C++ OpenCV未定义对的引用

我使用的是Ubuntu 16.04和OpenCV 2.4.9，我的简单示例程序经常无法构建。我在建克莱恩的房子

由于我是OpenCV的新手，我有一些问题需要解决。我尝试了两种不同的程序

第一个是这个：

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

int main(int argc, char **argv) {
    IplImage *img = cvLoadImage(argv[1]);
    cvNamedWindow("Example1", CV_WINDOW_AUTOSIZE );
    cvShowImage("Example1", img);
    cvWaitKey(0);
    cvReleaseImage(&img);
    cvDestroyWindow("Example1" );
}

我的第二个是：

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

int main( int argc, char** argv ) {

    cv::Mat image;
    image = cv::imread("sample.jpeg" , CV_LOAD_IMAGE_COLOR);

    if(! image.data ) {
        std::cout <<  "Could not open or find the image" << std::endl ;
        return -1;
    }

    cv::namedWindow( "Display window", cv::WINDOW_AUTOSIZE );
    cv::imshow( "Display window", image );

    cv::waitKey(0);
    return 0;
}

我不知道我做错了什么。 大多数搜索都会导致g++命令设置错误，但我认为CLion知道它在做什么（我也尝试过使用该命令，同样的错误）。 例如：

我假设

highgui

没有正确链接。在这种情况下，我的输出：

computervision@computervision-VirtualBox:~/ex$ pkg-config opencv --libs
/usr/local/lib/libopencv_core.so /usr/local/lib/libopencv_flann.so /usr/local/lib/libopencv_ml.so

看起来有点糟糕，我想我在安装过程中犯了一个错误（到底是哪个？）

另一个错误可能是CMakeLists.txt。建议对其进行更改。但是这条线

LIBRARIES += glog gflags protobuf leveldb snappy 

导致错误

执行

导出CMAKE_CXX_FLAGS=`pkg config opencv--cflags--libs`

在开始之前，CLion也没什么区别

编辑： 使用cmake：

computervision@computervision-VirtualBox:~/CLionProjects/untitled$ cmake .
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
OpenCV_LIBS: opencv_mlopencv_flannopencv_core
-- Configuring done
-- Generating done
-- Build files have been written to: /home/computervision/CLionProjects/untitled
computervision@computervision-VirtualBox:~/CLionProjects/untitled$ g++ -o untitled main.cpp `pkg-config opencv --cflags --libs` 
/tmp/ccdAr2hr.o: In function `main':
main.cpp:(.text+0x78): undefined reference to `cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x128): undefined reference to `cv::namedWindow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x1a2): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
main.cpp:(.text+0x1ca): undefined reference to `cv::waitKey(int)'
collect2: error: ld returned 1 exit status

---

缺少

CMakeLists.txt

中的链接

OpenCV

cmake_minimum_required(VERSION 3.9)
project(untitled)

set(CMAKE_CXX_STANDARD 11)
find_package( OpenCV REQUIRED ) # locate OpenCV in system
include_directories( ${OpenCV_INCLUDE_DIRS} ) # provide library headers
add_executable(untitled main.cpp)
target_link_libraries( untitled ${OpenCV_LIBS} /usr/lib/x86_64-linux-gnu/libopencv_highgui.so) # link OpenCV libraries , hightgui.so not found by cmake so this hack
MESSAGE("OpenCV_LIBS: " ${OpenCV_LIBS} )  #display opencv libs found

---

---

如果编译器找到OpenCV并且在执行

cmake

后，它应该显示找到的OpenCV库。

在

CMakeLists.txt

中缺少链接

OpenCV

cmake_minimum_required(VERSION 3.9)
project(untitled)

set(CMAKE_CXX_STANDARD 11)
find_package( OpenCV REQUIRED ) # locate OpenCV in system
include_directories( ${OpenCV_INCLUDE_DIRS} ) # provide library headers
add_executable(untitled main.cpp)
target_link_libraries( untitled ${OpenCV_LIBS} /usr/lib/x86_64-linux-gnu/libopencv_highgui.so) # link OpenCV libraries , hightgui.so not found by cmake so this hack
MESSAGE("OpenCV_LIBS: " ${OpenCV_LIBS} )  #display opencv libs found

---

---

---

如果编译器找到OpenCV，并且在执行

cmake

之后，它应该会显示找到的OpenCV库。

根据CMakeLists.txt，链接器args中缺少videoio和highgui库，您根本没有链接任何东西。

TARGET\u LINK\u LIBRARIES

命令在哪里？按照@nayab的建议添加了这两个命令。没有变化为什么在v3.1+可用时使用v2.4.9？通常情况下，首选“源代码外”版本，因为它们不会将所有的构建内容与版本控制下的源代码混合在一起。因此，您可以在包含

CMakeLists.txt

的目录下创建一个名为

build

的子目录，然后执行

cd build&&cmake..

链接器args中的videoio和highgui库基于您的CMakeLists.txt，您根本没有链接任何东西。

TARGET\u LINK\u LIBRARIES

命令在哪里？按照@nayab的建议添加了这两个命令。没有变化为什么在v3.1+可用时使用v2.4.9？通常情况下，首选“源代码外”版本，因为它们不会将所有的构建内容与版本控制下的源代码混合在一起。因此，您可以在包含

CMakeLists.txt

的目录下创建一个名为

build

的子目录，然后执行

cd build&&cmake..

无更改。试图用CLion和g++编译它。cmake找到OpenCV库了吗？恐怕我不太明白。如前所述，在执行cmake命令后，我对opencv非常陌生，它是否显示了库，因为我们添加了一条消息来显示找到的libs。正如您从“pkg config opencv--cflags--libs”的输出中所看到的，它只显示了3个库。我怀疑它的安装有问题。但是，在CMakeLists.txt中添加highgui库后，它应该可以工作。你能删除“CMakeCache.txt”并执行“cmake.”和“make”操作吗。试图用CLion和g++编译它。cmake找到OpenCV库了吗？恐怕我不太明白。如前所述，在执行cmake命令后，我对opencv非常陌生，它是否显示了库，因为我们添加了一条消息来显示找到的libs。正如您从“pkg config opencv--cflags--libs”的输出中所看到的，它只显示了3个库。我怀疑它的安装有问题。但是，在CMakeLists.txt中添加highgui库后，它应该可以工作。你能删除“CMakeCache.txt”并执行“cmake.”和“make”吗

computervision@computervision-VirtualBox:~/CLionProjects/untitled$ cmake .
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
OpenCV_LIBS: opencv_mlopencv_flannopencv_core
-- Configuring done
-- Generating done
-- Build files have been written to: /home/computervision/CLionProjects/untitled
computervision@computervision-VirtualBox:~/CLionProjects/untitled$ g++ -o untitled main.cpp `pkg-config opencv --cflags --libs` 
/tmp/ccdAr2hr.o: In function `main':
main.cpp:(.text+0x78): undefined reference to `cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x128): undefined reference to `cv::namedWindow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x1a2): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
main.cpp:(.text+0x1ca): undefined reference to `cv::waitKey(int)'
collect2: error: ld returned 1 exit status

computervision@computervision-VirtualBox:~/CLionProjects/untitled$ make 
Scanning dependencies of target untitled
[ 50%] Building CXX object CMakeFiles/untitled.dir/main.cpp.o
[100%] Linking CXX executable untitled
CMakeFiles/untitled.dir/main.cpp.o: In function `main':
main.cpp:(.text+0x78): undefined reference to `cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x128): undefined reference to `cv::namedWindow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
main.cpp:(.text+0x1a2): undefined reference to `cv::imshow(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&)'
main.cpp:(.text+0x1ca): undefined reference to `cv::waitKey(int)'
collect2: error: ld returned 1 exit status
CMakeFiles/untitled.dir/build.make:97: recipe for target 'untitled' failed
make[2]: *** [untitled] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/untitled.dir/all' failed
make[1]: *** [CMakeFiles/untitled.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2

cmake_minimum_required(VERSION 3.9)
project(untitled)

set(CMAKE_CXX_STANDARD 11)
find_package( OpenCV REQUIRED ) # locate OpenCV in system
include_directories( ${OpenCV_INCLUDE_DIRS} ) # provide library headers
add_executable(untitled main.cpp)
target_link_libraries( untitled ${OpenCV_LIBS} /usr/lib/x86_64-linux-gnu/libopencv_highgui.so) # link OpenCV libraries , hightgui.so not found by cmake so this hack
MESSAGE("OpenCV_LIBS: " ${OpenCV_LIBS} )  #display opencv libs found