/* Author : Paul Caron, alias ChillPill on sololearn About : This program reads and writes entries to a text file. I used the singleton model in this case, but I will change this model again for cases where you have multiple db files to manage. How to use : Just enter anything on separate lines. todo : create schema class. parse queries(search, add, delete, edit). eventually make this a multithreaded service. */ #include #include #include #define bar "====================\n" #define file_name "database.txt" using namespace std; //todo struct Schema{ string column_names[2]={"name","birthday"}; int column_max_chars[2]={30,30}; }; class DBmanager{ static DBmanager * singleton; private: fstream fs; DBmanager(){} public: ~DBmanager(){ fs.close(); } static DBmanager * instance(Schema schema){ if(DBmanager::singleton==NULL){ DBmanager::singleton = new DBmanager(); } return DBmanager::singleton; } void init(){ fs.open(file_name,ios::app|ios::in|ios::out); if(fs.is_open()){ cout<<"database open\n"; }else{ cout<<"database not open\n";} } void add(string s){ fs.clear();//reset the fs state from bad to good, in case it would be bad fs.seekp(0,ios::end);//puts pointer at end of file. fs << s <init(); cout<add(string("paul")); db->queryAll(); while(getline(cin,input)) db->add(input); cout << bar; db->queryAll(); cout << bar; //testing the singleton design DBmanager * db2 = DBmanager::instance(schema); db2->queryAll(); cout << bar; delete db; return 0; }

Database file - fstream - singleton