器输出的内容 - 它会告诉编译器库和头文件在哪里。在我的系统上，它输出:

pkg-config --cflags --libs opencv4

-I/usr/local/Cellar/opencv/2.4.12_2/include/opencv \
-I/usr/local/Cellar/opencv/2.4.12_2/include \
-L/usr/local/Cellar/opencv/2.4.12_2/lib \
-lopencv_calib3d -lopencv_contrib -lopencv_core -lopencv_features2d -lopencv_flann -lopencv_gpu -lopencv_highgui -lopencv_imgproc -lopencv_legacy -lopencv_ml -lopencv_nonfree -lopencv_objdetect -lopencv_ocl -lopencv_photo -lopencv_stitching -lopencv_superres -lopencv_ts -lopencv_video -lopencv_videostab

如果你不熟悉pkgconfig，你可以要求它告诉你它知道的所有包，如下所示:

pkg-config --list-all

我的系统给出如下输出:

libzmq                              libzmq - 0MQ c++ library
gio-unix-2.0                        GIO unix specific APIs - unix specific headers for glib I/O library
glibmm-2.4                          glibmm - C++ wrapper for GLib
libpostproc                         libpostproc - FFmpeg postprocessing library
libgsf-1                            libgsf-1 - A library for reading and writing structured files (eg MS OLE and Zip)
gobject-introspection-no-export-1.0 gobject-introspection - GObject Introspection
libtasn1                            libtasn1 - Library for ASN.1 and DER manipulation
libusb-1.0                          libusb-1.0 - C API for USB device access from Linux, Mac OS X, Windows and OpenBSD/NetBSD userspace
gio-2.0                             GIO - glib I/O library
libusb                              libusb - USB access library (libusb-1.0 compat wrapper)
libecpg_compat                      libecpg_compat - PostgreSQL libecpg_compat library
QtNetwork                           Qtnetwork - Qtnetwork Library
opencv4                              OpenCV - Open Source Computer Vision Library

基本上，上面列表中每一行的第一个单词告诉你pkgconfig知道的包的名称，这是你在运行诸如

之类的命令时应该指定的名称

pkg-config --cflags --libs opencv4

如果你的系统有点乱，你可以像这样找到 pkgconfig 使用的 .pc 文件:

find /usr/local/Cellar -name \*.pc

或

find /usr/local/Cellar -name \*.pc | grep -i opencv

/usr/local/Cellar/opencv3/3.1.0_3/lib/pkgconfig/opencv.pc

然后直接使用配置文件，像这样:

pkg-config --cflags --libs /usr/local/Cellar/opencv3/3.1.0_3/lib/pkgconfig/opencv.pc 

如果一切编译正确，您可以使用

运行它

./test