I am trying to pass an array from C/C++ into a Fortran 2003 module and get the calculated values back into C/C++. I've been able to pass and return single values (scalars) just fine, but getting an array back and forth is proving difficult. I've found many threads on scalar values and I've been successful at making those work.
I've modeled my array based functions after my working scalar functions.
I am using gcc/gfortran.
Here's the Fortran module (ConvertUnitsLib.f03).
module ConvertUnitsLib
use :: iso_c_binding ! for C/C++ interop
real(c_double), bind(c) :: degF, degC
public DegCtoF
contains
!
! Convert temperature degrees Celsius Fahrenheit
!
real(kind = c_double) function DegCtoF(degC) result(degF) &
& bind(c, name = "DegCtoF")
real(c_double), intent(in), dimension(:) :: degC
real(c_double), dimension(size(degC)) :: degF
do i = 1, size(degC)
degF(i) = ( degC(i) * 1.8 ) + 32
end do
end function DegCtoF
! End of module
end module ConvertUnitsLib
And the C/C++, (CFort.cpp)
#include <stdio.h>
#ifdef __cplusplus
extern"C" {
#endif
double DegCtoF(double *[]);
#ifdef __cplusplus
}
#endif
/**********************************************************************/
int main(int argc, char *argv[])
{
printf("C/C++ and Fortran together!
");
double DegreesC[2] = {32, 64};
double DegreesF[2];
DegreesF = DegCtoF(&DegreesC);
printf("%3.1f [C] = %3.1f [F]
", DegreesC, DegreesF );
return 0;
}
And last but not least, the Makefile
# C++ directives
CC=g++
CFLAGS=-std=c++11
# Fortran directives
FC=gfortran
FFLAGS=-std=f2003
all: clean
$(FC) $(FFLAGS) -c -fcheck=all ConvertUnitsLib.f03
$(CC) $(CFLAGS) -c CFort.cpp
$(FC) $(FFLAGS) ConvertUnitsLib.o CFort.o -o convert
clean:
rm -f *.o
rm -f *.mod
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