C++ LList::begin方法代码示例

/*Function for adding row
	The spreadsheet is iterated till the position where the row is to be added. insert() is called to
	insert a row above the row values in user input. If the row is added to first position (0th position),
	head pointer is adjusted to point the row which is just inserted.
	*/
void addRow(LList<LList<Cell*>>& rows, int addRowValue){
	int h = 0; //increments to track the height or row value
	LList<Cell*> empty; //create an empty LinkedList of Cell type
	for (LList<LList<Cell*>>::iterator I = rows.begin(); I != rows.end(); I++){

		/*Insert a cell on the position if the value of the rows iterated equals to the value of row
		  in the user input where the row is to be inserted
		  */
		if (h == addRowValue)
		{
			for (LList<Cell*>::iterator J = (*I).begin(); J != (*I).end(); J++)
			{
				I = rows.insert(I, empty, addRowValue); //inserts a Cell in first column (0th column) at specific row position

				//Push backs empty LList at the back of the First cell till the width of column (last column)
				for (int k = 0; k < width; k++){
					(*I).push_back(new Cell());
				}
				break;
			}
		}
		h++;
	}

	//increase the height of the spreadsheet if a row is added
	height += 1;
}

/*Function for removing the row
	The spreadsheet is iterated till the position where the row is to be removed. remove() is called to
	remove a row at the row value position in user input. If last row is removed, tail pointer is adjusted
	and made to point the row above it. If first row (0th row) is removed, head pointer is adjusted adjusted
	to point next row.
	*/
void removeRow(LList<LList<Cell*>>& rows, int removeRowValue){
	int h = 0; //increments to track the height or row value
	LList<LList<Cell*>>::iterator I = rows.begin();
	for (LList<LList<Cell*>>::iterator I = rows.begin(); I != rows.end(); I++){

		/*Remove a cell on the position if the value of the rows iterated equals to the value of row
		in the user input where the row is to be removed.
		*/
		if (h == removeRowValue){
			I = rows.erase(I, removeRowValue, height);
		}
		h++;
	}

	//decrease the height of the spreadsheet by one if a row is removed
	height -= 1;
}

int main()
{

	LList<int> llist;
	LList<int>::iterator it = llist.begin();
	LList<int>::iterator it2 = llist.end();
	it2 = LList<int>::iterator(it);
#if 1
	it  = llist.insert(it,1);
	it  = llist.insert(it,2);
	it  = llist.insert(it,3);
	it = llist.begin();
	cout<<"--------insert-------------"<<endl;
	for(;it != llist.end();it++)
		cout<<*it<<endl;

	llist.clear();

	llist.push_back(11);
	llist.push_back(12);
	llist.push_back(13);
	llist.erase(llist.begin());
	cout<<"--------push_back-------------"<<endl;
	for(it=llist.begin();it != llist.end();it++)
		cout<<*it<<endl;
	llist.clear();
	cout<<"--------size-------------"<<llist.size()<<endl;
	llist.push_back(14);
	llist.push_back(15);
	llist.push_back(16);
	for(it=llist.begin();it != llist.end();it++)
		cout<<*it<<endl;
	cout<<"--------transfer-------------"<<llist.size()<<endl;
	LList<int>::iterator first= ++llist.begin();
	LList<int>::iterator last= llist.end();
	llist.transfer(++llist.begin(),++first,last);
	for(it=llist.begin();it != llist.end();it++)
		cout<<*it<<endl;
	cout<<"--------reverse-------------"<<llist.size()<<endl;
	llist.reverse();
	for(it=llist.begin();it != llist.end();it++)
		cout<<*it<<endl;
#endif		
	return 0;
}

/*Printing list
	The spreadsheet is iterated over height and width. The value to be printed is obtained using
	toString(). toString() returns the values of each cell in string format.
	*/
void printList(LList<LList<Cell*>>& rows){
	for (LList<LList<Cell*>>::iterator I = rows.begin(); I != rows.end(); I++) {
		for (LList<Cell*>::iterator J = (*I).begin(); J != (*I).end(); J++)
		{
			if (*J == (*I).back()){
				std::cout << (*J)->toString();
			}
			else{
				std::cout << (*J)->toString() << ",";
			}
		}
		std::cout << '\n';
	}
}

/*Replacing Base cell by numeric cell/ string cell/ function cell
	Empty spreadsheet has each element of Cell type, which is replaced by numericCell/stringCell/
	functionalCell based on the input arguments. Input Areguments:
	1) "number" -> numericCell
	2) "string" -> stringCell
	3) "max/min/mean" -> functionalCell
	*/
void insertNewCell(LList<LList<Cell*>>& rows, std::string& command, int column, int row, std::istringstream& ss, std::string& commandType){
	int h = 0;
	for (LList<LList<Cell*>>::iterator I = rows.begin(); I != rows.end(); I++) {
		h++; //keeps the track of Iteration over height or number of rows
		int w = 0; //keeps the track of Iteration over width or number of columns and always sets to 0 for new row
		for (LList<Cell*>::iterator J = (*I).begin(); J != (*I).end(); J++){
			w++;

			/*If row and column iterated equals to the value of row and column in user input, compare the type of
			  cell to be inserted (numericCell/stringCell/functionalCell)
			  */
			if (h == row && w == column){

				//If user input command is string type, create stringCell on that particular position
				if (commandType == "string"){
					delete *J;
					*J = new stringCell(command);
				}

				//If user input command is number type, create numericCell on that particular position
				else if (commandType == "number"){

					//Trying to convert String type into Double type. Throws Exception if unsuccessful
					try{
						double val = std::stod(std::string(command));
						delete *J;
						*J = new numericCell(val);

						/* Always calls updateSheet function after every number insertion/updation and modify
						   the value of functionCell if dependent.
						   */
						updateSheet(&rows);
					}
					catch (std::exception e){
						std::cout << "Error: Bad input for set number\n";
					}
				}

				/*If user input command is max/min/mean type, create functionalCell on that particular position implementing
				  max/min/mean function
				  */
				else if (commandType == "max" || commandType == "min" || commandType == "mean"){
					try{
						double rowValue = std::stod(std::string(command));
						int beginOffset = 0, endOffset = 0;
						ss >> beginOffset >> endOffset;
						double fVal = 0;
						functionCell(fVal, &rows, row, column, rowValue, beginOffset, endOffset, commandType);
					}
					catch (std::exception e){
						std::cout << "Error\n";
					}
				}
			}
		}
	}

	/* Calls updateSheet() after every insertion so as to update if two functioncells are dependent on
		each other.
		*/
	updateSheet(&rows);
}