C++ 结构体和类的区别

Difference between a struct and a class

提问by Siddhartha

Possible Duplicate:
What are the differences between struct and class in C++

可能的重复：
C++ 中的 struct 和 class 之间有什么区别

I've done my homework and had diverse answers on Google. Some say structs do not have inheritance, some say structs do not have access specifiers, while others say they have both.
Could someone clarify then, the differences between a struct and a class in C and C++, and also the difference between a struct in C & C++.

我做完了功课，在谷歌上得到了各种各样的答案。有人说结构没有继承，有人说结构没有访问说明符，而其他人说它们两者都有。
有人可以澄清一下，C 和 C++ 中结构体和类之间的区别，以及 C 和 C++ 中结构体之间的区别。

回答by Keith Thompson

In C++, the only difference between a struct and a class is that struct members are public by default, and class members are private by default.

在 C++ 中，结构体和类之间的唯一区别是结构体成员默认是公共的，而类成员默认是私有的。

However, as a matter of style, it's best to use the structkeyword for something that could reasonably be a struct in C (more or less POD types), and the classkeyword if it uses C++-specific features such as inheritance and member functions.

但是，就风格而言，最好将struct关键字用于可能合理地是 C 中的结构（或多或少 POD 类型）的内容，class如果它使用 C++ 特定的功能（例如继承和成员函数），则最好使用关键字。

C does not have classes.

C 没有类。

C structs cannot use C++-specific features.

C 结构不能使用 C++ 特定的功能。

EDIT:

编辑：

The C++ FAQ Lite, question 7.9, has this to say:

在C ++ FAQ精简版，7.9的问题，有这样一段话：

The members and base classes of a structare publicby default, while in class, they default to private. Note: you should make your base classes explicitlypublic, private, or protected, rather than relying on the defaults.

structand classare otherwise functionally equivalent.

OK, enough of that squeaky clean techno talk. Emotionally, most developers make a strong distinction between a classand a struct. A structsimply feelslike an open pile of bits with very little in the way of encapsulation or functionality. A classfeelslike a living and responsible member of society with intelligent services, a strong encapsulation barrier, and a well defined interface. Since that's the connotation most people already have, you should probably use the structkeyword if you have a class that has very few methods and has publicdata (such things doexist in well designed systems!), but otherwise you should probably use the classkeyword.

成员和的基类struct是public通过默认，而在class，它们默认private。注意：您应该明确地创建基类public, private, 或protected，而不是依赖于默认值。

struct并且class在其他方面在功能上是等效的。

好的，足够干净的技术谈话。在情感上，大多数开发人员在 aclass和 a之间做出了很大的区分struct。一个struct简单的感觉像一个露天堆放位很少在封装或功能的方式。Aclass感觉就像是一个有生命和负责任的社会成员，拥有智能服务、强大的封装屏障和明确定义的接口。由于这是大多数人已经拥有的含义，struct如果您的类只有很少的方法和public数据（这样的东西确实存在于设计良好的系统中！），您可能应该使用class关键字，否则您可能应该使用关键字。

And quoting Stroustrup's "The C++ Programming Language", 4th edition, section 16.2.4:

并引用 Stroustrup 的“The C++ Programming Language”，第 4 版，第 16.2.4 节：

These two definitions of Sare interchangeable, though it is usually wise to stick to one style. Which style you use depends on circumstances and taste. I tend to use structfor classes that I think of as "just simple data structures." If I think of a class as "a proper type with an invariant," I use class. Constructors and access functions can be quite useful even for *struct*s, but as a shorthand rather than guarantors of invariants.

S 的这两个定义是可以互换的，尽管坚持一种风格通常是明智的。您使用哪种风格取决于环境和品味。我倾向于将struct用于我认为“只是简单的数据结构”的类。如果我认为一个类是“具有不变量的适当类型”，我会使用class。构造函数和访问函数甚至对于 * struct*s也非常有用，但作为速记而不是不变量的保证。

回答by Hugh

In C, classes do not exist. In C++, structs have a default access specifier of public, while classes default to private.

在 C 中，类不存在。在 C++ 中，结构的默认访问说明符为public，而类默认为private。

There are several differences between structs in C and C++; in C++ they can inherit from other classes or structs, they can contain member functions, and their names don't need to be referred to with an elaborated type specifier.

C 和 C++ 中的结构体之间存在一些差异；在 C++ 中，它们可以从其他类或结构继承，它们可以包含成员函数，它们的名称不需要用详细的类型说明符引用。