c++ - 结构体和类的区别

Question

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Answer 1

在 C++ 中，结构和类之间的唯一区别是结构成员默认是公共(public)的，而类成员默认是私有(private)的。

但是，作为一种风格，最好将 struct 关键字用于 C 中合理的结构(或多或少的 POD 类型)，和 class 关键字(如果它使用 C++ 特定的功能，例如继承和成员函数)。

C 没有类。

C 结构不能使用 C++ 特定的功能。

编辑:

C++ FAQ Lite ，问题 7.9，有这样的话:

The members and base classes of a struct are public by default, while in class, they default to private. Note: you should make your base classes explicitly public, private, or protected, rather than relying on the defaults.

struct and class are otherwise functionally equivalent.

OK, enough of that squeaky clean techno talk. Emotionally, most developers make a strong distinction between a class and a struct. A struct simply feels like an open pile of bits with very little in the way of encapsulation or functionality. A class feels like 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 struct keyword if you have a class that has very few methods and has public data (such things do exist in well designed systems!), but otherwise you should probably use the class keyword.

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

These two definitions of S are interchangeable, though it is usually wise to stick to one style. Which style you use depends on circumstances and taste. I tend to use struct for 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.