int main() {

    int i = ;

    int j = ;

    int const *p = &i;

    p = &j;

    *p = ;                    //错误，*p的值被const修饰，为只读变量，不可更改

    int * const q = &i;

    *q = ;

    q = &j;                    //错误，q的值被const修饰，为只读变量，不可更改

    return ;

}