同一个内存地址有两个不同的值

2022-01-30 00:00:00 c++

代码

#include <iostream>使用命名空间标准；int main() {常量 int N = 22;int * pN = const_cast(&N);*pN = 33;cout <

`输出`

<块引用>22 0x22ff74
33 0x22ff74
为什么同一个地址会有两个不同的值?
 解决方案 
为什么同一个地址会有两个不同的数据?
没有.允许编译器优化对 const 的任何提及，就好像您在其中编写了它的编译时值.
请注意，如果您执行诸如写入为 const 保留的内存之类的讨厌的技巧，编译器也可以在您运行它时生成擦除硬盘的代码.
Code

#include <iostream>
using namespace std;

int main() {
    const int N = 22;
    int * pN = const_cast<int*>(&N);
    *pN = 33;
    cout << N << '	' << &N << endl;
    cout << *pN << '	' << pN << endl;
}


Output


  22      0x22ff74
  
  33      0x22ff74
Why are there two different values at the same address?
 解决方案 

  Why are there two different datas at the same address?
There aren't. The compiler is allowed to optimize any mention of a const to be as though you had written its compile-time value in there.

Note that the compiler is also allowed to generate code that erases your hard disk when you run it if you do nasty tricks like writing to memory reserved for consts.


	
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