title: Error when Overloading the operator <<
body: <pre><code>_3DTocka operator&lt;&lt;(ostream&amp; os, _3DTocka _3D){
      cout &lt;&lt; "(" &lt;&lt; _3D.x &lt;&lt; "," &lt;&lt; _3D.y &lt;&lt; "," &lt;&lt; _3D.z &lt;&lt; ")" &lt;&lt; endl;
  }
  </code></pre>
  
  <p>The above is my code and it gives an error:
  it must take exactly one argument (1 line)</p>
  
  <p>_3DTocka is the name of the class..</p>