C++变量数据被覆盖

Question

我编写C/C++已经有几年了,现在我遇到了一个问题,我似乎无法自己解决.

给定以下结构:

struct InputData
{
    float diameter;
    float length;
    int vertIndex;
    struct InputData *parent;
    vector<InputData*> children;
    bool deadEnd;

    InputData(float dia, float lngth)
    {
        diameter = dia;
        length = lngth;
        vertIndex = NULL;
        parent = NULL;
        deadEnd = false;
    }
};

我首先定义了一些节点及其父/子关系:

InputData i0 = InputData(3.0f, 3.0f);
InputData i1 = InputData(2.0f, 2.0f);
InputData i2 = InputData(1.0f, 1.0f);
InputData i3 = InputData(1.0f, 1.0f);
InputData i4 = InputData(1.0f, 1.0f);
InputData i5 = InputData(1.01f, 0.5f);

i0.children.push_back(&i1);
i1.children.push_back(&i2);
i2.children.push_back(&i3);
i3.children.push_back(&i4);
i4.children.push_back(&i5);

i1.parent = &i0;
i2.parent = &i1;
i3.parent = &i2;
i4.parent = &i3;
i5.parent = &i4;

请注意,i5作为唯一节点没有任何子节点.

然后我继续使用这些数据做一些工作(从main()调用BuildMeshVertices(&i0,&vertices),最后将一个子项添加到i5:

void BuildMeshVertices(InputData* current, vector<SimpleVertex> *vertices)
{
    //Do work

    if(current->children.size() == 1)
    {
        BuildMeshVertices(current->children[0], vertices);
    }
    else if(current->children.size() == 0 && current->deadEnd == false)
    {
        InputData iDeadEnd = InputData(1.01f, 0.5f);
        iDeadEnd.deadEnd = true;
        iDeadEnd.parent = current;
        current->children.push_back(&iDeadEnd);     

        BuildMeshVertices(&iDeadEnd, vertices);
    }
}

一切都很好.i0有一个孩子(i1),i1有一个孩子(i2),依此类推,i5现在也有一个孩子.

我调用了另一个函数(BuildMeshIndices()),突然在这个函数(第63行)中插入几行,新添加的子节点到i5的数据被覆盖.i5仍指向正确的孩子,但这个孩子的数据突然出现乱码.

这是前后的截图(抱歉链接,但我不允许使用IMG标签)

我无法弄清楚为什么会这样,但我觉得这与我糟糕的内存管理有关？

更新此外,它不必这样做.例如,如果将子矢量更改为值向量是首选的C++方式,我更喜欢这样.我试图评论答案,但我不确定你们是否看到了评论(根据常见问题解答,您需要50点声明才能发表评论)？

下面是完整的源代码(一切都没有被删除,但足以重现错误):

#include "stdafx.h"
#include <vector>

using std::vector;

struct InputData
{
    float diameter;
    float length;
    int vertIndex;
    struct InputData *parent;
    vector<InputData*> children;
    bool deadEnd;

    InputData(float dia, float lngth)
    {
        diameter = dia;
        length = lngth;
        vertIndex = NULL;
        parent = NULL;
        deadEnd = false;
    }
};

//--------------------------------------------------------------------------------------
// Vertex types
//--------------------------------------------------------------------------------------
struct SimpleVertex
{
    float Pos;

    SimpleVertex(float Position)
    {
        Pos = Position;
    }
};

void BuildMeshVertices(InputData* current, vector<SimpleVertex> *vertices)
{
    current->vertIndex = vertices->size();

    //Add vertices..

    if(current->children.size() == 1)
    {
        BuildMeshVertices(current->children[0], vertices);
    }
    else if(current->children.size() == 0 && current->deadEnd == false)
    {
        InputData iDeadEnd = InputData(1.01f, 0.5f);
        iDeadEnd.deadEnd = true;
        iDeadEnd.parent = current;
        current->children.push_back(&iDeadEnd);     

        BuildMeshVertices(&iDeadEnd, vertices);
    }
}

void BuildMeshIndices(InputData* current, vector<unsigned long> *indices)
{
    indices->push_back(current->vertIndex+2);
    indices->push_back(current->vertIndex+0);
    indices->push_back(current->vertIndex+1);
    indices->push_back(current->vertIndex+3);
    indices->push_back(current->vertIndex+0);
    indices->push_back(current->vertIndex+2);

    InputData *parent = current->parent;

    unsigned long vOffset;

    if(parent != NULL && parent->children.size() == 1)
    {   
        vOffset = (unsigned long)current->vertIndex;

        indices->push_back(vOffset+7);
        indices->push_back(vOffset+5);
        indices->push_back(vOffset+4);
        indices->push_back(vOffset+6);
        indices->push_back(vOffset+5);
        indices->push_back(vOffset+7);

        indices->push_back(vOffset+10);
        indices->push_back(vOffset+8);
        indices->push_back(vOffset+9);
        indices->push_back(vOffset+11);
        indices->push_back(vOffset+8);
        indices->push_back(vOffset+10);

        indices->push_back(vOffset+15);
        indices->push_back(vOffset+13);
        indices->push_back(vOffset+12);
        indices->push_back(vOffset+14);
        indices->push_back(vOffset+13);
        indices->push_back(vOffset+15);

        indices->push_back(vOffset+18);
        indices->push_back(vOffset+16);
        indices->push_back(vOffset+17);
        indices->push_back(vOffset+19);
        indices->push_back(vOffset+16);
        indices->push_back(vOffset+18);
    }

    if(current->children.size() == 1 && current->deadEnd == false)
    {
        BuildMeshIndices(current->children[0], indices);
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    InputData i0 = InputData(3.0f, 3.0f);
    InputData i1 = InputData(2.0f, 2.0f);
    InputData i2 = InputData(1.0f, 1.0f);
    InputData i3 = InputData(1.0f, 1.0f);
    InputData i4 = InputData(1.0f, 1.0f);
    InputData i5 = InputData(1.01f, 0.5f);

    i0.children.push_back(&i1);
    i1.children.push_back(&i2);
    i2.children.push_back(&i3);
    i3.children.push_back(&i4);
    i4.children.push_back(&i5);

    i1.parent = &i0;
    i2.parent = &i1;
    i3.parent = &i2;
    i4.parent = &i3;
    i5.parent = &i4;

    // Create vertex buffer
    vector<SimpleVertex> vertices;

    BuildMeshVertices(&i0, &vertices);

    // Create index buffer
    vector<unsigned long> indices;

    BuildMeshIndices(&i0, &indices);

    return 0;
}

Answer 1

您正在将指向堆栈对象的指针推入向量中.一旦执行离开范围,堆栈对象将被销毁并且内存将被重用,从而导致伪造值.尝试

InputData *iDeadEnd = new InputData(1.01f, 0.5f);
iDeadEnd->deadEnd = true;
iDeadEnd->parent = current;
current->children.push_back(iDeadEnd);

然后你必须在适当的时候释放内存.