title: python dll return value is wrong
body: <p>I have made a dll which contains the code:</p>
  
  <pre class="lang-c prettyprint-override"><code>#pragma once
  
  extern double __declspec(dllexport) add(double a, double b);
  extern double __declspec(dllexport) dif(double a, double b);
  
  #include "testdll.h"
  
  double add(double a, double b)
  {
      return a + b;
  }
  
  double dif(double a, double b)
  {
      return a - b;
  } 
  </code></pre>
  
  <p>The python code which calls the add function:</p>
  
  <pre><code>    a = ctypes.c_double(1);
      b = ctypes.c_double(2);
      mydll = ctypes.CDLL('testDll.dll');
      mydll.restype = ctypes.c_double;
      ret  = mydll.AddNumbers(a, b);
  </code></pre>
  
  <p>The problem is that the add function doesnt return a+b but a screwd up value: 2619340</p>
  
  <p>Please help</p>