外部C不能在类级别使用？ [英] extern C can not be used at class level?

问题描述

只是想在Windows环境下确认，VSTS 2008 + C ++项目，我们可以仅适用于外部C运作水平，无法适用于类级别（这样从类用C语言名称重整所有成员函数） ？我曾尝试多种方法，但总是编译错误。

Just want to confirm in Windows environment, VSTS 2008 + C++ project, we could only apply extern C to function level, not be able to apply to class level (so that all member functions from the class use C language name mangling)? I have tried several ways, but always compile error.

在此先感谢，
乔治

thanks in advance, George

推荐答案

您可以排序通过一个非常令人费解的适用的externC成员函数（而是完全法律）黑客：

You can sort of apply extern "C" to a member function via a very convoluted (but entirely legal) hack:

extern "C" typedef int bar_t(int x);

struct foo {
     bar_t bar; // yes, this declares a nonstatic member function!
};

int foo::bar(int x) { return x; } // definition

这根据是可能的ISO C ++ 9.3 03 [class.mfct] / 9：

This is possible according to ISO C++03 9.3[class.mfct]/9:

一个成员函数可以使用函数类型的typedef声明（但不定义）。所得成员函数具有完全相同的类型，因为它会具有如果显式提供说明符的功能，参见8.3.5。

a member function can be declared (but not defined) using a typedef for a function type. The resulting member function has exactly the same type as it would have if the function declarator were provided explicitly, see 8.3.5.

不过，这并没有真正给你买东西，因为ISO C ++ 03 7.5 dcl.link / 4：

However, this doesn't really buy you anything, because of ISO C++03 7.5[dcl.link]/4:

一个C语言联动忽略类成员的名字和成员函数
  类型的类成员函数。

A C language linkage is ignored for the names of class members and the member function type of class member functions.

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