c++ - 在构造函数中，我可以获取成员的地址并相信它们将保持不变吗？

Question

我有这行代码:

boneHierarchy = BoneHierarchy(Point3D(24.5f,
                                       84.0f + HumanBoundingBox::HEIGHT/2.0f ,24.5f
                                      ),
                              CompassRadians(0.0f),
                              renderingEngine
                             );

BoneHierarchy 有一些 vector 作为私有(private)成员。我获取 vector 的地址并将它们传递给渲染类。但是当我调用 vector 的 size 成员函数时，我得到了垃圾。我取的是 vector 的地址，而不是其中的元素。

BoneHierarchy::BoneHierarchy(Point3D const& position,
                             CompassRadians const& heading,
                             Renderer* renderingEngine) : counter(0), renderingEngine(renderingEngine)
{    




    CoordinateSystem bodyCoordSys = CoordinateSystem(
                                                     Vector3D(0.0f,1.0f,0.0f),
                                                     Vector3D(0.0f,0.0f,1.0f));


    map<Normal3D::enumeration, TextureCoordinates> cubeTextureKind;
    Normal3D::enumeration normal;
    for (normal = Normal3D::begin(); normal != Normal3D::end(); ++normal)
    {
        cubeTextureKind[normal] = TextureAtlas::textureAtlasCoordLookup(WOOD);
    }
    Bone body = Bone(
                     Vector3D(0.0f, HumanBoundingBox::HEIGHT/2.0f,0.0f),
                     HumanBoundingBox::DIM,
                     Euler3D(0.0f,0.0f,0.0f),
                     cubeTextureKind,
                     bodyCoordSys);
    //TODO there are two positions for the human, one here and one in mesh vbo, unify these into one.
    body.setPosition(Vector3D(position.getX(),position.getY(),position.getZ()));
    body.setEuler(Euler3D((float) (Math::toDegrees(heading.getValue())),0.0f,0.0f));
    drawBone(body,UPDATE_ALL);
    root = body;


    map<string,Renderer::Buffer> vboVariableMap;
    vboVariableMap["aVertexPosition"] = Renderer::Buffer(verticesBuf);
    vboVariableMap["aTextureCoord"] = Renderer::Buffer(texCoordsBuf);
    vboVariableMap["index"] = Renderer::Buffer(indicesBuf);
    cout << "aBoneIndex " << boneIndexBuf.size() << endl;
    vboVariableMap["aBoneIndex"] = Renderer::Buffer(boneIndexBuf);
    vboVariableMap["uBoneMatrix0"] = Renderer::Buffer(transformMatrixBuf);
    GLuint textureID = 0; 
    Renderer::VBODescription vboDescription = Renderer::VBODescription("boneShader",
                                                                       vboVariableMap,
                                                                       GL_DYNAMIC_DRAW,
                                                                       indicesBuf.size(),
                                                                       textureID);
    bufferID = renderingEngine->registerBuffer(vboDescription);
    cout << "bufferID " << bufferID << endl;
    renderingEngine->printBoneIndexSize();
    cout << &(getBoneIndexBuf()) << endl;
}


Renderer::Buffer::Buffer(vector<GLfloat> const& data):
floatData(&data), ushortData(NULL), target(GL_ARRAY_BUFFER)
{
    printf("pointer: %p, size: %lu\n", floatData, floatData->size());
}

Renderer::Buffer::Buffer(vector<GLushort> const& data):
floatData(NULL), ushortData(&data), target(GL_ELEMENT_ARRAY_BUFFER)
{
}

Answer 1

如果接受 Point3D 和 CompassRadians 的 BoneHierarchy 构造函数计算它自己的 vector 成员的地址，那很好。他们的地址不会改变。

该代码还显示了一个赋值语句。右侧临时 BoneHierarchy 的 vector 成员地址将与左侧 boneHierarchy 中存储的 BoneHierarchy 对象的地址不同。确保您没有复制赋值运算符中的地址，否则 boneHierarchy 对象最终将引用不再存在的临时对象的 vector 成员。您还需要检查您的复制构造函数。