const int MAX_VAL = 23;
const string NAME = "Micael Jordan";

int n,m;
const int * p = & n;
* p = 5; //编译出错
n = 4; //ok
p = &m; //ok, 常量指针的指向可以变化

const int * p1; int * p2;
p1 = p2; //ok
p2 = p1; //error
p2 = (int * ) p1; //ok,强制类型转换

void MyPrintf( const char * p )
{
    strcpy( p,"this"); //编译出错
    printf("%s",p); //ok
}

int n;
const int & r = n;
r = 5; //error
n = 4; //ok