delorie.com/archives/browse.cgi   search  
Mail Archives: djgpp/1999/10/15/09:59:56

Message-ID: <DB85AFBE7C0DD311BF260004ACB80BFCEC57@nex_server.nextransport.com>
From: George Kinney <GKinney AT nextransport DOT com>
To: "'djgpp AT delorie DOT com'" <djgpp AT delorie DOT com>
Subject: RE: extern "C"
Date: Fri, 15 Oct 1999 09:32:38 -0400
MIME-Version: 1.0
X-Mailer: Internet Mail Service (5.5.2448.0)
Reply-To: djgpp AT delorie DOT com

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

------_=_NextPart_001_01BF1711.C1DB13CA
Content-Type: text/plain

>    I have written a C code parser. I have to parse a test code, whose
>files are with .cpp extension, but the code is in C 
Unlikely... .cpp is the most common C++ extension around, and it can
look an awful lot like C to the un-initiated. (Besides, why would anyone 
save C files under C++ extensions? Many compilers, gcc in particular,
use the file extension to determine the language the file is written in.)

>    I'm using gcc to preprocess the input and then parsing the
>preprocessed code. Now the problem is , i have syntax error since, the
>preprocessed code has something like

>extern "C"
>{
This means, compile these functions, and/or data without name mangling
so I can link them to C compiled modules. (or that they are prototypes for 
C compiled funcs, so they won't have mangled names)

In other words, this is a compatibility layer between C and C++.
(Note that extern "C" is specific to the C++ language, so once again, this
is *NOT* a C source file we are talking about here)

>My parser cannot parse the above code. Now i cannot change extension to
>.c since the code uses some header files for which _cplusplus has to be
>defined.

if _cplusplus *has* to be defined for the headers to work, then it is most
certainly
not a C source file. Period.

>Is there any way by which i can prevent this in the preprocessed file?
Why would you? This is a C++ source file, not C.

>If that is not possible, what are different ways in which this may
>appear in preprocessed code?
extern "C" is a compiler directive, not a pre-processing directive, so it
will remain
as you see it after pre-processing.

Get yourself an actual C source file, and try testing it again.

Good luck.

------_=_NextPart_001_01BF1711.C1DB13CA
Content-Type: text/html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">
<META NAME="Generator" CONTENT="MS Exchange Server version 5.5.2448.0">
<TITLE>RE: extern &quot;C&quot;</TITLE>
</HEAD>
<BODY>

<P><FONT SIZE=2 FACE="Arial">&gt;&nbsp;&nbsp;&nbsp; I have written a C code parser. I have to parse a test code, whose</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;files are with .cpp extension, but the code is in C </FONT>
<BR><FONT SIZE=2 FACE="Arial">Unlikely... .cpp is the most common C++ extension around, and it can</FONT>
<BR><FONT SIZE=2 FACE="Arial">look an awful lot like C to the un-initiated. (Besides, why would anyone </FONT>
<BR><FONT SIZE=2 FACE="Arial">save C files under C++ extensions? Many compilers, gcc in particular,</FONT>
<BR><FONT SIZE=2 FACE="Arial">use the file extension to determine the language the file is written in.)</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">&gt;&nbsp;&nbsp;&nbsp; I'm using gcc to preprocess the input and then parsing the</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;preprocessed code. Now the problem is , i have syntax error since, the</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;preprocessed code has something like</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">&gt;extern &quot;C&quot;</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;{</FONT>
<BR><FONT SIZE=2 FACE="Arial">This means, compile these functions, and/or data without name mangling</FONT>
<BR><FONT SIZE=2 FACE="Arial">so I can link them to C compiled modules. (or that they are prototypes for </FONT>
<BR><FONT SIZE=2 FACE="Arial">C compiled funcs, so they won't have mangled names)</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">In other words, this is a compatibility layer between C and C++.</FONT>
<BR><FONT SIZE=2 FACE="Arial">(Note that extern &quot;C&quot; is specific to the C++ language, so once again, this</FONT>
<BR><FONT SIZE=2 FACE="Arial">is *NOT* a C source file we are talking about here)</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">&gt;My parser cannot parse the above code. Now i cannot change extension to</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;.c since the code uses some header files for which _cplusplus has to be</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;defined.</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">if _cplusplus *has* to be defined for the headers to work, then it is most certainly</FONT>
<BR><FONT SIZE=2 FACE="Arial">not a C source file. Period.</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">&gt;Is there any way by which i can prevent this in the preprocessed file?</FONT>
<BR><FONT SIZE=2 FACE="Arial">Why would you? This is a C++ source file, not C.</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">&gt;If that is not possible, what are different ways in which this may</FONT>
<BR><FONT SIZE=2 FACE="Arial">&gt;appear in preprocessed code?</FONT>
<BR><FONT SIZE=2 FACE="Arial">extern &quot;C&quot; is a compiler directive, not a pre-processing directive, so it will remain</FONT>
<BR><FONT SIZE=2 FACE="Arial">as you see it after pre-processing.</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">Get yourself an actual C source file, and try testing it again.</FONT>
</P>

<P><FONT SIZE=2 FACE="Arial">Good luck.</FONT>
</P>

</BODY>
</HTML>
------_=_NextPart_001_01BF1711.C1DB13CA--

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019