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From: jac@muslix.llnl.gov (James Crotinger)
Newsgroups: comp.lang.c++
Subject: Re: How to call C++ functions from Fortran with C++ 2.0
Message-ID: <52273@lll-winken.LLNL.GOV>
Date: 14 Mar 90 20:00:16 GMT
References: <1990Mar13.172657.277@sdr.slb.com>
Sender: usenet@lll-winken.LLNL.GOV
Reply-To: jac@muslix.llnl.gov.UUCP (James Crotinger)
Organization: Lawrence Livermore National Laboratory/UC Davis
Lines: 35


  Another approach would be to make square() and 'extern "C"'
function.  For instance:

  extern "C" void SQUARE(int *i, int*j);

  void SQUARE(int *i, int *j)
  {
    *j = *i * *i;
  }

In fortran this would be called simply as:

  call square(i,j)

BTW, you're example used references for i and j. I would think that
this, too, might be very implementation dependent. I don't believe
that there is any gaurantee in the language that a function which
takes a reference actually work as though it takes a pointer. 

Also, you translated the name to lower case:

  char square__FRiT1 (__0i , __0j ) ==> 
                       char square__frit1_ (__0i , __0j )

If this isn't incorrect, it is at least system dependent as
fortran symbols are supposed to be presented to the linker
in upper case. 

  Of course what there should be is 'extern "FORTRAN"' statement which
would handle not only name demangling, but also would get the case
correct for whatever system you happen to be running on and would
also allow proper use of references.

  Jim