尝试push_back实例时C ++中向量的奇怪错误

Question

我正在尝试执行push_back但是Code :: Blocks向我发送了一个奇怪的错误。 我已多次调试该代码，但无法确定错误。 方法LoadFromConsole的一行带有错误。

具体来说，当我经过m_blocks.pushback(blocks)会发生错误。 我将粘贴一些课程。 如果您需要更多的类来帮助我，我将粘贴其余代码。 谢谢。

class Block{
    int m_left;
    int m_top;
    int m_right;
    int m_bottom;


public:
Block();

    void set_values(int,int,int,int);

    void loadFromFile(ifstream*f);

      void loadFromConsole(int x,int y, int z, int w);

    int getValue(int side);


    void print();
};



void Block::set_values(int izq,int arriba,int der,int abajo){
    m_top = arriba;
    m_left = izq;
    m_bottom = abajo;
    m_right = der;
}




class Board{
        uint64_t m_timer;
        int m_step;


        int m_width;
        int m_height;


        vector<Block> m_blocks;


        bool solveState(State*state);
        bool isValid(State*state);
        bool isValidSide(State*state,int cell,int side,int cell1,int side1);
        bool isValidSideImplementation(State*state,int cell,int side,int cell1,int side1);


        void printState(State*state);
public:
        Board();


        void loadFromFile(ifstream*file);

        void loadFromConsole(int FIL, int COL);

        void solve();
};
void Board::loadFromConsole(int FIL,int COL ){
        m_height = FIL;
        m_width = COL;
    srand(time(0));

    matriz = new int*[COL];

    for (int i = 0; i < FIL; i++){
        matriz[i] = new int[COL];
    }
    matriz[0][0] = rand()%8+1;
    matriz[0][1] = rand()%8+1;
    matriz[0][2] = rand()%8+1;
    matriz[0][3] = rand()%8+1;

    for (int i = 1; i < m_width; i++){
        matriz[i][0] = rand()%8+1;
        matriz[i][1] =  matriz[i-1][2];
        matriz[i][2] = rand()%8+1;
        matriz[i][3] = rand()%8+1;
    }

    for (int j = 4; j < m_width*4; j+=4){
        matriz[0][j] = matriz[0][j-1];
        matriz[0][j+1] =  rand()%8+1;
        matriz[0][j+2] = rand()%8+1;
        matriz[0][j+3] = rand()%8+1;
    }

    for (int i = 1; i < m_width; i++ ){
        for (int j = 4; j < (m_width*4); j+=4){
            matriz[i][j] = matriz[i][j-1];
            matriz[i][j+1] =  matriz[i-1][j+1];
            matriz[i][j+2] = rand()%8+1;
            matriz[i][j+3] = rand()%8+1;
        }
    }
        for(int i=0;i<m_height;i++){
                for(int j=0;j< (m_width*4);j+=4){
                         Block block;

                         block.print();
                         m_blocks.push_back(block);

                }
        }
}

Answer 1

关于：

matriz = new int*[COL];

for (int i = 0; i < FIL; i++){
    matriz[i] = new int[COL];
}

我认为第一个new是使用FIL而不是COL 。

否则，您将创建一个COL x COL矩阵，而不是FIL x COL COL x COL矩阵，因此很可能因此在进行后续分配时写出矩阵末尾，尤其是当COL小于FIL 。

另外，这段代码肯定超出了矩阵的范围，似乎使用width来引导，而应该使用height ：

for (int i = 1; i < m_width; i++ ){
    for (int j = 4; j < m_width*4; j+=4){
        matriz[i][j] = matriz[i][j-1];

这里不需要乘以四，这会使您读取/写入数组末尾以外的索引，从而调用未定义的行为。 具体来说，如您所说，如果FIL和COL是相同的值，则您访问元素m_width及更大的事实是不正确的。

Answer 2

您的程序行为不确定 。 您正在读取和覆盖您不拥有的内存。 这两个循环计数器远远超出了对所有数据行的基础内存分配的允许索引：

// this is wrong. it will far-exceed the allocated
//  size of matrix[0], which is m_width int vals
for (int j = 4; j < m_width*4; j+=4){
    matriz[0][j] = matriz[0][j-1];
    matriz[0][j+1] =  rand()%8+1;
    matriz[0][j+2] = rand()%8+1;
    matriz[0][j+3] = rand()%8+1;
}

然后...

// Note:this is also wrong. it should be using m_height
for (int i = 1; i < m_width; i++ )
{
    // this is wrong. same problem as the other j-loop 
    for (int j = 4; j < (m_width*4); j+=4){
        matriz[i][j] = matriz[i][j-1];
        matriz[i][j+1] =  matriz[i-1][j+1];
        matriz[i][j+2] = rand()%8+1;
        matriz[i][j+3] = rand()%8+1;
    }
}

在这两个j循环中，您将以4为增量枚举，直到(m_width-1)*4 。 假设COL作为10传入。 枚举为：

4, 8, 12, 16, 20, 24, 28, 32, 36
      ^^^^^^^^^^^^^^^^^^^^^^^^^^   ALL OUTSIDE ALLOCATED RANGE
  ^^^ OUTSIDE ALLOCATED RANGE FOR [j+2] and [j+3]

考虑将每一行分配为：

for (int i = 0; i < FIL; i++)
    matriz[i] = new int[COL]; // << always smaller than 
                              //  4*(COL-1) unless COL is 1