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Combine Fortran program and C++ program into one

I have created a Visual C++ application (SDI). I also have a Fortran application (routines) needed to be combine with the Visual C++ application under Visual Studio environment. Could any one tell me how? Do I need to compile Fortran routines into libraries in advance? How (by using Visual Studio)? How do I call those functions in C++? Thanks.

Richard

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hasmet

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cw43

ASKER

In Fortran, function arguments are actually passed by reference. So even when I call my Fortran subroutines in C++, which function takes variables in Fortran, should I pass pointers instead variables in my cpp file? Also, how to make libraries of Fortran subroutines in Visual Studio on Win95?

Thanks.

hasmet

you need a fortran compiler to create your library, can not use VC++
/* File CMAIN.C */

#include <stdio.h>

extern int __stdcall FACT (int n);
extern void __stdcall PYTHAGORAS (float a, float b, float *c);

main()
{
float c;
printf("Factorial of 7 is: %d\n", FACT(7));
PYTHAGORAS (30, 40, &c);
printf("Hypotenuse if sides 30, 40 is: %f\n", c);
}

C File FORSUBS.FOR "this is your fortran file, use fortran compiler to C create library for this
C
INTEGER*4 FUNCTION Fact (n)
INTEGER*4 n [VALUE]
INTEGER*4 i, amt
amt = 1
DO i = 1, n
amt = amt * i
END DO
Fact = amt
END

SUBROUTINE Pythagoras (a, b, c)
REAL*4 a [VALUE]
REAL*4 b [VALUE]
REAL*4 c [REFERENCE]
c = SQRT (a * a + b * b)
END

as you see, you can specify value or reference

cw43

ASKER

I have compiled my Fortran code into a static libraty by using Digital Visual Fortran compiler, and called it in my C++ code like: extern void __stdcall myfunction(). Of course, I have linked the library in my Visual C++ 5.0 project. However, it does not work. The compiler complained about the unsolved external function. What happened?

hasmet

some fortran compilers are not creating compatible libs (such as watcom)
but digital visual fortran does create compatible one.

two if your fortran code doesnot specifically says [VALUE]
the default is by reference so
extern void __stdcall PYTHAGORAS (float *a, floa t * b, float *c);

but above is for .c files, so if you are doing cpp project (C++ BUT NOT C)
then
extern "C" { void __stdcall PYTHAGORAS (float *a, floa t * b, float *c);}
to say this is C in C++

SO ABOVE ARE THREE problems you may have, other than these
it should run smoothly