I read two sets of data from my example file, targetGrid and InitialGrid (each of which has multiple cells with colours and numbers in them) and output them. Then, I copied the initialGrid to the currentGrid and performed a clockwise rotation operation on the currentGrid in the rotateLeft function and split the Grid into multiple Cells in the rotateGrid for processing. But! I noticed that my currentGrid became 0 when I passed it into the rotateGrid function, and my targetGrid also became 0. Why is this?

Grid Game::rotateGrid(Grid& grid)
{
    int n = static_cast<int>(grid.size());
    Grid rotatedGrid(n, vector<Cell>(n));
    cout << "rotateGrid函数中：" << endl;
    for (int i = 0; i < n; i++)
    { 
        for (int j = 0; j < n; j++)
        {
            int newRow = n - 1 - j;
            int newCol = i;
            if (newRow >= 0 && newRow < n && newCol >= 0 && newCol < n) // 确保新索引在范围内
            {
                rotatedGrid[newRow][newCol] = grid[i][j];
                cout << "Original: " << grid[i][j].number << " " << static_cast<int>(grid[i][j].color) << endl;
                cout << "Rotated: " << rotatedGrid[newRow][newCol].number << " " << static_cast<int>(rotatedGrid[newRow][newCol].color) << endl;
            }
        }
    }
    return rotatedGrid;
}


void Game::rotateLeft(Grid& currentgrid)//逆时针转
{
    cout << "rotateLeft函数中:" << endl;
    printGrid(currentgrid);//能打印
    history.push(currentgrid);//先把当前图像放入栈内，再旋转
    currentgrid=rotateGrid(currentgrid); 
    printGrid(currentgrid);//无法打印
}


void Game::displayAndChoose()
{
    cout << "目标图像:" << endl;
    printGrid(targetGrid);
    cout << endl;
    cout << "当前图像:" << endl;
    printGrid(currentGrid);

    cout << "A. 左转90° "<< " B. 右转90° " << " C. 加热 " << " D. 撤回 "  <<" E.退出游戏 " << endl;
    cout << "你选择：";

    char choice;
    cin >> choice;

    switch (choice)// 根据用户选择调用相应函数  
    {
    case 'A':
    case 'a'://支持小写字母格式
        cout << "displayAndChoose函数中：" << endl;
        printGrid(currentGrid);//能打印
        rotateLeft(currentGrid); 
        printGrid(currentGrid);//无法打印
        break;
    case 'B':
    case 'b':
        rotateRight(currentGrid);
        break;
    case 'C':
    case 'c':
        heat(currentGrid);
        break;
    case 'D':
    case 'd':
        undo(currentGrid);
        break;
    case 'E':
    case 'e':
        cout << "你已退出游戏。" << endl;
        isGameOver = true;
        return;
    default:
        cout << "无效的选择，请重新输入。" << endl;
        break;
    }
    if (compareGrids(currentGrid, targetGrid))
    {
        cout << "恭喜你成功了！" << endl;
        isGameOver = true;
    }
    else
    {
        cout << endl;
        cout << "继续游戏..." << endl;
    }
}

I’ve asked GPT many times, but there’s no way to fix this at all. I tried to make the return value of the rotateGrid function a Grid&, so that the targetGrid doesn’t become 0 after an operation, but I don’t know what the principle is.