可以C ++编译器假设一个const bool&值不会改变？ [英] Can C++ compiler assume a const bool & value will not change?

问题描述

C ++编译器假设const bool&的值不会改变？

Can the C++ compiler assume a 'const bool &' value will not change?

例如，假设我有一个类：

For example, imagine that I have a class:

class test {
public:
  test(const bool &state)
    : _test(state) {
  }

  void doSomething() {
    if (_test) {
      doMore();
    }
  }
  void doMore();

private:
  const bool &_test;
};

我使用它如下：

void example() {
  bool myState = true;
  test myTest(myState);

  while (someTest()) {
    myTest.doSomething();
    myState = anotherTest();
  }
}

标准允许编译器假设_test的值不会改变。

Is it allowed by the standard for the compiler to assume _test's value will not change.

我认为不是，只是想确定。

I think not, but just want to be certain.

推荐答案

否。因为引用（或指针）是 const 不会阻止其他人使用非< - code> const 参考。像这样：

No. Just because your reference (or pointer) is a const does not stop someone else from having a non-const reference. Like this:

int main(void) {
  bool myState = true;
  test myTest(myState);
  std::cout << myTest.getState() << std::endl;
  myState = false;
  std::cout << myTest.getState() << std::endl;
}

或更简单：

bool a = true;
const bool& b = a;
a = false; // OK
b = true; // error: assignment of read-only reference ‘b’

这篇关于可以C ++编译器假设一个const bool&amp;值不会改变？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！