Compiling

So I've downloaded a genetic algorithm package that was written in C, and I'm calling it from some C++ code, so I need to use g++ instead of cc. However it seems that I can't use the same tags in g++ as in cc because if I try to compile using g++ I end up getting a whole bunch of "undefined reference" to the functions defined in the package.
Here is the makefile:

Code:

---

# Generated automatically from Makefile.in by configure.                                                                                                                             
CC          = cc
PRECFLAGS  = -O
CPPFLAGS    = -I/home/bbare/pga/include -Dlinux -DWL=32 -DFORTRANUNDERSCORE -DOPTIMIZE -DFAKE_MPI
FC          = f77
RM          = /bin/rm -f
LDFLAGS    = -s  -L/home/bbare/pga/lib/linux  -lpgaO  -lm
SHELL      = /bin/sh

#    "$@" expands to the target; "$?" expands to the dependency list                                                                                                                 
CFLAGS      = -o $@ $? $(PRECFLAGS)

LINK.c      = @echo "  Compiling $@" ; $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS)

default:
        @make classic
        @make dejong
        @make example
        @make maxbit
        @make maxchar
        @make maxint
        @make name
        @make namefull
        @make udtstr

ga_ee: math_utils.cpp calc_subs.cpp EM.cpp EE_utils.cpp In_out.cpp main.cpp
        $(LINK.c)

classic: classic.c
        $(LINK.c)

dejong: dejong.c
        $(LINK.c)

example: example.c
        $(LINK.c)

maxbit: maxbit.c
        $(LINK.c)

maxchar: maxchar.c
        $(LINK.c)

maxint: maxint.c
        $(LINK.c)

name: name.c
        $(LINK.c)

namefull: namefull.c
        $(LINK.c)

udtstr: udtstr.c
        $(LINK.c)

clean:
        @$(RM) classic dejong example maxbit maxchar maxint name namefull \
              udtstr *.o

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If I put g++ as the compiler (CC variable) it won't even compile the .c files correctly (I get the same undefined reference problems, I've also tried mpiCC (because I think its a parallel program) and I don't know the equivalen c++ compiler, but with mpiCC I still get the undefined references to those functions that I don't get if I just use cc. So I'm quite certain its a flag issue, however I thought that the flags were the same.
Thanks for the help

I forgot to include:
ga_ee is my project, the rest are all examples included with the package I downloaded

This is link time errors not compile time. If an .lib file with headers comes with the package and not source code, you have to pass the lib to g++ to resolve all the external references.

Isn't that what the -L flag does?

> So I've downloaded a genetic algorithm package that was written in C, and I'm calling it from some C++ code
Does it's header file have the
extern "C"
mechanism to tell the C++ compiler that whatever is in the header file should follow C conventions and not C++ conventions?

I'm not sure, what woudl that look like, and how would I add it if it doesn't?

Is the library pgaO.lib or libpgaO.a ?
Are the errors telling you that it cannot find an GNU archive ?

If it's pgaO.lib you may have to change LDFLAGS to

-s -l/home/bbare/pga/lib/linux/pgaO.lib -lm

If even that will work or not. The library may have been built with a different compiler/linker.

The library is libpgaO.a. The errors are all like this:
: undefined reference to `PGACreate(int*, char**, int, int, int)'

and I'm curious as to what Salem was saying. I'm not sure how to check/code what he was talking about

If you look inside most 'C' header files (say stdio.h for example), you should see something like

Code:

---

#ifdef __cplusplus
extern "C" {
#endif
/* bunch of C stuff */
#ifdef __cplusplus
}
#endif

---

If your library header file doesn't have this, then you can do this in your C++ source

Code:

---

extern "C" {
#include <libheaderfile.h>
}

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