Weird problem working with text files,can some one help?

ok, 1st thnx for read me.

the following is how the proggy read the file
fstream database;
database.open(filename,ios::in | ios::out);
  while (!database.eof())
  {
     database.getline(persona[cont].nombre,60,'\n');
     if(strlen(persona[cont].nombre)==0) {cont=0;break;}
     database.getline(persona[cont].telefono,20,'\n');
     database.getline(persona[cont].ciudad,30,'\n');
     database.getline(persona[cont].edad,10,'\n');
     cont++;
  }
database.close();

then this is how i save the file....

cont=0;
database.open(filename,ios::out);
database.seekg (0, ios::beg);
for(;cont<max;cont++)
   {
   database << persona[cont].nombre <<endl;
   database << persona[cont].telefono <<endl;
   database << persona[cont].ciudad << endl;
   database << persona[cont].edad <<endl;
   }
database.close();

well all that works fine when the proggy runs the 1st and 2nd time... but at the 3er time the file just get deleted well not deleted but all the data inside is missing :(...
i really need help.

Thnx again u guys.