HP Fortran Programmer's Guide (B3908-90031; September 2011)

Migrating to HP Fortran
Incompatibilities with HP FORTRAN 77
Chapter 10226
• The syntax and functionality of the HP Fortran version of the ON statement is different from the
HP FORTRAN 77 version. For example, ON EXTERNAL and ON INTERNAL are not supported in
HP Fortran. For information about using the ON statement, see the “Using the ON statement” on
page 127.
• HP FORTRAN 77 accepts statement functions that convert arguments; HP Fortran does not.
• HP FORTRAN 77 accepts the { character as comment syntax; HP Fortran does not.
• HP FORTRAN 77 accepts a PROGRAM statement with no name; HP Fortran requires the name.
• HP FORTRAN 77 extends the PROGRAM statement to enable access to command-line arguments;
HP Fortran does not. For information about how to use intrinsics to access command-line arguments,
see “Accessing command-line arguments” on page 174.
• HP FORTRAN 77 supports arrays up to rank 20; HP Fortran supports arrays up to rank 7.
• HP FORTRAN 77 accepts an expression like + -A, but HP Fortran generates a syntax error. Use
+(-A) instead.
• HP FORTRAN 77 does not print leading zeroes in floating-point numbers; HP Fortran does. This
behavior is equivalent to compiling an HP FORTRAN 77 program with the +E4 option (note that this
option is not supported by f90).
• In HP FORTRAN 77, integers that overflow (through initialization or constant folding) are replaced
with the maximum value for that type. If HP Fortran detects integer overflow, it treats it as an error; if it
does not detect it, the overflow value is truncated at runtime.