What are the differences between struct and class in C++?

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本文探讨了C++中struct与class之间的主要区别。在默认成员访问级别方面，struct默认为public，而class默认为private。此外，当声明继承时，如果未指定访问修饰符，struct将默认为public继承，而class则默认为private继承。

Question：

This question was already asked in the context of C#/.Net.

Now I'd like to learn the differences between a struct and a class in C++. Please discuss the technical differences as well as reasons for choosing one or the other in OO design.

I'll start with an obvious difference:

If you don't specify public: or private:, members of a struct are public by default; members of a class are private by default.

I'm sure there are other differences to be found in the obscure corners of the C++ specification.

Answer：

You forget the tricky 2nd difference between classes and structs.

Quoth the standard (11.2.2):

In absence of an access-specifier for a base class, public is assumed when the derived class is declared struct and private is assumed when the class is declared class.

And just for completeness' sake, the more widely known difference between class and struct is defined in (11.2):

Member of a class defined with the keyword class are private by default. Members of a class defined with the keywords struct or union are public by default.