C++ DoublyLinkedList::begin方法代码示例

//reads a subset of database determined by memory capacity into a DoublyLinkedList
//subsequently sorts the list, iterates through it to merge entries with duplicate primary fields separated by delim
//and concatenate secondary fields using conn as the separator
//and exports it into a temp file
//returns the count of temporary files
int splitDatabase(string &database, const char delim, const char conn)
{
    ifstream fin(database);
    ofstream fout;
    int tempFileCount = 0;
    for (char buffer[LINE_BUFFER_SIZE]; fin.getline(buffer,LINE_BUFFER_SIZE,'\n');)
    {
        static int charsRead;
        static string tempFileName = string("temp") + to_string(tempFileCount++) + ".db";
        static string lineRead = "";
        static DoublyLinkedList<string> lines;

        lineRead += buffer;
        charsRead += fin.gcount();

        //if \n was not found by getline
        if(fin.fail())
        {
            fin.clear();
        }
        else
        {
            lines.add(lineRead);
            lineRead = "";
            if(charsRead > CHARS_ALLOWED_IN_MEMORY || fin.eof())
            {
                fout.open(tempFileName);
                lines.sort();

                for (DoublyLinkedList<string>::iterator iter = lines.begin(), jter = iter.next();
                        !iter.isNull(); iter = jter, jter = iter.next())
                {
                    //if jter is not a null node
                    //and the first field of iter (iter[0] -> iter.find(delim)) is equal to the first field of jter
                    //append the second field of jter to the second field of iter separated by conn
                    //repeat until the first fields differ or jter goes out of the bounds of the list
                    while(!jter.isNull() && (*iter).substr(0,(*iter).find(delim)) == (*jter).substr(0,(*jter).find(delim)))
                    {
                        *iter += conn + (*jter).substr((*jter).find(delim)+1);
                        ++jter;
                    }
                    //store iter in the current temporary database file
                    fout << *iter << endl;
                }

                fout.close();
                tempFileName = string("temp") + to_string(tempFileCount++) + ".db";
                lines.clearList();
                charsRead = 0;
            }
        }
    }
    fin.close();
    return tempFileCount-1;
}

int _tmain(int argc, _TCHAR* argv[])
{


	
	cout << "Lista Doblemente Enlazada de Int" << endl;
	DoublyLinkedList<int> l;
	l.insertarFinal(2);
	l.insertarFinal(4);
	l.insertarFinal(5);
	l.insertarInicio(6);
	l.insertar(8, 2);
	cout << l;
	cout << endl;
	l.remover(3);
	cout << l;
	cout << endl;
	cout << l.getElemento(2);
	cout << endl;

	cout <<"Inicia el iterador Preincremento"<< endl;
	// Probar Iteradores
	Iterador<int> it = l.begin();
	while (it != l.end()) {
		cout << *it << endl;
		++it;
	}

	cout << "Inicia el iterador Postincremento" << endl;
	// Probar Iteradores posincremento
	Iterador<int> itB = l.begin();
	while (itB != l.end()) {
		cout << *(itB++) << endl;
	}
	cout << endl;
	
	cout << "Inicia el iterador Predecremento" << endl;
	// Probar Iteradores
	Iterador<int> itC = l.rBegin();
	while (itC != l.rEnd()) {
		cout << *itC << endl;
		--itC;
	}

	cout << "Inicia el iterador Postdecremento" << endl;
	// Probar Iteradores posincremento
	Iterador<int> itD = l.rBegin();
	while (itD != l.rEnd()) {
		cout << *(itD--) << endl;
	}
	cout << endl;


	cout << "Lista Doblemente Enlazada de Double" << endl;
	DoublyLinkedList<double> lD;
	lD.insertarFinal(2.5);
	lD.insertarFinal(6.4);
	lD.insertarFinal(7.5);
	lD.insertarInicio(6.1);
	lD.insertar(89.1, 2);
	cout << lD;
	cout << endl;

	cout << "Inicia el iterador Preincremento" << endl;
	// Probar Iteradores
	Iterador<double> it1 = lD.begin();
	while (it1 != lD.end()) {
		cout << *it1 << endl;
		++it1;
	}

	cout << "Inicia el iterador Postincremento" << endl;
	// Probar Iteradores posincremento
	Iterador<double> it2 = lD.begin();
	while (it2 != lD.end()) {
		cout << *(it2++) << endl;
	}
	cout << endl;

	cout << "Inicia el iterador Predecremento" << endl;
	// Probar Iteradores
	Iterador<double> it3 = lD.rBegin();
	while (it3 != lD.rEnd()) {
		cout << *it3 << endl;
		--it3;
	}

	cout << "Inicia el iterador Postdecremento" << endl;
	// Probar Iteradores posincremento
	Iterador<double> it4 = lD.rBegin();
	while (it4 != lD.rEnd()) {
		cout << *(it4--) << endl;
	}
	cout << endl;

	cout << "Lista Doblemente Enlazada de Char" << endl;
	DoublyLinkedList<char> lC;
	lC.insertarFinal('a');
	lC.insertarFinal('$');
	lC.insertarFinal('r');
//.........这里部分代码省略.........