title: c++ error: expected primary-expression before '&' token
body: <p>I'm learning c++ and I have the following code which gives an error in line 39 (fill_file() call).  I've searched on the web for a solution but can't find why I get this error (expected primary-expression before '&amp;' token).</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;string&gt;
  #include &lt;vector&gt;
  #include "../std_lib_facilities.h"
  using namespace std;
  
  struct Point {
      double x;
      double y;
  };
  
  void fill_file(vector&lt;Point&gt;&amp; original_points) {
      string outputfile="mydata.txt";
      ofstream ost{outputfile};
      if(!ost) error("Can't open outputfile ", outputfile);
      for(int i=0;i&lt;original_points.size();i++) {
          ost &lt;&lt; original_points[i].x &lt;&lt; " " &lt;&lt; original_points[i].y &lt;&lt; endl;
      }
  }
  
  int main() {
      cout &lt;&lt; "Please enter 3 points with a value: " &lt;&lt; endl;
      vector&lt;Point&gt; original_points;
      Point p;
      double x;
      double y;
      for(int i=0;i&lt;3;i++) {
          cin&gt;&gt;p.x;
          cin&gt;&gt;p.y;
          original_points.push_back(p);
      }
      cout &lt;&lt; endl;
      cout &lt;&lt; endl &lt;&lt; "Points: " &lt;&lt; endl;
      for(int i=0;i&lt;original_points.size();i++) {
          cout &lt;&lt; original_points[i].x &lt;&lt; " " &lt;&lt; original_points[i].y &lt;&lt; endl;
          /* ost &lt;&lt; original_points[i].x &lt;&lt; " " &lt;&lt; original_points[i].y &lt;&lt; endl; */
      }
      cout &lt;&lt; endl &lt;&lt; endl;
      fill_file(vector&lt;Point&gt;&amp; original_points);
      return 0;
  }
  </code></pre>
  
  <p>What am I doing wrong?  Thx for the help!!</p>