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] 7187 dyld: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