SUBROUTINE c_sam( c_f , b , s ) BIND(C, NAME='c_sam' )
USE, INTRINSIC :: iso_c_binding , ONLY : c_char , c_int , c_null_char
INTERFACE
  FUNCTION c_f ( x ) RESULT( f_res ) BIND(C)
    USE, INTRINSIC :: iso_c_binding , ONLY : c_int , c_float
    INTEGER ( c_int ) :: f_res
    REAL ( c_float ) :: x
  END FUNCTION c_f
END INTERFACE
! C requires that the string be one character longer than its Fortran
! equivalent as it needs to be null terminated.
CHARACTER(KIND=c_char ) :: s (8)
CHARACTER( len=7) :: t
INTEGER ( c_int ) :: b
INTEGER :: i
   CALL sam( c_f , b , t )
   DO i =1,7
      s ( i )=t ( i : i )
   END DO
   s (8)=c_null_char ! Terminate C string with null character
END SUBROUTINE c_sam

FUNCTION c_f ( x ) RESULT ( f_res ) BIND(C,NAME='c_f ' )
USE, INTRINSIC :: iso_c_binding , ONLY : c_int , c_float
INTEGER ( c_int ) :: f_res
REAL( c_float ) :: x
INTEGER, EXTERNAL :: f
   f_res=f ( x )
END FUNCTION c_f