a**********2
发帖数: 340 | 1 class A
{
int x;
public:
A(int x_):x(x_){}
int& getX(){return x;}
};
A a1(10);
A a2(10);
int& y = a1.getX();
y = a2.getX();
y = 20;
a1和a2中的结果分别是什么？
第一个改变了
第二个没改变
什么原因？ |
l******l
发帖数: 66 | 2 int& y = a1.getX(); this one is reference variable initialization, make y
the reference to a1.x.
y = a2.getX(); is just assignment, make a1.x = a2.x
y = 20; another assignment, make a1.x = 20. |
a**********2
发帖数: 340 | 3 哦，有道理，简单概念没弄清，多谢
【在 l******l 的大作中提到】
: int& y = a1.getX(); this one is reference variable initialization, make y
: the reference to a1.x.
: y = a2.getX(); is just assignment, make a1.x = a2.x
: y = 20; another assignment, make a1.x = 20.
|
r*******y
发帖数: 1081 | 4 I think there would have been compiler error here since it is trying
to change a private member through reference.
But I run this and it is ok.
So we can not change a private member directly but we can
change the private member through reference or pointer.
【在 a**********2 的大作中提到】
: class A
: {
: int x;
: public:
: A(int x_):x(x_){}
: int& getX(){return x;}
: };
: A a1(10);
: A a2(10);
: int& y = a1.getX();
|
m********l
发帖数: 4394 | 5 yea, that's why the stupid '&' was invented.
that's the design of C++, encapsulation is to hide code from OTHER code,
not the programmer.
Same logic applies to 'friend'
【在 r*******y 的大作中提到】
: I think there would have been compiler error here since it is trying
: to change a private member through reference.
: But I run this and it is ok.
: So we can not change a private member directly but we can
: change the private member through reference or pointer.
|
m********l
发帖数: 4394 | 6 你试下这个:
class A
{
int x;
public:
A(int x_):x(x_){}
int& getX(){return x;}
};
A a1(11);
A a2(10);
int& y = a1.getX();
cout << y;
y = a2.getX();
cout << y;
y = 20;
cout << y;
看看结果是啥.
y = a2.getX() 是10吗?
is this the case why reference variable can't be reassigned to a new
reference?
【在 a**********2 的大作中提到】
: 哦，有道理，简单概念没弄清，多谢
|
r*******y
发帖数: 1081 | 7 I like reference. pointer is too complicated
【在 m********l 的大作中提到】
: yea, that's why the stupid '&' was invented.
: that's the design of C++, encapsulation is to hide code from OTHER code,
: not the programmer.
: Same logic applies to 'friend'
|
b*******8
发帖数: 37364 | |
