c++ - 数组上的 const 值是否与数组上的 const 不同

Question

看来const on array会导致用于存储数组的内存在内存中标记为只读。但为什么 const on int 不会做同样的事情呢？

代码在这里:

int main(int argc, const char * argv[])
{

    const int vv = 10 ;
    int * p = (int *)&vv ;
    *p = 5 ; // work well

    const int aa[3] = {11, 12, 13} ;
    int * pp = (int *)&aa[1] ;
    *pp = 100 ; // EXC_BAD_ACCESS

    return 0;
}

Answer 1

第一个和第二个(如第 7.1.6.1/4 节中所述)都会导致未定义的行为:

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.

事实上，这是 C++ 风格转换(例如 static_cast)的情况之一，const_cast 除外，would have warned you .

在 C 标准中，§6.7.3/5 中也有相同的引用:

If an attempt is made to modify an object defined with a const-qualified type through use of an lvalue with non-const-qualified type, the behavior is undefined.