fpt: Control of Continuation Lines
In modern Fortran controlling the number of continuation lines permitted in a statement is simply a matter of style. The Fortran 2023 Standard does not specify a maximum number (the total number of characters in a statement is limited to a million and this is unlikely to be a problem!). However, in migration projects it is sometimes necessary to move code backwards and forwards between the original system and the new target, and the number of continuation lines could become an issue.
The permitted number of continuation lines in standard Fortran, and in the legacy systems from which code is likely to be migrated is (or was):
| FORTRAN 77 | 19 |
| Fortran 90 | 49 |
| Fortran 2003 | 255 |
| Fortran 2023 | Unlimited (1,000,000 characters) |
| DEC VMS | Unlimited (13,200 characters) |
| Gould-SEL MPX | Unlimited |
The permitted number of continuation lines occasionally caused a problem in migration to older Fortran standards.
fpt can control the number of continuation lines in the code. It can sub-divide most declaration statements, and will attempt to squeeze executable statements into a user-selected number of lines. The command is, for example:
MAXIMUM NUMBER OF CONTINUATION LINES = 39
An error is reported if the statement cannot be fitted into the required number of lines.
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