Example 504. Sample code for decompress a gzip file

// define the SFXZIPDecoder instance, _decoder, as class member variable
class MyClass {
private:
    SFXFile _file;
    SFXZIPDecoder _decoder;             // SFXZIPDecoder instance
    SFXAnsiStringStreamReader  _reader; // input stream for reading data from ZIPDecoder
    SFXAnsiString _unzipString;         // variable in which decompressed string is stored
public:
    Void Start(Void);

    // callback function declaration
    CALLBACK_DECLARE_SFXANSISTRINGSTREAMREADER(OnFetch)
};

Void MyClass::Start(Void)
{
    SFCError error; // error value

    // open file in read only mode
    if ((error = _file.OpenReadOnly(SFXPath("/testdata.tar.gz")))
        == SFERR_NO_ERROR) {

        // register file storage in ZIPDecoder
        if ((error = _decoder.Open(_file)) == SFERR_NO_ERROR) {

            // get input stream for reading data from ZIPDecoder
            if ((error = _decoder.GetStreamReader(&_reader))
                == SFERR_NO_ERROR) {

                // read data from ZIPDecoder into input stream
                // OnFetch function is notified of the completion of this operation
                if ((error = _reader.Fetch(CALLBACK_FUNCTION(OnFetch)))
                    != SFERR_NO_ERROR) {
                    // if error occurs
                    _reader.Release();
                }
            }
            if (error != SFERR_NO_ERROR) { 
                // if error occurs
                _decoder.Close();
            }
        }
        if (error != SFERR_NO_ERROR) { 
            // if error occurs
            _file.Close();
        }
    }
}

// callback function notified after reading data from ZIPDecoder
CALLBACK_IMPLEMENT_SFXANSISTRINGSTREAMREADER(MyClass, OnFetch, error)
{
    if (error == SFERR_NO_ERROR) {  
        // if no error

        // read decompressed data from input stream to _unzipString variable
        if ((error = _reader.ReadSFXAnsiString(&_unzipString)) == SFERR_NO_ERROR) {

            // display decompressed data
            TRACE("%s", _unzipString.GetCString());
        }
    }
    // close
    _decoder.Close();
    _file.Close();
}