C++, Fortran Interfacing

On UNIX

• See this Cern Doc
• Fortran runtime libraries need to be included in linking: Ufor for Futil ots
• The order the libraries are given to the linker is important. The first libraries given need to be able to find all their symbols in the libraries given afterwards.

On the Control System

Calling fortran subroutines from c++

In the c++ program:

  #include "forsubs.h"
  int vec_cur[9];
  vxgetn("CSR POS PKUA", 1, 9, vec_cur);

Where forsubs.h contains:

  #include "forstring.h"
  extern "C" {
   int vxgetn(const FORstring &mnem, const int &ele1, const int &ele2,
                   int *vec);
  }

Where forstring.h contains:

  #ifndef FORSTRINGS
  #include <string.h>
  #include <descrip.h>
  class FORstring : private dsc$descriptor_s{
  public:
   FORstring(){
    dsc$b_dtype = DSC$K_DTYPE_T;
    dsc$b_class = DSC$K_CLASS_S;
    dsc$w_length = 0;
    dsc$a_pointer = 0;
   }
   FORstring(char *s){
    dsc$b_dtype = DSC$K_DTYPE_T;
    dsc$b_class = DSC$K_CLASS_S;
    dsc$w_length = strlen(s);
    dsc$a_pointer = s;
   }
   FORstring &operator=(char *s){
    dsc$b_dtype = DSC$K_DTYPE_T;
    dsc$b_class = DSC$K_CLASS_S;
    dsc$w_length = strlen(s);
    dsc$a_pointer = s;
    return *this;
   }
   operator char *(){return dsc$a_pointer;}

   friend void Ctof(FORstring *fstr, char *s[], int numel){
    for(int i=0; i<numel; i++) fstr[i] = s[i];
   }
  };
  #define FORSTRINGS
  #endif