What's the difference between “&” in this program

Question

Below is part of a C++ program:

Circle circle1, &circle2 = circle1, *p = &circle2;

I'm wondering what is the difference in between the two & s there? Thanks so much.

Answer 1

第一（使用& ）的声明一个圆参考，后者是用于获得的存储器地址的地址的操作者circle2 。

Answer 2

Circle circle1, &circle2 = circle1, *p = &circle2;

is equivalent to:

Circle circle1;
Circle &circle2 = circle1;  // & is used to declare a reference variable
Circle *p = &circle2;       // & is used to take the address of circle2

Answer 3

They have two very different meanings. Its easier to see if you split up the terms.

Circle circle1; // A Circle object

Circle& circle2 = circle1; // A Circle reference

Circle* p = &circle2; // A Circle pointer takes the address of a Circle object

In the second line you are declaring a reference to a Circle .

In the third line you are taking the address of a Circle .

So the second line is using & to declare a reference type .

The third line is using & as the address of operator.