Undefined reference error while linking using g++

[Amit Bhatia]

Hi there.
 I have written a set of classes which I compile and make into a library
libA.a
 Now I am using two more libraries: B,C

So while compiling a test_example.C for the library "A",
 I use the following order while linking

g++ -pg  -O -Wno-deprecated  -ansi -pedantic -o test test.C   -DANSI_HEADERS
-D_G_HAVE_BOOL -I. -I/dir1 -I/dir2   -lA -lB -lC -L. -L/dir1 -L/dir2

But as soon as I do this,  I get a lot of undefined references in one of the
class files which specifically uses library B, complaining about the
function calls that I make in this class to functions of library B.
 Btw, b is written in c and not c++.

./libA.a(co_rr_exp.o)(.text+0xed): In function `A::Co_RR_Exp::Dispose()':
: undefined reference to `qh_restore_qhull(qhT**)'

and many other similar ones.

Any idea why this might be happening?

tia,
amit.