Common blocks and Visual C ++

Deleted_U_Intel · ‎02-09-2001

Ok I've read the Mixed language programming section and tried
porting some legacy code with common blocks and C structures.
No luck. So I tried the examples and still had no luck.

Here is the link error from trying the examples. It looks like your basic name mangling.
What compiler option settings should I look at?

Compiling...
testcommon.cpp
Compiling Fortran...
F: est est1.for
Linking...
testcommon.obj : error LNK2001: unresolved external symbol 'double PI' (?PI@@3NA)
Debug/test1.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

test1.exe - 2 error(s), 0 warning(s)

Here is the test code.

 
test1.for 
  PROGRAM TEST1 
      IMPLICIT NONE 
      INTEGER*4 I 
      INTEGER*4 J 
      REAL*8 PI 
      COMMON/ PI /PI 
      INTERFACE 
         INTEGER*4 FUNCTION TESTCOMMON(N) 
         INTEGER*4 N 
         END FUNCTION TESTCOMMON 
      END INTERFACE 
      PI = DATAN(1.0D0)*4.0D0 
      WRITE(*,*)' PI IN FORTRAN = ',PI 
      J = 5 
      I = TESTCOMMON(J) 
      WRITE(*,*)' I = ',I 
 
      END 
 
testcommon.h 
 
#ifndef TESTCOMMON_H 
#define TESTCOMMON_H 
extern double PI; 
#endif 
 
testcommon.cpp 
 
#include                 // input output streams header file 
#include  
#include  
#include 'testcommon.h'
 
extern 'C'{ int __stdcall TESTCOMMON(int*);}  
int __stdcall TESTCOMMON(int *n){ 
  int result_count = 1; 
  cout << endl; 
  cout << ' n = ' << *n << endl; 
  cout << ' PI = ' << PI <<  endl; 
  return(result_count); 
 
}

Steven_L_Intel1 · ‎02-09-2001

You're almost there. Add 'C' to the extern declaration of PI in your C++ code.

Steve