c++ - 尝试打印值时出现 bad_alloc 异常

Question

我调试了我的 other problem返回到 MyMesh 构造函数。在这段代码中:

if (hollow) {
    numTriangles = n*8;
    triangles=new MyTriangle[numTriangles];
    if (smooth) numSurfacePoints=n*8;
    else numSurfacePoints=n*12;
    surfacePoints=new SurfacePoint[numSurfacePoints];
}else {
    numTriangles = n*4;
    triangles=new MyTriangle[numTriangles];
    if (smooth){
        numSurfacePoints=n*4;
        surfacePoints=new SurfacePoint[numSurfacePoints];
        surfacePoints[n*4]=SurfacePoint(vector3(0,0,1),vector3(0,0,1));
        surfacePoints[n*4+1]=SurfacePoint(vector3(0,0,-1),vector3(0,0,-1));
    }else{
        numSurfacePoints=n*6;
        surfacePoints=new SurfacePoint[numSurfacePoints];
        surfacePoints[n*6]=SurfacePoint(vector3(0,0,1),vector3(0,0,1));
        surfacePoints[n*6+1]=SurfacePoint(vector3(0,0,-1),vector3(0,0,-1));
    }
}

我正在确定网格所需的曲面点和三角形。 bool 值“hollow”和“smooth”表示，如果我需要在锥体上开一个洞，或者法线是否相同，但我认为这无关紧要。

问题是:如果 hollow==false，它会做错事，但不会崩溃，它甚至允许将值放入数组中，但是当我试图像这样计算它时:

for(int i=0;i<numSurfacePoints;i++){
    std::cout<<"vertex "<<i<<"-> pos:"<<surfacePoints[i].pos.x<<" "<<
        surfacePoints[i].pos.y<<" "<<surfacePoints[i].pos.z<<
        " norm:"<<surfacePoints[i].norm.x<<" "<<surfacePoints[i].norm.y<<
        " "<<surfacePoints[i].norm.z<<"\n";
}

当 i=0 时，它会抛出一个 bad_alloc 异常。

此外，有一段时间，上面的代码段向 operator new 抛出一个 bad_alloc，但这个问题自行解决了，但也许它是相关的。

谁能帮帮我？

Answer 1

然后你正在为 N 个表面点分配内存 那么如何为第 N 点和第 N+1 点赋值？

请检查数组边界条件...