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SEH and C++ Exceptions - catch all in one

, 16 Mar 2000
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This article describes how to handle SE and C++ exception together.
  • Download demo project - 15 Kb
  • Download source files - 2 Kb
  • Motivation

    Everybody sometimes need to write as robust code as possible. The simplest way, in these cases, is to use exception handling. But most code is wrote in C++/MFC, with C++ exception handling (e.g. CdbException). With SEH, it is not possible to catch C++ exception, and C++ typed exception can not catch SE selectively, because it is not typed in a way of C++. Solution with catch(...) is not useful, because you will not know 'type' of exception. SE is possible to catch like unsigned int typed C++ exception, but this solution is not very nice.  

    Description of solution

    I was looking for a method to handle SE and C++ exception together. I found function

    typedef void (*_se_translator_function)( unsigned int, struct _EXCEPTION_POINTERS* );
    

    In MSDN you can find following description:

    The _set_se_translator function provides a way to handle Win32 exceptions (C structured exceptions) as C++ typed exceptions. To allow each C exception to be handled by a C++ catch handler, first define a C exception "wrapper" class that can be used, or derived from, in order to attribute a specific class type to a C exception. To use this class, install a custom C exception translator function that is called by the internal exception-handling mechanism each time a C exception is raised. Within your translator function, you can throw any typed exception that can be caught by a matching C++ catch handler.

    And now, it is enough to write wrapper class (I think, my class is quite better than class provided by documentation for _set_se_translator):

    class CSeException : public CException
    {
      DECLARE_DYNAMIC(CSeException)
          
    public: 
        CSeException(UINT nSeCode, _EXCEPTION_POINTERS* pExcPointers);
        CSeException(CSeException & CseExc);
    
        UINT GetSeCode(void);
        _EXCEPTION_POINTERS* GetSePointers(void);
        PVOID GetExceptionAddress(void);
    
        void Delete(void);
        int ReportError(UINT nType = MB_OK, UINT nIDHelp = 0);
        BOOL GetErrorMessage(CString & CsErrDescr, PUINT pnHelpContext = NULL);
        BOOL GetErrorMessage(LPTSTR lpszError, 
                             UINT nMaxError, 
                             PUINT pnHelpContext = NULL);
          
    private:
        UINT m_nSeCode;
        _EXCEPTION_POINTERS* m_pExcPointers;
    };
    

    And my own translator function:

    void SeTranslator(UINT nSeCode, _EXCEPTION_POINTERS* pExcPointers)
    {
       throw new CSeException(nSeCode,pExcPointers);
    }
    

    How does it work?

    When SE is raised, then it is called our own translator function - if it was installed through _se_translator_function. This translator function simply throw exception again, but now it is our wrapper class exception filled with useful information.

    Description of CSeException

    CSeException class is based on CException class provided by MFC. I overwrite some of useful methods, but it is working same way like any other exception class based on CException class - you can find description in documentation provided by Visual C++.

    Usage

    At first of all you need to install SeTranslator function, in every thread of your application. Translator function is  thread specific, it means it is not globally set in application. In single thread application it is possible to install it in constructor of application class (as I do in demo program), however in multithreading application it is best place to install translator function at the beginnings of every thread. When translator function is installed, then it is possible to write code like this:

    char *p = NULL;
    
    try {
    
      // do something ...
    
      p[0] = 0; 
    
      // do something ...
    
    } catch (CdbException dbError) {
    
      //handle it
    
    } catch(CSeException *e) {
      e->ReportError(MB_OK | MB_ICONSTOP);
      e->Delete();
    }
    

    CSeException class is Unicode and MBCS strings compliant. Please note, delete CSeException in catch() block, because it is dynamically allocated by translator function.

    License

    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here

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    About the Author

    Martin Ziacek
    Software Developer (Senior)
    United Kingdom United Kingdom
    No Biography provided

    Comments and Discussions

     
    QuestionLicense? Pinmemberjcastrovinci1-Feb-10 9:35 
    Questionunable to catch breakpoint exceptions Pinmemberhans.sch23-Nov-09 8:35 
    QuestionHow to do it well if _set_se_translator() is not available (WinCE) PinmemberBostjan Erzen26-Aug-08 1:41 
    QuestionAhoj Martin, prosba o pomoc Pinmemberriavale23-Mar-06 7:30 
    GeneralImproved Error Message for Access Violations PinmemberSteve Johnson (Sven)22-Mar-06 11:58 
    GeneralYou can't catch and continue on all PinmemberDB115-Oct-05 18:34 
    GeneralCompiler switch "/EHa" needed with VC 6 & 7 PinmemberJamireste28-Sep-05 6:43 
    Questionfloating point exceptions as well? Pinmembercptspiff28-Nov-03 2:00 
    Generalmore Exceptions Pinmembergertano24-Mar-03 8:52 
    GeneralRe: more Exceptions PinmemberMartyn Pearson18-Jun-03 1:19 
    GeneralRe: more Exceptions PinsussAnonymous2-Sep-04 0:10 
    GeneralQuestion about design. PinsussHoly Punk6-Feb-03 16:36 
    GeneralRe: Question about design. PinsussMike U.29-Apr-03 0:32 
    GeneralRelease mode weirdness Pinmemberbooster16-Nov-01 5:44 
    GeneralRe: Release mode weirdness PinmemberMartin Ziacek16-Nov-01 10:19 
    GeneralMFC Independent PinmemberAnonymous5-Nov-01 19:26 
    GeneralRe: MFC Independent PinmemberMartin Ziacek5-Nov-01 20:35 
    Questionmultiple calls i n a thread? PinmemberAnonymous22-Oct-01 9:12 
    I'm using win2k and xp thread pooling functions, is it ok to call _set_se_translator multiple times.. eg in the class constructor rather than at the start of the thread?
    AnswerRe: multiple calls i n a thread? PinmemberMartin Ziacek31-Oct-01 5:36 
    Questionwhat about exception type? PinmemberAnonymous22-Oct-01 8:47 
    AnswerRe: what about exception type? PinmemberMartin Ziacek31-Oct-01 5:30 
    GeneralThread Problem PinmemberThomas George10-Sep-01 11:37 
    GeneralRe: Thread Problem PinmemberMartin Ziacek10-Sep-01 12:01 
    GeneralRe: Thread Problem PinmemberThomas George10-Sep-01 13:49 
    GeneralRe: Thread Problem PinmemberMartin Ziacek10-Sep-01 20:01 

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