Question

代码很简单，基本上直接来自this教程。我正在运行Arch Linux并将OpenCV库存储在/usr/include/。我还检查过以确保/usr/include在我的PATH中。

#include <opencv/cv.h>
#include <opencv/highgui.h>
#include <iostream>

using namespace cv; 

int main(int argc, char** argv){
    Mat image;
    Mat grayImage; 

    if(!argv[1]){
        std::cerr << "No image data!" << std::endl;
        return -1; 
    }

    image = imread(argv[1], 1);
    cvtColor(image, grayImage, CV_BGR2GRAY);
    imwrite("Gray_Image.jpg", grayImage);

    namedWindow(argv[1], CV_WINDOW_AUTOSIZE);
    namedWindow("Gray Image", CV_WINDOW_AUTOSIZE);

    imshow(argv[1], image);
    imshow("Gray Image", grayImage);

    waitKey(0);
    return 0;
}

编译器进程成功查找并包含这些头文件，但我仍然在编译时得到未定义的引用错误。如果您查看我包含的头文件，他们还会在/usr/include/opencv2中包含其他文件。我检查过，这样的头文件确实存在。

有什么想法吗？

/tmp/ccudBcqD.o: In function `main':
test.cpp:(.text+0xc0): undefined reference to `cv::imread(std::string const&, int)'
test.cpp:(.text+0x11f): undefined reference to `cv::_OutputArray::_OutputArray(cv::Mat&)'
test.cpp:(.text+0x138): undefined reference to `cv::_InputArray::_InputArray(cv::Mat const&)'
test.cpp:(.text+0x158): undefined reference to `cv::cvtColor(cv::_InputArray const&, cv::_OutputArray const&, int, int)'
test.cpp:(.text+0x180): undefined reference to `cv::_InputArray::_InputArray(cv::Mat const&)'
test.cpp:(.text+0x1ca): undefined reference to `cv::imwrite(std::string const&, cv::_InputArray const&, std::vector<int, std::allocator<int> > const&)'
test.cpp:(.text+0x241): undefined reference to `cv::namedWindow(std::string const&, int)'
test.cpp:(.text+0x291): undefined reference to `cv::namedWindow(std::string const&, int)'
test.cpp:(.text+0x2bf): undefined reference to `cv::_InputArray::_InputArray(cv::Mat const&)'
test.cpp:(.text+0x2ff): undefined reference to `cv::imshow(std::string const&, cv::_InputArray const&)'
test.cpp:(.text+0x32d): undefined reference to `cv::_InputArray::_InputArray(cv::Mat const&)'
test.cpp:(.text+0x361): undefined reference to `cv::imshow(std::string const&, cv::_InputArray const&)'
test.cpp:(.text+0x383): undefined reference to `cv::waitKey(int)'
/tmp/ccudBcqD.o: In function `cv::Mat::~Mat()':
test.cpp:(.text._ZN2cv3MatD2Ev[_ZN2cv3MatD5Ev]+0x39): undefined reference to `cv::fastFree(void*)'
/tmp/ccudBcqD.o: In function `cv::Mat::operator=(cv::Mat const&)':
test.cpp:(.text._ZN2cv3MataSERKS0_[_ZN2cv3MataSERKS0_]+0x111): undefined reference to `cv::Mat::copySize(cv::Mat const&)'
/tmp/ccudBcqD.o: In function `cv::Mat::release()':
test.cpp:(.text._ZN2cv3Mat7releaseEv[_ZN2cv3Mat7releaseEv]+0x47): undefined reference to `cv::Mat::deallocate()'
collect2: error: ld returned 1 exit status
[Finished in 1.1s with exit code 1]
[shell_cmd: g++ "/home/branden/Desktop/OpenCV/test.cpp" -o "/home/branden/Desktop/OpenCV/test"]
[dir: /home/branden/Desktop/OpenCV]
[path: /usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/vendor_perl:/usr/bin/core_perl]

Answer 1

这是一个链接器问题。尝试：

g++ -o test_1 test_1.cpp `pkg-config opencv --cflags --libs`

这应该可以编译源代码。但是，如果您最近从源代码编译OpenCV，您将在运行时遇到链接问题，将找不到该库。在大多数情况下，在从源代码编译库之后，您需要最终完成：

sudo ldconfig

Answer 2

我已尝试过所有解决方案。评论中的-lopencv_core -lopencv_imgproc -lopencv_highgui解决了我的问题。并且知道我的命令行在geany中看起来像这样：

g++ -lopencv_core -lopencv_imgproc -lopencv_highgui  -o "%e" "%f"

当我建立时：

g++ -lopencv_core -lopencv_imgproc -lopencv_highgui  -o "opencv" "opencv.cpp" (in directory: /home/fedora/Desktop/Implementations)

标题是：

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

Answer 3

如果有人还有这个问题。一种解决方案是使用MinGW重建源OpenCV库，而不使用OpenCV提供的二进制文件。我做到了，它就像一个魅力。

Answer 4

按照tutorial进行操作。我在bash中运行了install-opencv.sh文件。它在教程中

从openCV

中读取示例

的CMakeLists.txt

cmake_minimum_required(VERSION 3.7)
project(openCVTest)
# cmake needs this line
cmake_minimum_required(VERSION 2.8)

# Define project name
project(opencv_example_project)

# Find OpenCV, you may need to set OpenCV_DIR variable
# to the absolute path to the directory containing OpenCVConfig.cmake file
# via the command line or GUI
find_package(OpenCV REQUIRED)

# If the package has been found, several variables will
# be set, you can find the full list with descriptions
# in the OpenCVConfig.cmake file.
# Print some message showing some of them
message(STATUS "OpenCV library status:")
message(STATUS "    version: ${OpenCV_VERSION}")
message(STATUS "    libraries: ${OpenCV_LIBS}")
message(STATUS "    include path: ${OpenCV_INCLUDE_DIRS}")

if(CMAKE_VERSION VERSION_LESS "2.8.11")
    # Add OpenCV headers location to your include paths
    include_directories(${OpenCV_INCLUDE_DIRS})
endif()

# Declare the executable target built from your sources
add_executable(main main.cpp)

# Link your application with OpenCV libraries
target_link_libraries(main ${OpenCV_LIBS})

的main.cpp

/**
 * @file LinearBlend.cpp
 * @brief Simple linear blender ( dst = alpha*src1 + beta*src2 )
 * @author OpenCV team
 */

#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <stdio.h>

using namespace cv;

/** Global Variables */
const int alpha_slider_max = 100;
int alpha_slider;
double alpha;
double beta;

/** Matrices to store images */
Mat src1;
Mat src2;
Mat dst;

//![on_trackbar]
/**
 * @function on_trackbar
 * @brief Callback for trackbar
 */
static void on_trackbar( int, void* )
{
    alpha = (double) alpha_slider/alpha_slider_max ;

    beta = ( 1.0 - alpha );

    addWeighted( src1, alpha, src2, beta, 0.0, dst);

    imshow( "Linear Blend", dst );
}
//![on_trackbar]

/**
 * @function main
 * @brief Main function
 */
int main( void )
{
    //![load]
    /// Read images ( both have to be of the same size and type )
    src1 = imread("../data/LinuxLogo.jpg");
    src2 = imread("../data/WindowsLogo.jpg");
    //![load]

    if( src1.empty() ) { printf("Error loading src1 \n"); return -1; }
    if( src2.empty() ) { printf("Error loading src2 \n"); return -1; }

    /// Initialize values
    alpha_slider = 0;

    //![window]
    namedWindow("Linear Blend", WINDOW_AUTOSIZE); // Create Window
    //![window]

    //![create_trackbar]
    char TrackbarName[50];
    sprintf( TrackbarName, "Alpha x %d", alpha_slider_max );
    createTrackbar( TrackbarName, "Linear Blend", &alpha_slider, alpha_slider_max, on_trackbar );
    //![create_trackbar]

    /// Show some stuff
    on_trackbar( alpha_slider, 0 );

    /// Wait until user press some key
    waitKey(0);
    return 0;
}

测试了linux mint 17

Answer 5

对我来说，这种类型的错误：

mingw-w64-x86_64/lib/gcc/x86_64-w64-mingw32/8.2.0/../../../../x86_64-w64-mingw32/bin/ld: mingw-w64-x86_64/x86_64-w64-mingw32/lib/libTransform360.a(VideoFrameTransform.cpp.obj):VideoFrameTransform.cpp:(.text+0xc7c):
undefined reference to `cv::Mat::Mat(cv::Mat const&, cv::Rect_<int> const&)'

有限的加载顺序，我必须像这样那样执行-lTransform360 -lopencv_dnn345 -lopencv...。而且将它们彼此并排也很有帮助，不要一开始就将-lTransform360放在最前面...否则，由于某些怪异的原因，您会得到：

undefined reference to `VideoFrameTransform_new'
undefined reference to `VideoFrameTransform_generateMapForPlane'

...

Answer 6

我在 linux 中编译 opencv4 后遇到了同样的错误。

我不得不在我的 .cpp 文件之后而不是之前链接库。

g++ $(pkg-config opencv4 --cflags) -std=c++17 foo.cpp $(pkg-config opencv4 --libs) -o foo.o

注意：我还将 -D OPENCV_GENERATE_PKGCONFIG=ON 传递给 cmake 命令以生成 pkgconfig/opencv4.pc 文件 - pkg-config 命令需要它。

阅读此处了解有关订单重要性的更多信息：Why does the order in which libraries are linked sometimes cause errors in GCC?

由于未定义的引用，无法让OpenCV编译？

6 个答案: