About persistance

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2 total messages Started by Maya Tue, 04 Mar 2003 19:37

#964

Author: Maya
Date: Tue, 04 Mar 2003 19:37

40 lines
2963 bytes

Hi!
Can someone please tell me what I am doing wrong in he below example. 
I really can't get it. I copied this from a book, and then adapted it to
my class, why is it not working?

class Date{
   int month;

   .........
public:
   void Write(std::fstream&);
   std::streampos Read(std::fstream&, std::streampos);
};

void Date::Write(std::fstream& rfs)throw(jme::Exception, jme::FileIOEx) {
    rfs.write(reinterpret_cast<char*> (&month), sizeof(month));
}
std::streampos Date::Read(std::fstream& rfs, 
                               std::streampos offset = std::ios::beg) 
                                    throw(jme::Exception, jme::FileIOEx) {
   char buffer[sizeof(size_t)];
 
   rfs.flush();
   rfs.seekp(offset);
   rfs.read(buffer, sizeof(int) );
   if(rfs.fail()){ std::cout <<  "Error\n";} // <== This gets displayed


   return rfs.tellp();

}

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Re: About persistance

#965

Author: osmium
Date: Tue, 04 Mar 2003 22:18

11 lines
1489 bytes

Maya writes:

> Can someone please tell me what I am doing wrong in he below example.
> I really can't get it. I copied this from a book, and then adapted it to
> my class, why is it not working?

<snip>

I don't have time to look at it.  But did you remember to 'rewind' after the
write and before the read?  Forgetting is a common error.

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