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From: dik@cwi.nl (Dik T. Winter)
Newsgroups: comp.lang.c,comp.lang.fortran
Subject: Calling C routines from Fortran programs.
Message-ID: <7554@boring.cwi.nl>
Date: 24 May 88 19:55:18 GMT
Organization: CWI, Amsterdam
Lines: 39

I know how to call C routines from Fortran programs on the systems
I work on.  What I want to know is if there are other systems that
require other methods.

The facts. Given a C routine:
	foo(a, n) int *a, n;
that I want to call from a Fortran program as
	K = BAR(A, N)
What should the interface routine (written in C) look like?
The general Unix solution is:
	bar_(a, n) int *a, *n;
	{
		return(foo(a, *n));
	}
Another interface I have encountered is:
	BAR(a, n) int *a, *n;
	{
		return(foo(a, *n));
	}
Reading about the cdecl keyword on the net, I suspect tha Microsoft
interface ought to be:
	cdecl int foo();
	fortran int bar(a, n) int *a, *n;
	{
		return(foo(a, *n));
	}
(but correct me if I am wrong).
And I know one system where I have to write:
	BAR(a, n) int a, n;
	{
		return(foo((int *)(a >> 16), *((int *)(n >> 16))));
	}
because addresses in Fortran and pointers in C are not aligned the same way.

If you know other methods please mail me, I will summarise on the net.
-- 
dik t. winter, cwi, amsterdam, nederland
INTERNET   : dik@cwi.nl
BITNET/EARN: dik@mcvax