<blockquote>
<p>Add the following at the end of load_csv.hpp</p>
</blockquote>

<p>I think this would cause duplicate symbols, because I did not make the codes inline</p>

<blockquote>
<p>we just need to add load_csv.cpp to the CMakeLists.txt in that directory.</p>
</blockquote>

<p>I add load_csv.cpp to the CMakeLists.txt in <a href="https://github.com/mlpack/mlpack/pull/681/commits/0ceba31326b338c5b55af3c3a353e58006fcf68d">this commit</a>, still got the same error. </p>

<p>I include the header file, and the cpp into the CMakeLists.txt, make sure the include guard do not repeat with other headers(MLPACK_CORE_DATA_LOAD_CSV_HPP). Which  steps I missed?</p>

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