The following example illustrates how program units written in different languages can be combined to create a single program. It also demonstrates parameter passing between C/C++ and Fortran subroutines with different data types as arguments.
#include <stdio.h> extern double add(int *, double [], int *, double []); double ar1[4]={1.0, 2.0, 3.0, 4.0}; double ar2[4]={5.0, 6.0, 7.0, 8.0}; main() { int x, y; double z; x = 3; y = 3; z = add(&x, ar1, &y, ar2); /* Call Fortran add routine */ /* Note: Fortran indexes arrays 1..n */ /* C indexes arrays 0..(n-1) */ printf("The sum of %1.0f and %1.0f is %2.0f \n", ar1[x-1], ar2[y-1], z); }
The Fortran subroutine is:
C Fortran function add.f - for C/C++ interlanguage call example C Compile separately, then link to C/C++ program REAL*8 FUNCTION ADD (A, B, C, D) REAL*8 B,D INTEGER*4 A,C DIMENSION B(4), D(4) ADD = B(A) + D(C) RETURN END