摘自c++ FAQ Lite:

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.

默认情况下，结构具有公共访问权限，类具有私有访问权限。

就我个人而言，我使用结构作为数据传输对象或作为值对象。当这样使用时，我将所有成员声明为const，以防止其他代码修改。

如果你写的库内部是c++，但API可以被C或c++代码调用，你可以在c++中使用"struct"。你只需要创建一个包含struct和全局API函数的头文件，就可以向C和c++代码公开，如下所示:

// C access Header to a C++ library
#ifdef __cpp
extern "C" {
#endif

// Put your C struct's here
struct foo
{
    ...
};
// NOTE: the typedef is used because C does not automatically generate
// a typedef with the same name as a struct like C++.
typedef struct foo foo;

// Put your C API functions here
void bar(foo *fun);

#ifdef __cpp
}
#endif

然后，您可以使用c++代码在c++文件中编写函数栏()，并使其可从C调用，两个世界可以通过声明的结构共享数据。当然，在混合使用C和c++时还有其他注意事项，但这是一个简化的示例。

正如每个人所说，唯一真正的区别是默认访问。但是，当我不想对简单的数据类进行任何形式的封装时，即使实现了一些helper方法，我也会特别使用struct。例如，当我需要这样的东西时:

struct myvec {
    int x;
    int y;
    int z;

    int length() {return x+y+z;}
};

对于c++来说，结构体和类之间并没有太大的区别。主要的功能区别是，结构的成员在默认情况下是公共的，而在类中默认情况下是私有的。否则，就语言而言，它们是等价的。

也就是说，我倾向于在c++中使用结构体，就像我在c#中做的那样，类似于Brian所说的。struct是简单的数据容器，而类用于对象，除了保存数据外，还需要对数据进行操作。

摘自c++ FAQ Lite:

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.