g ++合并：ld：致命：文件main.o：未知文件类型

Question

I'm scanning the web and all my project files for solution but still can't find the answer why my linker won't finish the job. Everything smoothly compiles into .o files, but the last make command fails. And here is the Makefile content:

CXX = g++
CXXFLAGS = -Wall -pedantic -c
OBJS = main.o operacje.o porownaj.o 
dzialania: $(OBJS)
    $(CXX) $^ -o $@

main.o: main.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $^ -o $@

operacje.o: operacje.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $^ -o $@

porownaj.o: porownaj.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $^ -o $@

clean:
    rm -f *o

and again, here is the mistake that pops out:

g++ main.o operacje.o porownaj.o -o dzialania
ld: fatal: file main.o: unknown file type
ld: fatal: file processing errors. No output written to dzialania
*** Error code 1
make: Fatal error: Command failed for target `dzialania'

I'm sure it's some kind of a basic mistake but after staring at the file for a few hours I won't notice it anyway. Maybe some of you folks with notice the bug with a fresh eye.

btw. it's my first post after long-term passive lurking, I hope I did everything right. Thanks in advance!

@edit1 OK, I did all the suggested corrections

@edit2 Seems like the problem is caused by improper module division of my program. I'll rearrange it's structure and let you know if it works then. Thanks for all the support!

@edit3 OK, I changed the structure of my program and everything runs smooth, Thanks again!

Answer 1

Try using $< instead of $^ in your rules to compile main.o , operacje.o , and porownaj.o :

main.o: main.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $< -o $@

operacje.o: operacje.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $< -o $@

porownaj.o: porownaj.cpp operacje.h porownaj.h
    $(CXX) $(CXXFLAGS) $< -o $@

That will cause make to compile only the corresponding .cpp file. When you use $^ the header files are passed to the g++ command which tells the compiler to create precompiled headers for them - that's what's ending up in main.o instead of the object file for main.cpp .

Answer 2

GNU make variable definitions like CC = g++ , or CFLAGS = -Wall -pedantic etc.. should each be on its own line:

CC = g++ 
CFLAGS = -Wall -pedantic 
OBJS = main.o operacje.o porownaj.o

BTW, you probably mean

CXX = g++
CXXFLAGS = -Wall -pedantic

You certainly don't want -c explicitly in your CFLAGS or CXXFLAGS ; you really should remove it.

Also, recipes should be after its rule, so you want

dzialania: $(OBJS)  
    $(LINK.cc) $^ -o $@
operacje.o: operacje.cpp operacje.h porownaj.h  
    $(CXX) $(CXXFLAGS) -c $< -o $@

^{The several spaces are actually a single tab character.}

Run make -p to understand the rules known by make ; see also this answer and that one .

Take time to read GNU make documentation .