title: Mex runtime error: Unexpected standard expression
body: <p>I am new to Mex. After building a C++ Mex file, I get this error immediately at runtime.</p>
  
  <pre><code>&gt;&gt; [a b c] = read_svm('/All/testhalf_Anger_1.libsvm');
  Unexpected Standard exception from MEX file.
  What() is:basic_string::_S_construct NULL not valid
  ..
  </code></pre>
  
  <p>This is what the execution of my code looks like </p>
  
  <p>Thank You in advance!</p>