c++ - const_cast with bool : if condition ignored

Question

VC++ 2010 问题:

const bool bNew = true;
const_cast<bool&>(bNew) = false;
if(bNew)//bNew is false here, but
{
    int i = 0;//this line will be executed
}

为什么？

谢谢。

Answer 1

来自 C++03 标准的第 7.1.5.1/4 节:

Except that any class member declared mutable (7.1.1) can be modified, any attempt to modify a const object during its lifetime (3.8) results in undefined behavior.

您将 bNew 声明为一个 const 对象，然后您通过显式转换它来修改它来破坏类型系统。因此，您调用了未定义的行为，这意味着任何事情都可能发生。