fpt and WinFPT Reference Manual - Command-line Commands
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OPTIONAL
Syntax:
!% OPTIONAL [:] [:] { <symbol> | <string> }...
Function:
Specifies that the named sub-program argument(s) are optional. fpt uses this information in the argument consistency check (please see CHECK ARGUMENTS). No error or warning is generated if the optional argument is omitted when the routine is called.
Note that in modern Fortran an argument may be declared to be optional. However some extended FORTRAN 77 systems remain in use and do not support the Fortran keyword OPTIONAL. fpt is sometimes used to prepare code for them and optional arguments may be identified by this command.
Names which contain exotic characters such as '%', ':' or '#' (which are all legal on some systems) must be written as quoted strings.
The %OPTIONAL command must be written in code within the scope of declaration of the variables.
Where to Use this Command
| Operating system command line | No |
| Configuration file, config.fsp | No |
| Specification (fsp) files, *.fsp | No |
| Interactively, to FPT> prompt | No |
| Interactive command files | No |
| Embedded in the Fortran code | Yes |
Default
Not optional.
Examples
SUBROUTINE FILE_OPEN(LUN,FNAME,HEADER) INTEGER*4 LUN ! Unit to open CHARACTER*(*) FNAME ! File name CHARACTER*(*) HEADER ! Header at start of file !% OPTIONAL :: HEADER
See Also
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