Qt中的異常處理

1、看看Qt源碼中如何定義QT_TRY和QT_CATCH的： 

inline void qt_noop(void) {}

/* These wrap try/catch so we can switch off exceptions later.

   Beware - do not use more than one QT_CATCH per QT_TRY, and do not use
   the exception instance in the catch block.
   If you can't live with those constraints, don't use these macros.
   Use the QT_NO_EXCEPTIONS macro to protect your code instead.
*/

#ifdef QT_BOOTSTRAPPED
#  define QT_NO_EXCEPTIONS
#endif
#if !defined(QT_NO_EXCEPTIONS) && defined(Q_CC_GNU) && !defined (__EXCEPTIONS) && !defined(Q_MOC_RUN)
#  define QT_NO_EXCEPTIONS
#endif

#ifdef QT_NO_EXCEPTIONS
#  define QT_TRY if (true)
#  define QT_CATCH(A) else
#  define QT_THROW(A) qt_noop()
#  define QT_RETHROW qt_noop()
#else
#  define QT_TRY try
#  define QT_CATCH(A) catch (A)
#  define QT_THROW(A) throw A
#  define QT_RETHROW throw
#endif

2、我們來使用下QT的異常處理

// 在.pro 中增加如下配置 ==》 Qt默認是不開啓異常的
CONFIG += exceptions

// main.cpp

enum Except{ EXCEP_ZERO,EXCEP_ONE};

 void func(int a){
     if(a ==0) throw (EXCEP_ZERO); // 拋出異常
 }

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QT_TRY {
        func(1);
    } QT_CATCH(Except ex) {
        if(ex == EXCEP_ZERO) QT_RETHROW;
    }



    Widget w;
    w.show();
    return a.exec();
}