c++ - 使用2d数组时，为什么我的程序中出现段错误(核心转储)错误？

Question

我正在尝试用c++(https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life)创建Conway的生活游戏，我不知道为什么会引发此错误。这是我的代码:

#include <iostream>

using namespace std;
void Life() {
    //initializing all the variables needed
    int creatures;
    int row;
    int column;
    int neighbors = 0;
    int days = 0;
    char cont = 'c';
    //creates Board
    string Board[20][20];
    string NewBoard[20][20];
    //stores X for dead into all elements
    for (int r = 0; r <= 19; r++) {
        for (int c = 0; c <= 19; c++) {
            Board[r][c] = "X ";
        }
    }
    //asks for and stores the users coords
    cout<<"Enter the amount of creatures desired: ";
    cin>>creatures;
        for (int i = 0; i <= creatures - 1; i++) {
            cout<<"\nEnter the row of the next creature: ";
            cin>>row;
            cout<<"\nEnter the column of the next creature: ";
            cin>>column;
            Board[row - 1][column - 1] = "O ";
        }
    for (int r = 0; r <= 19; r++) {
        for (int c = 0; c <= 19; c++) {
            NewBoard[r][c] = Board[r][c];
        }
    }

    while (cont == 'c') {
        for (int r = 0; r <= 19; r++) {
            for (int c = 0; c <= 19; c++) {
                Board[r][c] = NewBoard[r][c];
            }
        }
        cout<<"\n\n\n\nDay "<<days<<"\n";
        //prints current board
        for (int r = 0; r <= 19; r++) {
            cout<<"\n";
            for (int c = 0; c <= 19; c++) {
                cout<<Board[r][c];
        }
    }
        cout<<"\n\n";
        //detects for alive creatures then checks them for neighbors
        for (int r = 0; r <= 19; r++) {

            for (int c = 0; c <= 19; c++) {
                //detects for life
                if (Board[r][c] == "O ") {
                    //detects for neighbors
                    neighbors = 0;
                    if (Board[r + 1][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r + 1][c] == "O ") {
                        neighbors++;
                    }
                    if (Board[r + 1][c - 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r][c - 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c - 1] == "O ") {
                        neighbors++;
                    }
                    //kills the creature if it has less than 2 or more than 3 living neighbors
                    if (neighbors < 2) {
                        NewBoard[r][c] = "X ";
                    }
                }
                //if creature is dead, checks to see how many live neighbors
                else {
                    neighbors = 0;
                    if (Board[r + 1][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r + 1][c] == "O ") {
                        neighbors++;
                    }
                    if (Board[r + 1][c - 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r][c - 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c + 1] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c] == "O ") {
                        neighbors++;
                    }
                    if (Board[r - 1][c - 1] == "O ") {
                        neighbors++;
                    }
                    //"resurrects" creature if it has 3 neighbors
                    if (neighbors == 3) {
                        NewBoard[r][c] = "O ";
                    }
                }
            }
        }
        //asks if user wants to continue
        cout<<"\n\nPress c to continue, q to quit: ";
        cin>>cont;
        days++;
    }
}

int main()
{
    Life();
    return 0;
}

抱歉，如果真的很难阅读(我仍在学习)。我已经得出结论，问题来自while循环的其他部分。为什么是这样？

Answer 1

    for (int r = 0; r <= 19; r++) {
        for (int c = 0; c <= 19; c++) {

在此循环中，您将同时使用 r和 c覆盖整个0-19。

                if (Board[r + 1][c + 1] == "O ") {
                    neighbors++;
                }

当 r或 c为19时，此处将尝试访问 Board[20][something]或 Board[something][20](当然不存在)。未定义的行为。崩溃

                if (Board[r - 1][c - 1] == "O ") {
                    neighbors++;
                }

同样，当 r或 c为0时，这将尝试访问负数组索引。未定义的行为。崩溃

上面仅是几乎所有 if语句都遭受的常见缺陷的示例:缺少适当的边界检查。