title: Why visual studio 2017 opens a file called "mat.inl.hpp" when building my code?
body: <p>I am making a code in <code>c++</code> and <code>opencv 3.2</code> to capture live stream video and track hand motion. </p>
  
  <p>Then I measure the angle between a specified point on a drawn line and the hand centroid wherever it is.</p>
  
  <p>But when debugging a debug error appear like that : </p>
  
  <blockquote>
    <p>Unhandled exception at 0x00007FFD99459D98 in ROM.exe: Microsoft C++ exception: cv::Exception at memory location 0x000000E82DEFC640. occurred</p>
  </blockquote>
  
  <p>and opens a file called <code>mat.inl.hpp</code>, the mouse cursor is pointing to the return line in the following code :</p>
  
  <pre><code>    inline
  Mat&amp; Mat::operator = (const MatExpr&amp; e)
  {
      e.op-&gt;assign(e, *this);
      return *this;
  }
  </code></pre>
  
  <p>Please help me to solve this issue!</p>
  
  <p>Yes i used that class in the code many times, and i think that the first line of code which is causing the issue :-</p>
  
  <pre><code>Mat image = Mat::zeros(400, 400, CV_8UC3);
  
  line(image, CvPoint(200, 200), CvPoint(400, 200), Scalar(110, 220, 0), 2, 8);
  line(image, CvPoint(200, 200), CvPoint(X, Y), Scalar(110, 220, 0), 2, 8);
              double angle = atan2(Y, X);
              double b = (angle * 180 / 3.14159265);
              double a = abs((angle * 180 / 3.14159265));
              cout &lt;&lt; a;
  </code></pre>