Mixing Fortran and C++

**G'day, folks **:D

Are there examples of Mixed Language programming here? Specifically, I wish to call C++ functions from a Fortran mainline. I've created the following two files, both of which compile without errors under their respective compilers:

Fortran main, test.f:

C program calls C++ 'multiply' which forms the product of two integers, 
C m and n, and returns result in k.
      character ch*1
C
      m=-1
      n=99
      call multiply(m, n, k)
C
      write(*,11) k
11    format(' k = ',i6)
      read(*,21) ch
21    format(a1)
      stop
      end

C++ function, multiply.c:

extern 'C' 
      {
	void __stdcall multiply(int *,int *,int *);
      }
      void __stdcall multiply(int *m, int *n, int *k)
      {
	// Compute the product of m and n, return in k
	int k1;
	int k2;
	k1=*m;
	k2=*n;
	*k=k1*k2;
	return;
      }

Then the following sequence of commands:

FTN95> ftn95 test.f
FTN95> scc multiply.c
FTN95> slink test.obj multiply.obj
WARNING: Missing symbol MULTIPLY.

What am I doing wrong - or not doing?

Eric

You need an interface for multiply in your Fortran code. You can find examples in the standard *.ins files supplied. Details are in FTN95.chm under Mixed Language programming.

Quoted from PaulLaidler You need an interface for multiply in your Fortran code. You can find examples in the standard *.ins files supplied. Details are in FTN95.chm under Mixed Language programming.

Thanks, Paul;

I found 29 .ins files in the /include folder, but the filenames gave no indication of any Mixed Language Programming content. I double-clicked on a .ins file selected at random, but got a warning that my Internet settings were about to change! I hastily backed-out of that one 😃

I explored FTN95.CHM and found a section titled Mixed Language Programming, but it appears to be empty. I did a partial screen-capture, which I've uploaded to my website, at http://www.kurrattan.net/exhibits/FTN95_mixed.jpg

Eric

Try opening win32api.ins in Plato.

You will need something like

STDCALL MULTIPY 'Multiply'(REF,REF,REF)

in your Fortran declarations.

It would be simpler to avoid STDCALL in your C code and to use C_EXTERNAL in your Fortran.

Information in the help file is at

Win32 platform->Mixed language programming->Calling FTN95 from C/C->Calling C/C from FTN95

Quoted from PaulLaidler

Information in the help file is at

Win32 platform->Mixed language programming->Calling FTN95 from C/C->Calling C/C from FTN95

Getting closer 😃

How do I access/invoke the Win32 platform?

Eric

The Win32 platform is what you get by default. The alternative is the .NET platform and you get this by using /CLR on the FTN95 command line.

Quoted from PaulLaidler The Win32 platform is what you get by default.

**G'day, Paul **:)

I'm still not getting it (explanation of Mixed Language Programming). Displayed is:

Setting Environment for FTN95 for Microsoft .NET and Win32

c:\Program Files\Silverfrost\FTN95>ftn95 /help

Invoking 'help' lead me to the same empty page as previously. See http://www.kurrattan.net/exhibits/FTN95.jpg So next I invoked Plato and went in search of 'Mixed Language Programming', but was lead to the same empty page as before.

Does it make a difference that I'm working with files derived from downloading and installing **ftn95_personal.exe **?

Eric

Open the help file as usual (as in your screenshot), then click on Contents (upper left) and check the entries for 'Win32 platform'.

Quoted from Sebastian Open the help file as usual (as in your screenshot), then click on Contents (upper left) and check the entries for 'Win32 platform'.

[size=18:65b5cb69ed]Thankyou excruciatingly, Sebastian![/size:65b5cb69ed] That certainly did the trick 😃 I had everything crossed, waiting for the error messages, but none appeared! Beautiful.

For the benefit of any who may follow in our keystrokes, here is the final state-of-play (any fans of Michael Nyman here?):

Fortran file, test.f:

C program calls C++ 'Multiply' which forms the product of two integers,
C m and n, and returns result in k.
C
      C_EXTERNAL MULTIPLY 'Multiply' (REF,REF,REF):integer*4
C
      character ch*1
C
      m=-2
      n=4008
      call MULTIPLY(m, n, k)
C
      write(*,11) k
11    format(' k = ',i6)
      read(*,21) ch
21    format(a1)
      stop
      end

C++ file, multiply.c:

extern 'C' void  Multiply(int *m, int *n, int *k)
      {
	// Compute the product of m and n, return in k
	int k1;
	int k2;
	k1=*m;
	k2=*n;
	*k=k1*k2;
	return;
      }
 

Then the following sequence of commands:

Note: ... represents a path spec. Screen output not shown.

Thankyou excruciatingly, Sebastian![/size:65b5cb69ed] That certainly did the trick 😃 I had everything crossed, waiting for the error messages, but none appeared! Beautiful.

For the benefit of any who may follow in our keystrokes, here is the final state-of-play (any fans of Michael Nyman here?):

Fortran file, test.f:

C program calls C++ 'Multiply' which forms the product of two integers,
C m and n, and returns result in k.
C
      C_EXTERNAL MULTIPLY 'Multiply' (REF,REF,REF):integer*4
C
      character ch*1
C
      m=-2
      n=4008
      call MULTIPLY(m, n, k)
C
      write(*,11) k
11    format(' k = ',i6)
      read(*,21) ch
21    format(a1)
      stop
      end

C++ file, multiply.c:

extern 'C' void  Multiply(int *m, int *n, int *k)
      {
  // Compute the product of m and n, return in k
  int k1;
  int k2;
  k1=*m;
  k2=*n;
  *k=k1*k2;
  return;
      }
 

Then the following sequence of commands:

Note: ... represents a path spec. Screen output not shown.

[quote:65b5cb69ed] ... \FTN95>ftn95 test.f ... \FTN95>scc multiply.c ... \FTN95>slink test.obj multiply.obj

All of which produced the executable file test.exe, which performed as desired.

**Thankyou to all who have made this possible **:)

Eric

Multiply returns a void rather than an INTEGER*4, i.e. it is a subroutine not a function. As you have found, this does not prevent the code from working.

C_EXTERNAL MULTIPLY 'Multiply' (REF,REF,REF)