问题
I was learning about the makefile tool which seems very powerful, and was trying to figure out how to make it work since I have 4 different mains and a common class for 3 of them.
What I'd like to get is:
Linear: g++ -o linear linear.cpp
Linear5: g++ -o linear5 linear5.cpp Contenidor.cpp Contenidor.h
Logarithmic: g++ -o logarithmic logarithmic.cpp Contenidor.cpp Contenidor.h
Constant: g++ -o constant constant.cpp Contenidor.cpp Contenidor.h
With the following Makefile code:
all: linear5 linear logarithmic constant
linear5: linear5.o
g++ -o linear5 linear5.o
linear5.o: linear5.cpp
g++ -cpp linear5.cpp
Contenidor.o: Contenidor.cpp
g++ -cpp Contenidor.cpp
linear: linear.o Contenidor.o
g++ -o linear linear.o Contenidor.o
linear.o: linear.cpp
g++ -cpp linear.cpp
logarithmic: logarithmic.o Contenidor.o
g++ -o logarithmic logarithmic.o Contenidor.o
logarithmic.o: logarithmic.cpp
g++ -cpp logarithmic.cpp
constant: constant.o Contenidor.o
g++ -std=gnu++0x -o constant constant.o Contenidor.o
constant.o: constant.cpp
g++ -cpp constant.cpp
clean:
rm *.o
But an error pops out when I try execute the make command:
g++ -cpp linear5.cpp
g++ -o linear5 linear5.o
g++: linear5.o: No such file or directory
g++: no input files
回答1:
The problem is in the way you perform two-step compilation: you should change every instance of
file.o: file.cpp
g++ -cpp file.cpp
into:
file.o: file.cpp
g++ -c -o file.o file.cpp
This way, you tell g++ to just compile (-c) and not link your file; the output will be an object file, you still have to specify its name with -o though.
Then, the object file can be used in later steps.
来源：https://stackoverflow.com/questions/41066437/c-compiling-multiple-files