PROGRAM main_fortran
USE, INTRINSIC :: iso_c_binding , ONLY : c_int , c_float
INTEGER( c_int ) :: i
REAL( c_float ) :: r
COMMON /com/ i , r
INTERFACE
SUBROUTINE init_name
END SUBROUTINE init_name
SUBROUTINE mc ( ) BIND(C,NAME=’mc ’ )
END SUBROUTINE
END INTERFACE
CALL init_name ! load COMMON block in Fortran
CALL mc ! Call C code that gets pointer to COMMON
WRITE(*,’(a,i4,f6.2)’ ) ’ fortran has the block /com/ : ’ , i , r
END PROGRAM main_fortran
SUBROUTINE init_name_c ( comp) BIND(C,NAME=’init_name_c ’ )
USE, INTRINSIC :: iso_c_binding , &
ONLY : c_ptr , c_int , c_float , c_loc
! The C function mc calls init_name_c ( ) to get the
! location of the COMMON block start.
TYPE( c_ptr ) :: comp
INTEGER( c_int ) , TARGET :: i
REAL( c_float ) :: r
COMMON /com/ i , r
! Return a pointer to the first location of the COMMON block.
comp = c_loc ( i )
WRITE(*,’(a,i4,f6.2)’ ) ’ fortran has common block /com/ : ’ , i , r
END SUBROUTINE init_name_c
SUBROUTINE init_name
! This is the original Fortran function
! assigning values to the COMMON BLOCK
INTEGER :: i
REAL :: r
COMMON /com/ i , r
i = 786
r = 3.2
END SUBROUTINE init_name