c++ - using of extern "C" without function -


I book Dale Rojrson "Inside COM" read a chapter 5, He wrote (sorry, I translated into English Is):

extern "c" is for linkage. So has been marked as a function Exile 'C' , not wil compiler, for example, change the function name to another :? CreateInstance @@ YAPAUIUncnown @@ XZ .

It does not explain the obvious to me but uses the author's extern "C" before the other place because: 

  Include # lt; Objbase.h & gt; Execution 'C' {// {32bb8320-b41b-11cf-a6bb-0080c7b2d682} Execution Constituency IID IID_IX = {0x32bb8320, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0x82, 0x82} near} ; // {32bb8321-b41b-11cf-a6bb-0080c7b2d682} exile constant IID IID_IY = {0x32bb8321, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, has 0x82}}; // {32bb8322-b41b-11cf-a6bb-0080c7b2d682} exile constant IID IID_IZ = {0x32bb8322, 0xb41b, 0x11cf, {0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, has 0x82}}; // Extern C ++ is necessary to allocate memory for constants. }   
 This is not a function ... Why did the author use  extern "C"  in this case?  
 Best regards, Andrey   
 
 
 extern "C" Exile on such a block 'C' is like applying in blocks to make every announcement; It announces the use of C linkage to all of them.  
 Extern "C" on a non-function extern "C" at a function; It uses object cementics for naming, and whatever is relevant.  
 For details, you can refer to the standard, section 7.5 linkage specifications [dcl.link] (although it is written using difficulty using English form).  
 
 It is possible to bring the language linkage to the institutions declared from a different language. In fact, what it means is dependent on a particular language and C ++ implementation, traditionally with C, it means that symbols and calling conventions are changed for the tasks. As far as I remember, there is nothing different for non-functioning in most implementations. It is only that language specification does not say that you can expect those organizations to work with CU unless you do not use extern "C".

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