Calling FORTRAN from C

[Oleg Krivosheev]

On Mon, 4 Dec 2000, Robert Boehne wrote:

> To call FORTRAN from C, you should declare the subroutines
> you want to call as extern "C" with their names in uppercase

you spent too much time with C++.

there is no such things as 'extern "C"' in C.

> and underscores prepended to them.  For example to call
> the fortran function INTEGER NINT( INTEGER ) from C you would
> declare it as:
> 
> extern "C" {
> int _NINT( int &arg1 );
> }
> 

at least in Debian 2.2 the prototype would be

int nint_( int* arg );

note the small letters and underscore after the name


> A FORTRAN subroutine is just a function returning void, so it would
> be extern "C" { void _SUB1(sometype &arg1, etc...); }

nope, it would be 

void sub1_( int*, double*, etc... );


> 
> You can also find more details about this in the Fortran FAQ.
> In general though, you should use "nm" on your object files
> to determine the exact names the fortran compiler is giving
> the functions you create.  It should be easy to do this with
> gcc/g77, some compilers make it more difficult, i.e. HP has to have
> a fortran initialization routine called before intrinsic functions
> such as "GETARG" can be used, so YMMV.
> 
> Cheers!
> 
> Robert Boehne

i believe it is offtopic for gcc @gcc.gnu.org, so we'd better move the
discussion to private e-mail

Robert, feel free to ask how to link Fortran and C, there are some
tricks involved in COMMON linkage and string arguments.

OK