Qt and opencv 3.4 error

Kira

Hello,
I was trying to run the opencv program in qt. When i run as a console application it works fine.
But when i include the above in widget it gives me error as follows:
dialog.obj:-1: error: LNK2019: unresolved external symbol "void __cdecl cv::fastFree(void *)" (?fastFree@cv@@YAXPEAX@Z) referenced in function "public: __cdecl cv::Mat::~Mat(void)" (??1Mat@cv@@QEAA@XZ)
dialog.obj:-1: error: LNK2019: unresolved external symbol "private: char * __cdecl cv::String::allocate(unsigned __int64)" (?allocate@String@cv@@AEAAPEAD_K@Z) referenced in function "public: __cdecl cv::String::String(char const *)" (??0String@cv@@QEAA@PEBD@Z)

I am qt using msvc 64 bit and my qt 64 bit.

I have also build opencv library on 64-bit visual studio 2017

jsulm

@Kira Do you link your app against opencv libraries?

Pablo J. Rogina

@Kira you may have an issue with the order of OpenCV's libraries and how they linked. You may want to take a look at this example as a guideline of how the libraries show be referred in your .pro file.