C++调用C静态库，出现undefined reference to “” 的问题

哥们在搞一个软件C++写的，跑在linux上，中间涉及到需要调用一个内核中的静态库的步骤。
So here comes the trouble。

---

一开始出现undefined reference to，然而我并不方。这种问题一般都是缺少实现之类的问题。需要添加库，添加头文件路径。添加库路径。So easy！
But！
然而并没有成功，WTF，抓耳挠腮，各种路径查一遍，没错啊，
开始宕机。。。。
But again
感谢蓝灯，感谢google，感谢stackoverflow，

stackoverflow上的答案

But everything works well with other C programs linking this library.
Did you notice that C and C++ compilation create different symbol names on object file level? It’s called ‘name mangling’.
The (C++) linker would show undefined references as demangled symbols in the error message, which might confuse you. If you inspect your test.o file with nm -u you’ll see that the referenced symbol names don’t match with those provided in your library.
If you want to use functions linked in as externals that were compiled using the plain C compiler, you’ll need their function declarations enclosed in an extern “C” {} block which suppresses C++ name mangling for everything declared or defined inside, e.g.:

extern "C" 
{
    #include <dual/xalloc.h>
    #include <dual/xmalloc.h>
}
Even better, you might wrap your function declarations in your header files like this:

#if defined (__cplusplus)
extern "C" {
#endif

/*
 * Put plain C function declarations here ...
 */ 

#if defined (__cplusplus)
}
#endif

在添加头文件的时候需要告诉编译器这个是C的库，然后就完成啦！