I installed the opencv library by using apt:

sudo apt install libopencv-dev libopencv-contrib-dev

But how to involve the installed library into my own project without using cmake? I tried directly including the headers but failed:

#include<opencv2/opencv.hpp>


int main(){
    cv::Mat mat;

    return 0;
}

By the way, I compile the project by g++:

g++ tt_opencv.cpp -o test

Should i add an -I{path} option when compiling?