Intel XENIX 286 Programmers Guide (86) - Tenox.tc

XENIX Programming cc: C Compiler
Using Object Files and Libraries
The cc command can save useful functions as object files and use these object files to
create programs at a later time. Because obj ect files contain the compiled or
assembled instructions of your source file, they save you the time and trouble of
recompiling the functions each time you need them. All object files created by cc have
the file extension ".o".
The cc command can also use functions found in XENIX system libraries, such as the
standard C library or the screen processing library curses. To use these functions, you
simply supply the name of the library containing them. However, cc accesses the
standard C library automatically and no explicit naming is required.
For convenience, you can create your own libraries with the ar and ranlib commands.
These commands, described in Appendix B, "Programming Commands," copy your useful
object files to a library file and prepare the file for use by the cc command. You can
access the library like any other library in the system if you copy it to the /lib
directory. You must name the library appropriately. The name must begin with a S, M,
L, or H, identifying the model in which the library was compiled. Then, follow the
capital letter with lib and the name you chose. Finally, supply the .a extension. For
example, the small model curses library has the name Slibcurses.a.
Creating Object Files
You can create an object file from a given source file by using the -c (for "compile")
option. This option directs cc to compile the source file without creating a final
program. The option has the form
-c filename ...
where filename is the name of the source file. You may give more than one file name
if you wish. Make sure each name is separated from the next by a space.
To make object files for the source files add.c and mult.c, type
cc -c add.c mult.c
This command compiles each file and calls the compiled source files (object files)
add.o and mult.o. It does not link these files; no executable program is created.
The -c option is typically used to save useful functions for programs to be developed
later. Once a function is in an object file it may be used as is, or saved in a library file
and accessed like other library functions, as described in the following sections.
Note that the cc command automatically creates an object file for each source file in
the command line. Unless the -c option is given, however, it will also attempt to link
these files, even if they do not form a complete program.
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