ZipArchive: Exceptions Handling

Exceptions Handling

Applies To: All

Introduction
STL Version
MFC Version
See Also API Links

Introduction

The ZipArchive Library uses exceptions to notify about errors occurred while processing an archive.
If an exception is thrown while processing an archive, you should release the used resources by calling CZipArchive::Close() with the CZipArchive::afAfterException or
CZipArchive::afWriteDir value.
If an exception happened during extraction, instead of calling CZipArchive::Close(), you can call CZipArchive::CloseFile() with the bAfterException parameter set to true. Then you can for example proceed to extracting of a next file.
The ZipArchive Library compiles by default with its own set of error messages. If you want to disable their compilation (e.g. to make the compiled library smaller), undefine _ZIP_ENABLE_ERROR_DESCRIPTION in the ZipException.cpp file.
When you need to throw a CZipException in a way that it works uniformly in STL and MFC version, use the CZipException::Throw() method.
The reason for the exception is stored in the CZipException::m_iCause member variable and the error code reported by the system is stored in CZipException::m_iSystemError.

STL Version

In the STL version, the ZipArchive Library throws exceptions inherited from std::exception. When catching exceptions, you should catch a reference to an exception object, not a pointer to it.

Sample Code

CZipArchive zip;
try
{
    zip.Open(_T("C:\\Temp\\test.zip"));
    // ... do some processing here
    zip.Close();
}
catch(CZipException& ex)
{
    // display the exception message
    _tprintf(_T("Error while processing an archive: %s"), 
        (LPCTSTR)ex.GetErrorDescription());
    // close the archive safely releasing resources;
    // the archive will most probably be not usable after this call,
    // if it was modified
    zip.Close(CZipArchive::afAfterException);
}

MFC Version

In the MFC version, the ZipArchive Library throws exceptions inherited from CException. When catching exceptions, you should catch a pointer to an exception object and delete the object after you have finished handling the exception.

Sample Code

CZipArchive zip;
try
{
    zip.Open(_T("C:\\Temp\\test.zip"));
    // ... do some processing here
    zip.Close();
}
catch(CException* ex)
{
    // display the exception message
    TCHAR lpszError[1024];
    ex->GetErrorMessage(lpszError, 1024);
    _tprintf(_T("Error while processing an archive: %s"), lpszError);
    if (ex->IsKindOf( RUNTIME_CLASS( CZipException )))
    {
        CZipException* p = (CZipException*) ex;
        // ... retrieve detailed information about the exception
    }
    else if (ex->IsKindOf( RUNTIME_CLASS( CFileException )))
    {
        CFileException* p = (CFileException*) ex;
        // ... retrieve detailed information about the exception
    } 
    else
    {
        //... and so on
    }        
    ex->Delete();
    // close the archive writing a central directory
    // (makes sense if the archive was modified);
    // the archive should be usable after this call
    zip.Close(CZipArchive::afWriteDir);
}

Introduction

STL Version

MFC Version

See Also API Links