title: Why is QMutex unknown?
body: <p>I've included the QMutex  header and using it as seen below. But I get the following error:</p>
  
  <blockquote>
    <p>error C2146: syntax error : missing > ';' before identifier > '_RecorderParamsMutex' </p>
    
    <p>error C4430:  missing type specifier
    - int assumed. > Note: C++ does not support default-int</p>
    
    <p>error C4430: missing type specifier -> int assumed. Note: C++ does not > support default-int</p>
  </blockquote>
  
  <pre><code>#ifndef RECORDERinterface_h
      #define RECORDERinterface_h
      #include "qstring.h"
      #include "ccc.h"
      #include "ddd.h"
      #include &lt;qmutex.h&gt;
      #include "eee.h"
  
  using namespace Common; //for aaaaa
  
  class RecorderInterface{
      //the implemented recorders are my friends, the may access all my private stuff :)
      friend class A;
      friend class B;
  
  public:
      RecorderInterface();     
      bool            setParam(RecorderPrintParam *up);
  
  
  private:
      QMutex          _RecorderParamsMutex;
  };
  
  #endif
  </code></pre>