OpenCV架构x86_64的未定义符号:错误

Question

在此之前被标记为重复问题请阅读结束.谢谢你的期待.

我用home-brew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suing后得到的错误g++ test.cpp -o test.

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)

我确实发现类似的堆栈溢出问题,但没有使用自制程序,我不知道时间敏感(关于更新和更改OpenCV,我的操作系统等)的问题是.我正在使用10.9.4操作系统的mac.这些答案对我来说并不是很清楚应该改变什么.许多人只是提出了一行代码而没有说明该行应该去哪里.我对这些技术非常新手.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的:库未加载:/usr/local/Cellar/opencv/2.4.9/include/./Test原因::LIB/libopencv_calib3d.2.4.dylib从引用未找到图像[2]完成克++ $( pkg-config --cflags --libs opencv)test.cpp -o Test Trace/BPT trap:5

brewdoctor给了我这样的警告:警告:取消关联小桶在你的地窖离开小桶断开链接可能导致集结麻烦,导致依赖于那些酒桶酿造到无法正常运行一旦建成.运行brew link这些:

opencv

所以我运行brew链接--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链接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pkg-config,所以我建议:

brew install pkg-config

然后你可能要重新安装opencv

brew reinstall opencv

或者可能

brew uninstall opencv
brew install opencv

然后你应该能够做到:

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

你可以跑

pkg-config --cflags --libs opencv4

g++如果你感兴趣的话,看看它为编译器输出了什么- 它告诉编译器库和头文件的位置.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

如果您不熟悉pkgconfig,可以要求它告诉您它知道的所有包裹,如下所示:

pkg-config --list-all

我的系统提供如下输出:

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,上面列表的每一行中的第一个单词告诉您包的名称pkgconfig知道,这是您在运行命令时应指定的名称,例如

pkg-config --cflags --libs opencv4

如果您的系统有点混乱,您可以找到使用如下的.pc文件pkgconfig:

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

要么

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,如下所示:

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

如果它们都正确编译,你可以运行它

./test

Answer 2

您收到这些错误是因为您在代码中使用了未链接到项目的OpenCV方法.

到目前为止,您只包括:

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>

但是要运行代码,您需要的远远超过这两个OpenCV库.例如,在尝试在XCODE中构建项目时,我们会出现以下错误:

Undefined symbols for architecture x86_64:
  "cv::imread(cv::String const&, int)", referenced from:
      _main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

这对应于您错误的这一部分:

...  "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  ...

发生这种情况是因为XCODE希望在您的代码中执行以下函数:

Mat img = imread("my_image.jpg", CV_LOAD_IMAGE_UNCHANGED);

但是你实现它的方式,它不知道imread()是什么,因为缺少对opencv库的引用!解决这个特殊问题的图书馆是:

libopencv_imgcodecs.3.1.0.dylib

(当然版本取决于您使用的OpenCV版本.)

要解决此特定错误,您必须执行两个步骤:

1. 将库添加到项目中:右键单击项目文件.单击"将文件添加到blabla",然后浏览到您的OpenCV目录.图书馆应位于

/Users/YOURNAME/YOURFOLDER/opencv-3.1.0/build/lib

警告!这可能取决于您如何安装OpenCV!如果您使用Homebrew安装它.目录应该在这里:

/usr/local/Cellar/opencv/2.4.9/lib

选择以下库(libopencv_imgcodecs.3.1.0.dylib)并将其添加到项目中:

将库添加到项目后,它应显示在左侧的列表中.Double检查您是否选择了正确的库.其中一些名字非常相似!

2. 在C++文件中包含库

正如你所做的那样:

#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>

您现在应该继续并包含新库:

#include "opencv2/imgcodecs/imgcodecs.hpp"

3. 运行你的程序

再次构建程序时,应该少一个错误.并且XCODE应该没有问题来运行 cv :: imread.

由于您有很多错误,现在应该继续检查成功构建程序所需的库.

我建议链接这些库,因为它们很常见:

#include <iostream>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
#include "opencv2/video/video.hpp"
#include "opencv2/imgcodecs/imgcodecs.hpp"

在对所有错误进行疯狂之前,您可以链接所有库并查看它是否正确构建.