C ++类中的二维动态数组[重复]

Question

我很难理解如何在一个类中声明一个数组并在同一个类的所有函数中使用它。数组大小取决于用户。

class Game{
 public:
    void createBoard();
    void gameStart();
    void inputBoard();
    void inputBoardSize();
    Game(int,int);


private:
    int rowChoice;
    int colChoice;
    int playerTurnRow;
    int playerTurnCol;
    string playerTurn;
    string board[rowChoice][colChoice];

};

Game::Game(int row,int col){
    rowChoice = row;
    colChoice = col;
    playerTurnRow = 0;
    playerTurnCol = 0;
    playerTurn = "R";
    board[row][col];
}

void Game::createBoard(){


        for (int arrayRow = 0;arrayRow < rowChoice;arrayRow++){
            for (int arrayCol = 0;arrayCol < colChoice;arrayCol++){
                board[arrayRow][arrayCol] = " ";
            }
}

我的声明可能有误，但我们将不胜感激

Answer 1

您的语法是有道理的，但这不是 C++ 的工作方式。除非您将该数组存储在堆上，否则标准数组只能是固定大小（在编译时定义，而不是动态生成）。

人们告诉您使用 STL 向量（来自 C++ 标准库）的原因是您不必管理在堆上存储标准二维数组，这意味着 new 和 delete 以及内存泄漏的可能性.

向量还允许您调整大小、为您进行边界检查，并且通常同样有效，因为它们以相同的方式存储数组（在内存中连续）。

这就是我的意思：

#include <iostream>
#include <vector>
#include <algorithm>

using std::cin;
using std::cout;
using std::endl;
using std::vector;

void standard_array_example(int r, int c)
{
  // here you are responsible for managing memory yourself
  // allocate an array on the heap, r * c sized
  char *board = new char[r * c];

  // fill the board with x's
  std::fill_n(board, r * c, 'x');

  for (int i = 0; i < r; i++)
  {
    for (int k = 0; k < c; k++)
    {
      cout << board[i * c + k] << " ";
    }
    cout << endl;
  }

  // you must manually free your memory, or else there is a leak
  delete[] board;
}

void vector_example(int r, int c)
{
  // here, your memory is managed for you. when board goes out of scope
  // it is destroyed. the scope here is the end of the function
  vector<vector<char>> board;
  for (int i = 0; i < r; i++)
  {
    board.push_back(vector<char>(c, 'x'));
  }

  for (auto r : board)
  {
    for (auto c : r)
    {
      cout << c << " ";
    }
    cout << endl;
  }
}

int main()
{
  int r, c;
  cin >> r;
  cin >> c;

  standard_array_example(r, c);
  cout << endl;
  vector_example(r, c);

  system("PAUSE");

  return 0;
}

两者功能相同：

5
5
x x x x x
x x x x x
x x x x x
x x x x x
x x x x x

x x x x x
x x x x x
x x x x x
x x x x x
x x x x x
Press any key to continue . . .