CODEWITHSUNDEEP
c++cbuildmakefile
stressed_geek
stressed_geek

Reputation: 2176

How to build c project mixed with some c++ code using Make?

I have a c project which I have been building using the following Makefile. 

CC=gcc
CFLAGS= -g
LIBS= -lm
MOSEK_H= /home//work/mosek/6/tools/platform/linux32x86/h/
MSKLINKFLAGS= -lmoseknoomp -lpthread -lm
MSKLIBPATH= /home/work/mosek/6/tools/platform/linux32x86/bin/

all: learn

clean: tidy
    rm -f learn

tidy:
    rm -f *.o

learn: spl.o api.o mosek_qp_optimize.o
    $(CC) $(CCFLAGS) spl.o api.o -o learn \
                     $(LIBS) -L $(MSKLIBPATH) $(MSKLINKFLAGS)

spl.o: spl.c
    $(CC) -std=c99 -c $(CFLAGS) spl.c -o spl.o

mosek_qp_optimize.o: mosek_qp_optimize.c
    $(CC) -c $(CFLAGS) mosek_qp_optimize.c -o mosek_qp_optimize.o -I $(MOSEK_H)

api.o: api.c api_types.h
    $(CC) -c $(CFLAGS) api.c -o api.o

The third party c++ code I need to use comprises of .cpp files (graph.cpp, maxflow.cpp, test.cpp) and header files(graph.h, block.h). Independently I can compile the c++ project using the following and it seems to work fine.

g++ test.cpp graph.cpp maxflow.cpp

Now I need to move the code in the main() of test.cpp into api.c of the original c project. Therefore, I need to compile api.c using g++.

I tried the following but it doesn't seem to work:

CC=gcc
CFLAGS= -g
LIBS= -lm
MOSEK_H= /home//work/mosek/6/tools/platform/linux32x86/h/
MSKLINKFLAGS= -lmoseknoomp -lpthread -lm
MSKLIBPATH= /home/work/mosek/6/tools/platform/linux32x86/bin/
MAXFLOW_H= /home/work/maxflow/

all: learn

clean: tidy
    rm -f learn

tidy:
    rm -f *.o

learn: spl.o api.o mosek_qp_optimize.o graph.o maxflow.o
    $(CC) $(CCFLAGS) spl.o api.o mosek_qp_optimize.o graph.o maxflow.o -o learn \
                     $(LIBS) -L $(MSKLIBPATH) $(MSKLINKFLAGS)

spl.o: spl.c
    $(CC) -c $(CFLAGS) spl.c -o spl.o

mosek_qp_optimize.o: mosek_qp_optimize.c
    $(CC) -c $(CFLAGS) mosek_qp_optimize.c -o mosek_qp_optimize.o -I $(MOSEK_H)

api.o: api.cpp api_types.h
    $(CC) -c $(CFLAGS) api.cpp -o api.o -I $(MAXFLOW_H)

graph.o: graph.cpp
    $(CC) -c $(CFLAGS) graph.cpp -o graph.o -I $(MAXFLOW_H) 

maxflow.o: maxflow.cpp
    $(CC) -c $(CFLAGS) maxflow.cpp -o maxflow.o -I $(MAXFLOW_H)

Any ideas, how to go about this?

Upvotes: 0

Views: 306

Answers (1)

Clifford
Clifford

Reputation: 93446

g++ and gcc differ only in what default libraries are linked; g++ will link stdlibc++ as well as libc and libm. Otherwise they are the same compiler; they both support C and C++ compilation. By default any file with a .c extension will be compiled as C code even if g++ is used - it does not gain C++ linkage by virtue of using g++.

Your assertion:

Now I need to move the code in the main() of test.cpp into api.c of the original c project. Therefore, I need to compile api.c using g++.

does not follow; api.c will be compiled by the C compiler, and any C++ code it contains or references to code with C++ linkage will fail. C++ compiled code called from C code must have C linkage. If api.c contains C++ code, you will have to compile it as C++ code (rename it api.cpp or force by compiler switch).

Upvotes: 1

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