2.7 Legacy I/O Considerations

Fortran 95 and legacy Fortran 77 programs are I/O compatible. Executables containing intermixed f77 and f95 compilations can do I/O to the same unit from both the f77 and f95 parts of the program.

However, Fortran 95 provides some additional features:

• ADVANCE=’NO’ enables nonadvancing I/O, as in:

       write(*,’(a)’,ADVANCE=’NO’)  ’Enter size= ’
       read(*,*) n

• NAMELIST input features:

  • f95 allows the group name to be preceded by $ or & on input. The Fortran 95 standard accepts only & and this is what a NAMELIST write outputs.

  • f95 accepts $ as the symbol terminating an input group unless the last data item in the group is CHARACTER, in which case the $ is treated as input data.

  • f95 allows NAMELIST input to start in the first column of a record.

  ENCODE and DECODE are recognized and implemented by f95 just as they were by f77.

See the Fortran User’s Guide for additional information about Fortran 95 I/O extensions and compatibility between f95 and f77.