C++中&的含义是什么？
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What is the meaning of & in c++?
提问by Milad Sobhkhiz
I want to know the meaning of & in the example below:
我想知道下面例子中 & 的含义：
class1 &class1::instance(){
///something to do
}
回答by Lightness Races in Orbit
The &operator has three meanings in C++.
该&运营商在C ++三种含义。
- "Bitwise AND", e.g.
2 & 1 == 3 - "Address-of", e.g.:
int x = 3; int* ptr = &x; - Reference type modifier, e.g.
int x = 3; int& ref = x;
- “按位与”，例如
2 & 1 == 3 - “地址”，例如：
int x = 3; int* ptr = &x; - 引用类型修饰符，例如
int x = 3; int& ref = x;
Here you have a reference type modifier. Your function class1 &class1::instance()is a member function of type class1called instance, that returns a reference-to-class1. You can see this more clearlyif you write class1& class1::instance()(which is equivalent to your compiler).
这里有一个引用类型修饰符。您的函数class1 &class1::instance()是一个class1名为的成员函数instance，它返回一个引用-to- class1。如果您编写（相当于您的编译器），您可以更清楚地看到这一点class1& class1::instance()。
回答by Wim
This means your method returns a referenceto a method1 object. A reference is just like a pointer in that it refers to the object rather than being a copy of it, but the difference with a pointer is that references:
这意味着您的方法返回对 method1 对象的引用。引用就像一个指针，因为它引用对象而不是它的副本，但与指针的区别在于引用：
- can never be undefined / NULL
- you can't do pointer arithmetic with them
- 永远不能是未定义的 / NULL
- 你不能用它们做指针运算
So they are a sort of light, safer version of pointers.
所以它们是一种轻量级、更安全的指针版本。
回答by stefan
Its a reference (not using pointer arithmetic to achieve it) to an object.
它是一个对象的引用（不使用指针算法来实现它）。
回答by Puppy
It returns a reference to an object of the type on which it was defined.
它返回对定义它的类型的对象的引用。
回答by Thomas Jones-Low
In the context of the statement it looks like it would be returning a reference to the class in which is was defined. I suspect in the "Do Stuff" section is a
在语句的上下文中，它看起来将返回对定义的类的引用。我怀疑在“做东西”部分是一个
return *this;
回答by learnerNo1
It means that the variable it is not the variable itself, but a reference to it. Therefore in case of its value change, you will see it straight away if you use a print statement to see it. Have a look on references and pointers to get a more detailed answer, but basecally it means a reference to the variable or object...
这意味着变量不是变量本身，而是对它的引用。因此，如果它的值发生变化，如果您使用打印语句查看它，您将立即看到它。查看引用和指针以获得更详细的答案，但基本上它意味着对变量或对象的引用......
