Q104672: INFO: Compiler Errors When Compiling a C++ File as a C File

Article: Q104672
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,1.51,1.52,2.0,2.1,4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbCompiler kbCPPonly kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kb
Last Modified: 29-NOV-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft C/C++ for MS-DOS 
- Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52 
- Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0, 5.0, 6.0 
-------------------------------------------------------------------------------

SUMMARY
=======

The following error is typically the first of many returned by the Microsoft
C/C++ Compiler when attempting to compile a file that includes a C++ header file
such as IOSTREAM.H in a C program:

  ios.h(33) : error C2282: 'class' is followed by 'streambuf'. (missing ','?)

In more recent versions of the compiler, the system header files use #ifdef
__cplusplus to prevent the contents from being parsed when compiled as "C"
code.

There may also be multiple C2065, C2297, C2054, C2085, C2143, and C2144 errors,
and eventually a C1003 error indicating that the error count reached 100.

MORE INFORMATION
================

The C/C++ compiler invokes either the C compiler or the C++ compiler according
to the file's extension. If it ends in .C, the C compiler is invoked; if it ends
in .CPP or .CXX, the C++ compiler is invoked.

To invoke the C++ compiler on a file that ends in .C or some other extension, use
the /Tp switch to explicitly specify a C++ source file.

The sample code below produces the errors

  error C2065: 'cout' : undeclared identifier
  error C2297: '<<' : illegal, right operand has type 'char [12]'

if compiled with:

  cl hello.c

The code compiles fine if compiled with:

  cl hello.cpp

  -or-

  cl /Tp hello.c

Sample Code
-----------

  /* Compile options needed:  None
  */ 

  #include <iostream.h>

  void main (void)
  {
       cout << "Hello World";
  }

Additional query words: 8.00 8.00c 9.00 9.10

======================================================================
Keywords          : kbCompiler kbCPPonly kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbVC400 kbAudDeveloper kbZNotKeyword8 kbvc150 kbvc100 kbZNotKeyword3 kbVC500 kbVC600 kbVC151 kbVC200 kbVC210 kbVC32bitSearch kbVC16bitSearch kbVC152 kbVC500Search
Version           : :1.0,1.5,1.51,1.52,2.0,2.1,4.0,5.0,6.0
Issue type        : kbinfo

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.