Mail Archives: djgpp/1995/07/20/13:13:50
> I have all the standard libraries for djgpp, at least all the ones I can
> find, but when I try to compile a program it seems that the libraries are
> missing various calls. For instance, I have not been able to find a
> library file containing the ioctl, inp, and outp functions which I
> thought were pretty standard. The library files I have now are C, DBG,
First, not all of the functions you are used to on a PC are ``standard'',
so not all of them must be there (e.g., ioctl() isn't, I think). The DJGPP
FAQ list (available as faq102.zip from the same place you get DJGPP),
section 8.9 explains how to know which functions are in which library.
The correct way of convincing the linker to get all the functions you need
is explained in the FAQ list, sections 8.8 and 8.10:
8.8 Q: When I compile my program, the linker complains about mathematical
functions, although I did #include <math.h>.
Q: The linker complains it cannot find cprintf function.
Q: Why do I get so many unresolved symbols when linking C++ programs?
A: By default, gcc instructs the linker to only look in two libraries:
libgcc.a and libc.a. Some functions aren't included there, so the
linker can't find them. For math functions, like sin() and exp(),
append ``-lm'' to the gcc command line; for pc-specific
functions, like cputs() and cprintf() append ``-lpc''; to use C++
classes append ``-lgpp''. GPL library routines, like obstack and
regex packages are in libgpl.a library; append ``-lgpl'' to use
them.
Note that some C++ classes use math routines, so the -lm should
be given after the -lgplus.
8.10 Q: I give all the libraries to gcc, but I still get unresolved
externals when I link. What gives?
A: Ld is a one-pass linker, it only scans each library once looking
for unresolved externals it saw UNTIL THAT POINT. This means the
relative position of object files and library names on the
command line is significant. You should put all the libraries
AFTER all the object files, and in this order:
-lgpp -lgpl -lm -lpc
If you have any libraries of your own, put them BEFORE the above
system libraries.
If your installation tree is different from the default, i.e., if
you keep the libraries NOT in the default lib/ subdirectory, then
you should add that directory to the line in the [gcc] section of
your DJGPP.ENV file which starts with LIBRARY_PATH, or put into
your environment a variable called LIBRARY_PATH and point it to
the directory where you keep the libraries. Note that if you
invoke the linker by itself (not through the gcc driver), then
DJGPP.ENV must have an [ld] section which sets LIBRARY_PATH, or
else ld.exe won't see that variable in its environment, unless
you put it into the environment yourself (make sure you have
enough available environment space).
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