HP Fortran Programmer Guide (766160-001, March 2014)

Linking with -b
The -boption is a linker option. It causes the linker to bind PIC object files into a shared library,
instead of creating a normal executable file. The-b option must be used with the ldcommand;
you cannot use thef90 command to create a shared library. Also, the object files specified on
theld command line must consist of PIC; that is, they must have been created with either
+pic=shortor +pic=long.
The following command line links the object filesx.o , y.o, and z.ointo a shared library, named
my_lib.sl:
$ ld -b -o my_lib.sl x.o y.o z.o
Note that thisld command line is much simpler than the ld command line required to link an
executable file (for example, see “Linking with f90 vs. ld” (page 50).
Examples
Example 10 Example 2-6 hi.f90
SUBROUTINE say_hi()
PRINT *, 'Hi!'
END SUBROUTINE say_hi
Example 11 Example 2-7 bye.f90
SUBROUTINE say_bye()
PRINT *, 'Bye!'
END SUBROUTINE say_bye
Example 12 Example 2-8 greet.f90
PROGRAM main
CALL say_hi()
CALL say_bye()
END PROGRAM main
The following command line creates the PIC object files (the -c option suppresses linking):
$ f90 -c +pic=short bye.f90 hi.f90
The next command line links the object files into the shared library:
$ ld -b -o my_lib.sl bye.o hi.o
The last command line compiles the source file greet.f90 and links the object code with the
shared library to produce the executable program a.out:
$ f90 greet.f90 my_lib.sl
The following is the output from a sample run of the executable program:
$ a.out
Hi!
Bye!
Using the C preprocessor
You can use the f90 command to pass source files to the C preprocessor (cpp) before they are
compiled. If the source files contain C preprocessor directives, cpp will act on the directives,
modifying the source text accordingly. The f90 driver will then pass the preprocessed source text
to the compiler. Adding cpp directives to program source files and having the cpp command
preprocess them is a convenient way to maintain multiple versions of a program—for example, a
debugging version and a production version—in one set of files.
60 Compiling and linking