title: C++ compiler error definition of implicitly declared
body: <p>Hello everyone having anissue with my code today. I have created a program calculating area of square circle and rectangle. With a base class of shape. Where the UML has shape as the abstract class with public area():double, getName():string,and getDimensions:string, rectangle derived from shape with protected height, and width, and a public rectangle(h:double, w:double), followed by a derived square from rectangle with just a public square(h:double), and finally a circle derived from shape with a private radius, and a public circle(r:double).
  So far have gotten far in my code yet in my shape.cpp file am getting an error on line 10 that says shape.cpp:10: error: definition of implicitly-declared 'constexpr shape::shape()'
   shape::shape()</p>
  
  <p>here is a link to my complete code: <a href="https://gist.github.com/anonymous/0eedd7719a34655488fb" rel="nofollow">https://gist.github.com/anonymous/0eedd7719a34655488fb</a></p>
  
  <p>shape.cpp file:</p>
  
  <pre><code>#include "shape.h"
  #include "circle.h"
  #include "rectangle.h"
  #include "square.h"
  #include &lt;QDebug&gt;
  #include &lt;QString&gt;
  #include &lt;iostream&gt;
  using namespace std;
  
  shape::shape()
  {
  
  };
  </code></pre>
  
  <p>your help is appreciated </p>