Linking Error Opencv Qt '_ZN2cv6String10deallocateEv

Question

I am trying to make a qt program work with opencv without success. Qt, alone works. And opencv alone works (in Eclipse).

Here is my very simple C code from mainwindow.cpp file:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv2/opencv.hpp>

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
{
   ui->setupUi(this);

   cv::Mat image = cv::imread("my_image.png");
   cv::imshow("Display", image);

}

MainWindow::~MainWindow()
{
   delete ui;
}

And now my qmake file where there is maybe a problem, because of the linking : QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = test
TEMPLATE = app

INCLUDEPATH += /usr/local/include/opencv

SOURCES += main.cpp\
           mainwindow.cpp

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui

LIBS += -L/usr/local/lib \
        -lopencv_core \
        -lopencv_highgui \
        -lopencv_imgcodecs

And the worst (or the best) for the end, my awful error :

warning: libopencv_core.so.3.3, needed by /usr/local/lib/libopencv_imgcodecs.so, may conflict with libopencv_core.so.2.4

---

error: error adding symbols: DSO missing from command line /usr/local/lib/libopencv_core.so.3.3:
error: collect2: error: ld returned 1 exit status

I really hope that someone will read my message and could offer a solution. Maybe the best should be to uninstall and reinstall opencv or qt, I don't know.

Thanks,

Answer 1

Demangling the missing symbol:

$ c++filt -n _ZN2cv6String10deallocateEv
cv::String::deallocate()

You seem to be mixing objects or libraries using opencv2 and opencv3. I would check your system and make sure only one is installed.