Migration of your applications

This section provides information about migrating your applications to IBM® XL Fortran for AIX®, V15.1.3.

The XL Fortran compiler helps you to port or to migrate source code among Fortran compilers by providing full Fortran 90, Fortran 95, Fortran 2003, and partial Fortran 2008 language support, and selected language extensions (including intrinsic functions and data types) from many different compiler vendors. Throughout this document, we refer to these extensions as "industry extensions".

To protect your investment in FORTRAN 77 source code, you can easily invoke the compiler with a set of defaults that provide compatibility with earlier versions of XL Fortran. The f77, fort77, xlf, xlf_r, and xlf_r7 commands provide maximum compatibility with existing FORTRAN 77 programs. The default options provided with the f90, xlf90, xlf90_r, and xlf90_r7 commands give access to the full range of Fortran 90 language features. The default options provided with the f95, xlf95, xlf95_r, and xlf95_r7 commands give access to the full range of Fortran 95 language features. The default options provided with the f2003, xlf2003, and xlf2003_r commands give access to the full range of Fortran 2003 language features. The default options provided with the f2008, xlf2008, and xlf2008_r commands give access to the Fortran 2008 language features supported in this release.

Additionally, you can name your source files with extensions such as .f77, .f90, .f95, .f03, or .f08 and use the generic compiler invocations such as xlf or xlf_r to automatically select language-level appropriate defaults.

To protect your investments in FORTRAN 77 object code, you can link Fortran 90 and Fortran 95 programs with existing FORTRAN 77 object modules and libraries. See Linking new objects with existing ones for details.

More advice is provided in the following sections to help make the transition from an earlier version of the XL Fortran compiler as fast and simple as possible.