Fortran call from C++

[Dennis Kernighan]

On Microsoft's pages there is an example of making Fortran call from
C++, see http://tinyurl.com/2692f . If I put C code in the test.c and
Fortran code in FORSUBS.FOR and press F5 in C++, I get following
errors:

------- error statement --------

fortrantester error LNK2019: unresolved external symbol "void
__stdcall
PYTHAGORAS(float,float,float *)" (?PYTHAGORAS@@YGXMMPAM@Z) referenced
in
function _main

fortrantester error LNK2019: unresolved external symbol "int __stdcall
FACT(int)" (?FACT@@YGHH@Z) referenced in function _main

fortrantester fatal error LNK1120: 2 unresolved externals

------- error statement --------

So. Is the problem that Fortran compiler is missing? Where could I get
one and how will I tell to C++ that it should use it?

DK

 

[Jeff Schwab]

On Microsoft's pages there is an example of making Fortran call from
C++, see http://tinyurl.com/2692f . If I put C code in the test.c and
Fortran code in FORSUBS.FOR and press F5 in C++, I get following
errors:

------- error statement --------

fortrantester error LNK2019: unresolved external symbol "void
__stdcall
PYTHAGORAS(float,float,float *)" (?PYTHAGORAS@@YGXMMPAM@Z) referenced
in
function _main

fortrantester error LNK2019: unresolved external symbol "int __stdcall
FACT(int)" (?FACT@@YGHH@Z) referenced in function _main

fortrantester fatal error LNK1120: 2 unresolved externals

------- error statement --------

So. Is the problem that Fortran compiler is missing? Where could I get
one and how will I tell to C++ that it should use it?

DK

Wel,, Dennis Kernighan, I don't think the C++ standard attaches any
particular, Fortran-related behavior to the pressing of F5... I think
you need to try one of the MS support groups, or perhaps even read your
linker's documentation.

 

[Charles LaCour]

On Microsoft's pages there is an example of making Fortran call from
C++, see http://tinyurl.com/2692f . If I put C code in the test.c and
Fortran code in FORSUBS.FOR and press F5 in C++, I get following
errors:

Posting some a small executable source file wouldn't hurt.

 

[Gianni Mariani]

On Microsoft's pages there is an example of making Fortran call from
C++, see http://tinyurl.com/2692f . If I put C code in the test.c and
Fortran code in FORSUBS.FOR and press F5 in C++, I get following
errors:

------- error statement --------

fortrantester error LNK2019: unresolved external symbol "void
__stdcall
PYTHAGORAS(float,float,float *)" (?PYTHAGORAS@@YGXMMPAM@Z) referenced
in

The symbol here "?PYTHAGORAS@@YGXMMPAM@Z" is a C++ mangled name. There
is a standard way to tell the C++ compiler to not use "external linkage"
- this is by using the ' extern "C" ' syntax. See below.

function _main

fortrantester error LNK2019: unresolved external symbol "int __stdcall
FACT(int)" (?FACT@@YGHH@Z) referenced in function _main

fortrantester fatal error LNK1120: 2 unresolved externals

------- error statement --------

So. Is the problem that Fortran compiler is missing?

You'll obciously need fortran libraries, but you don't need a fortran
compiler to link with a fortran library.

Where could I get

one and how will I tell to C++ that it should use it?

... I'll let you figure this out ..


The right way to do this using C++ is below:

#include <cstdio>

extern "C"
{
extern int FACT (int n);
extern void PYTHAGORAS (float a, float b, float *c);
};

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