title: How to solve 'unresolved external symbol'
body: <p>I want to run the project <code>Objectness</code>, Main.cpp. The code I download from website. I just use C++ again after about 5 years.</p>
  
  <p>I have  errors 'unresolved external symbol'. I read a related problem '<a href="https://stackoverflow.com/questions/9928238/unresolved-external-symbol-no-idea">Unresolved external symbol in object files</a>'.<img src="https://i.stack.imgur.com/Z0NGd.jpg" alt="enter image description here"></p>
  
  <p>So I found these external symbols are already defined in <code>Objectness.cpp</code>. </p>
  
  <p>The exactly error are </p>
  
  <pre><code>1&gt;  Touching "x64\Debug\Objectness.unsuccessfulbuild".
  1&gt;ClCompile:
  1&gt;  All outputs are up-to-date.
  1&gt;ManifestResourceCompile:
  1&gt;  All outputs are up-to-date.
  1&gt;Objectness.obj : error LNK2019: unresolved external symbol destroy_param referenced in function "public: static class cv::Mat __cdecl Objectness::trainSVM(class cv::Mat const &amp;,class std::vector&lt;int,class std::allocator&lt;int&gt; &gt; const &amp;,int,double,double,double)" (?trainSVM@Objectness@@SA?AVMat@cv@@AEBV23@AEBV?$vector@HV?$allocator@H@std@@@std@@HNNN@Z)
  1&gt;Objectness.obj : error LNK2019: unresolved external symbol free_and_destroy_model referenced in function "public: static class cv::Mat __cdecl Objectness::trainSVM(class cv::Mat const &amp;,class std::vector&lt;int,class std::allocator&lt;int&gt; &gt; const &amp;,int,double,double,double)" (?trainSVM@Objectness@@SA?AVMat@cv@@AEBV23@AEBV?$vector@HV?$allocator@H@std@@@std@@HNNN@Z)
  1&gt;Objectness.obj : error LNK2019: unresolved external symbol train referenced in function "public: static class cv::Mat __cdecl Objectness::trainSVM(class cv::Mat const &amp;,class std::vector&lt;int,class std::allocator&lt;int&gt; &gt; const &amp;,int,double,double,double)" (?trainSVM@Objectness@@SA?AVMat@cv@@AEBV23@AEBV?$vector@HV?$allocator@H@std@@@std@@HNNN@Z)
  1&gt;Objectness.obj : error LNK2019: unresolved external symbol check_parameter referenced in function "public: static class cv::Mat __cdecl Objectness::trainSVM(class cv::Mat const &amp;,class std::vector&lt;int,class std::allocator&lt;int&gt; &gt; const &amp;,int,double,double,double)" (?trainSVM@Objectness@@SA?AVMat@cv@@AEBV23@AEBV?$vector@HV?$allocator@H@std@@@std@@HNNN@Z)
  1&gt;Objectness.obj : error LNK2019: unresolved external symbol set_print_string_function referenced in function "public: static class cv::Mat __cdecl Objectness::trainSVM(class cv::Mat const &amp;,class std::vector&lt;int,class std::allocator&lt;int&gt; &gt; const &amp;,int,double,double,double)" (?trainSVM@Objectness@@SA?AVMat@cv@@AEBV23@AEBV?$vector@HV?$allocator@H@std@@@std@@HNNN@Z)
  </code></pre>
  
  <p>Could anyone tell me how to solve this problem? Thanks in advance!</p>