为什么这个地址是 0xFFFFFFFF？

Question

In my .h file:

extern std::vector<bool*> selectedContainer;

inline void InitSprite(Sprite* sprite)
{
    bool* selected = new bool(false);
    sprite->onMouseHover = [&](){
        *selected = true;
    };
    sprite->onMouseNotHover = [&](){
        *selected = false;
    };
    selectedContainer.push_back(selected);
}

If for example the onMouseHover of the passed sprite gets called. The selected pointer is always 0xFFFFFFFF.

Answer 1

[&](){

The & means that the lambda captures its object by reference .

bool* selected = new bool(false);

This declares selected in automatic scope. This means that when this function returns selected goes out of scope and gets destroyed. Note that this means that the pointer itself is destroyed, and that has nothing to do, whatsoever, with whatever the pointer is pointing to.

This pointer is captured by reference , so after this function returns any time the lambda referenced the captured object it will end up referencing a destroyed object, hence the undefined behavior.

The simplest solution is to have the lambdas capture objects by value (by default):

[=](){