Question

我写了一个名为“nqueens”的迷你游戏，它利用数组代表棋盘。我为游戏写了5个函数。但是，每次游戏到达时：

if (checkGameEnd(board, queenNumber) == 1) {
    if (checkResult(board) == 1) {
        cout << "Yeah! Problem Solved." << endl;
    } else {
        cout << "Oops! Not enough queens." << endl;
    }
    break;
}

在main函数中，它显示了ABORT TRAP（6）。我在这个论坛上搜索了类似的帖子，大部分帖子都说ABORT TRAP与访问我们不拥有的内存有关。但我不知道我的代码的哪一部分正在访问无主内存。有人能找出问题吗？非常感谢。

要进入checkGameEnd == 1，请在游戏中键入I 8，K 7，J 10，L 9，B 17，A 15。

完整代码：

#include <iostream>
#include <iomanip>

using namespace std;
const int N = 18;

void printBoard(int [N][N], int);
int getAndProcessInput(int [N][N], int&, int&);
void flipBoard(int [N][N], int, int, int&);
int checkGameEnd(int [N][N], int);
int checkResult(int [N][N]);

int main(int argc, char *argv[]) {
    int board[N][N] = {0};
    int rowNumber, columnNumber, queenNumber = 0;

    while (1) {
        printBoard(board, queenNumber);
        if (checkGameEnd(board, queenNumber) == 1) {
            if (checkResult(board) == 1) {
                cout << "Yeah! Problem Solved." << endl;
            } else {
                cout << "Oops! Not enough queens." << endl;
            }
            break;
        }
        while (getAndProcessInput(board, rowNumber, columnNumber) != 0){
            cout << "Invalid. Try again!" << endl;
        }
        flipBoard(board, rowNumber, columnNumber, queenNumber);
    }
}

void printBoard(int board[N][N], int queenNumber) {
    cout << "   ";
    for (int i = 65; i < 65+N; i++) {
        char columnLetter = i;
        cout << columnLetter << " ";
    }
    cout << endl;

    for (int j = 0; j < N; j++) {
        cout << setw(2) << j << " ";
        for (int k = 0; k < N; k++) {
            if (board[j][k] == 0) {
                cout << ". ";
            } else if (board[j][k] == 1) {
                cout << "= ";
            } else if (board[j][k] == 2) {
                cout << "Q ";
            }
        }
        cout << endl;
    }

    cout << "No. of Queens = " << queenNumber << endl;
}

int getAndProcessInput (int board[N][N], int& rowNumber, int& columnNumber) {
    char column;

    cout << "Make a move (col row): ";
    cin >> column >> rowNumber;

    if (column < 'A' || column > 'Z') {
        return 1;
    }

    columnNumber = (int)column - 65;

    if (columnNumber < 0 || columnNumber >= N) {
        return 1;
    } else if (rowNumber < 0 || rowNumber >= N) {
        return 1;
    }

    if (board[rowNumber][columnNumber] != 0) {
        return 1;
    }

    return 0;
}

void flipBoard(int board[N][N], int rowNumber, int columnNumber, int& queenNumber) {
    int a, b;

    board[rowNumber][columnNumber] = 2;

    //flip in north-east direction
    a = rowNumber - 1;
    b = columnNumber + 1;
    while (a >= 0 && b < N) {
        board[a][b] = 1;
        a--;
        b++;
    }


    //flip in east direction
    a = rowNumber;
    b = columnNumber + 1;
    while (b < N) {
        board[a][b] = 1;
        b++;
    }



    //flip in south-east direction
    a = rowNumber + 1;
    b = columnNumber + 1;
    while (a <= N && b < N) {
        board[a][b] = 1;
        a++;
        b++;
    }



    //flip in south direction
    a = rowNumber + 1;
    b = columnNumber;
    while (a < N) {
        board[a][b] = 1;
        a++;
    }   



    //flip in south-west direction
    a = rowNumber + 1;
    b = columnNumber - 1;
    while (a < N && b >= 0) {
        board[a][b] = 1;
        a++;
        b--;
    }



    //flip in south-west direction
    a = rowNumber;
    b = columnNumber - 1;
    while (b >= 0) {
        board[a][b] = 1;
        b--;
    }   



    //flip in north-west direction
    a = rowNumber -1 ;
    b = columnNumber - 1;
    while (a >= 0 && b >= 0) {
        board[a][b] = 1;
        a--;
        b--;
    }



    //flip in north-west direction
    a = rowNumber -1 ;
    b = columnNumber;
    while (a >= 0) {
        board[a][b] = 1;
        a--;
    }


    queenNumber++;
}

int checkGameEnd(int board[N][N], int queenNumber) {
    if (queenNumber == N) {
        return 1;
    }

    for (int i = 0; i < N; i++) {
        int countEqual = 0;
        for (int j = 0; j < N; j++) {
            if (board[i][j] == 1) {
                countEqual++;
            }
        }
        if (countEqual == N) {
            return 1;
        }   
    }
    return 0;
}

int checkResult(int board[N][N]) {
    int checkQueenNumber[N] = {0};
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (board[i][j] == 2) {
                checkQueenNumber[j] = 1;
                break;
            }
        }
    }



    for (int k = 0; k < N; k++) {
        if (checkQueenNumber[k] != 1) {
            return 0;
        }
    }
    return 1;
}

Answer 1

你有一个错字：

    while (a <= N && b < N) {
//           ** <--- here

我使用gcc的address sanitizer找到了它。通常的嫌疑人gdb和valgrind几乎没用。

Asan和其他gcc消毒剂是精彩且被低估的工具，你应该学会使用它们（当然还有gdb和valgrind）。

在C ++程序中中止陷阱6

1 个答案: