XL Fortran Enterprise Edition for AIX : User's Guide - IBM

Interlanguage Calls
This section gives details about performing interlanguage calls from your Fortran
program: that is, calling routines that were written in a language other than
Fortran. It assumes that you are familiar with the syntax of all applicable
languages.
Conventions for XL Fortran External Names
To assist you in writing mixed-language programs, XL Fortran follows a consistent
set of rules when translating the name of a global entity into an external name that
the linker can resolve:
v
v
v
v
Both the underscore (_) and the dollar sign ($) are valid characters anywhere in
names.
Because names that begin with an underscore are reserved for the names of
library routines, do not use an underscore as the first character of a Fortran
external name.
To avoid conflicts between Fortran and non-Fortran function names, you can
compile the Fortran program with the -qextname option. This option adds an
underscore to the end of the Fortran names. Then use an underscore as the last
character of any non-Fortran procedures that you want to call from Fortran.
Names can be up to 250 characters long.
Program and symbolic names are interpreted as all lowercase by default. If you
are writing new non-Fortran code, use all-lowercase procedure names to
simplify calling the procedures from Fortran.
You can use the -U option or the @PROCESS MIXED directive if you want the
names to use both uppercase and lowercase:
@process mixed
external C_Func
integer aBc, ABC
common /xYz/ aBc
common /XYZ/ ABC
end
! With MIXED, we can call C_Func, not just c_func.
! With MIXED, these are different variables.
! The same applies to the common block names.
! xYz and XYZ are external names that are
! visible during linking.
Names for module procedures are formed by concatenating __ (two
underscores), the module name, _IMOD_ (for intrinsc modules) or _NMOD_ (for
non-intrinsic modules), and the name of the module procedure. For example,
module procedure MYPROC in module MYMOD has the external name
__mymod_NMOD_myproc.
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