Opencv doesnt work, it prints error

1

Hello, i included opencv in a program:
#include
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
int main() {
cout << “Hello”;
}
and it is always prints error like: error: ‘recursive_mutex’ in namespace ‘std’ does not name a type (typedef std::recursive_mutex Mutex;)
and: error: ‘Mutex’ is not a member of ‘cv’ (typedef std::lock_guardcv::Mutex AutoLock;)
Can somebody help?

2

os ? opencv version ? compiler ?

3

crosspost: c++ - Opencv, many errors like ... in namespace 'cv' does not name a type - Stack Overflow

4

windows 10, 4.6.0 (i tried with other versions, always prints error), g++ (MinGW.org GCC-6.3.0-1) 6.3.0

6

try to get a more recent mingw. this one works:


C:\Users\admin>g++ --version
g++ (x86_64-posix-seh-rev0, Built by MinGW-W64 project) 8.1.0
7

Also, is OpenCV built for MingW, or the standard version, which is for Visual C++? If not, it should not work…

8

thanks you so much guys!

9

the prebuild binaries are indeed for VS only.
(problem above happened when building from src)

10

Thank you, the including is working, but if i compile this code:

#include <bits/stdc++.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
using namespace std;
int main() {
    cv::Mat image;
    return 0;
}

like: g++ main.cpp
then it will print an error:

c:/winlibs/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.2.1/../../../../x86_64-w64-mingw32/bin/ld.exe: C:\Users\TAKCSN~1\AppData\Local\Temp\ccKc8Dmu.o:g.cpp:(.text+0x1e): undefined reference to `cv::Mat::Mat()'
c:/winlibs/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.2.1/../../../../x86_64-w64-mingw32/bin/ld.exe: C:\Users\TAKCSN~1\AppData\Local\Temp\ccKc8Dmu.o:g.cpp:(.text+0x2f): undefined reference to `cv::Mat::~Mat()'

collect2.exe: error: ld returned 1 exit status
Can you help?

11

you additionally need to link your program against the opencv libs:

g++ main.cpp -lopencv_core460 -lopencv_highgui460
12

Hi, i want to ask how can i link it, should i give the path?

13

-L path/to/your/lib/folder

14

Thank you very much, you helped me a lot!

15

Hi, unfortunately it does not work.
I have this code:
#include <bits/stdc++.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui.hpp>
using namespace std;
int main() {
cv::Mat image;
return 0;
}

and I tried a lot of options to link the library, but it returns error.
I tried to use these paths:
g++ main.cpp -L C:/opencv/build/include/opencv2/
g++ main.cpp -L C:\opencv\build\include\opencv2\highgui\

and the error remained the same: undefined reference to `cv::Mat::Mat()’
Can you help?
Because i would like to solve this program very much.
It’s a challange for me.

16

-L needs path to the installed libs, not the headers