为什么将“指向非 const 的指针"转换为不合法?指向“指向 const 的指针"

2022-01-23 00:00:00 pointers constants const-correctness c++

将指向非常量的指针转换为指向常数的指针是合法的.

It is legal to convert a pointer-to-non-const to a pointer-to-const.

那么为什么将指向非const的指针转换为指向const的指针是不合法的呢?

Then why isn't it legal to convert a pointer to pointer to non-const to a pointer to pointer to const?

例如，为什么下面的代码是非法的:

E.g., why is the following code illegal:

char *s1 = 0; const char *s2 = s1; // OK... char *a[MAX]; // aka char ** const char **ps = a; // error!

推荐答案

来自标准:

const char c = 'c'; char* pc; const char** pcc = &pc; // not allowed *pcc = &c; *pc = 'C'; // would allow to modify a const object

相关文章