Netbeans:Appcrash在运行时(2d动态数组）

我被要求制作一个2d动态数组，大小等于M*M（用户输入），列和行的大小都是M。

我的问题是输入M和K值后，应用程序崩溃。

我不完全理解构造函数和析构函数在动态数组中的使用，所以我认为我缺少一些东西。如有任何帮助，我们将不胜感激！：）

#include <iostream>
#include <iomanip>
#include <new>
#include <cmath>
using namespace std;
class Board {
private:
    bool gameOver; //true if game is finished.
    int K; // number of consecutive stones needed to win.
    //int board [][];
    int M;
    int **ptr; // pointer to a pointer(**)
public:
    Board();
    ~Board();
    void getBoardSize();
    void setArrayIndex();
    void printBoard();
    int getComputerInput();
    int getPlayerInput();
    void setIndexValue(int, int);   
    };
//Constructor to initiate variables.
Board::Board(){
    gameOver = false;
    M = 0;
    K = 0;
    //board [*M][*M];
    ptr = new int*[M]; // create new array of pointers to int objects.
    for (int i=0; i < M; i++){
        ptr[i] = new int[M];
    }
}
//The destructor to release the heap memory.
Board::~Board(){ 
    for (int i=0;i<M; i++){
        delete [] ptr[i];
    }
    delete[] ptr;
}

void Board::getBoardSize(){
    cout << "Enter value for M ( > 2): " << endl;
    cin >> M;
    cout << "Enter value for K ( > 1): " << endl;
    cin >> K;
}
void Board::setArrayIndex(){
    for (int i=0; i < M; i++){
        for (int j=0; j < M; j++){
            ptr [i][j] = 0;
        }
    }
}
void Board::printBoard(){
    for (int i=0; i < M; i++){ 
        cout << setw(4) << i+1;   //Print Column numbers first.  
    }
    cout << endl; //column headers done...
    for (int r=0; r < M; r++){      
        cout << setw(2) <<r+1 << " ";
        for (int c=0; c < M; c++){
            cout << ptr[r][c]; // index values printed.
            if (c+1 < M){   //to prevent the last "---".
                cout << "---";
            }
        }
        cout << endl;
        cout << setw(4);
        for (int j=0; j < M; j++){
            if (r+1 < M){   //to prevent the last "|".
                cout << "|";
            }
            cout << "   ";  
        }
        cout << endl;
    }
}
int Board::getComputerInput(){
    int x, y;
    cout << "PC: Input row and column (x, y) from 1 to M: " << endl;
    cin >> x;
    cin >> y;
    cout << "PC Plays " << "(" << x << ", " << y << ")" << endl;
    printBoard();
    return x-1, y-1;
}
int Board::getPlayerInput(){
    int x, y;
    cout << "Human: Input row and column (x, y) from 1 to M: " << endl;
    cin >> x;
    cin >> y;
    cout << "Human Plays " << "(" << x << ", " << y << ")" << endl;
    printBoard();
    return x-1, y-1;
}
void Board::setIndexValue(int a, int b){
    //ptr [a][b] = 
}

 #endif /* NEWFILE_H */

Main

#include <cstdlib>
#include <iostream>
using namespace std;

int main() {    
    Board object;
    object.getBoardSize();
    object.setArrayIndex();
    object.printBoard();
    //object.getComputerInput();
    //object.getPlayerInput();

    return 0;
}